Is It Still Beneficial to Be Vaccinated if 92% of the Population Is Already Vaccinated?

Check out this answer from Consensus:

It remains highly beneficial to be vaccinated even if 92% of the population is already vaccinated. High vaccination coverage not only enhances herd immunity but also protects vulnerable populations, reduces healthcare costs, and promotes economic growth. Addressing under-vaccination in specific groups is crucial for achieving these benefits. Continued efforts to maintain and improve vaccination rates are essential for safeguarding public health and ensuring equitable access to the benefits of immunization.

With the advent of widespread vaccination programs, many countries have achieved high vaccination coverage rates. However, questions often arise about the necessity and benefits of continuing vaccination efforts when a significant portion of the population is already immunized. This article explores whether it remains beneficial to be vaccinated if 92% of the population is already vaccinated, drawing on recent research findings.

Herd Immunity and Disease Transmission

Herd immunity occurs when a large portion of a community becomes immune to a disease, making its spread unlikely. This concept is crucial in controlling infectious diseases. According to a study on influenza vaccination, even partial vaccination coverage can significantly reduce disease transmission. For instance, vaccinating 20% of children can reduce the total number of influenza cases by 46%, while 80% coverage can reduce cases by 91%1. This demonstrates that higher vaccination rates can drastically lower disease prevalence, benefiting the entire population.

Protecting Vulnerable Populations

Despite high overall vaccination rates, certain groups remain at higher risk for vaccine-preventable diseases. These include preterm infants, pregnant women, individuals with chronic medical conditions, and the elderly. Research indicates that vaccine uptake in these special populations is often lower than desired, even in developed countries2. For example, influenza vaccine coverage among people aged 65 years or older in the US was only 67% during the 2014-2015 season2. Ensuring that these vulnerable groups are vaccinated is crucial for their protection and for maintaining overall public health.

Economic and Health Benefits

Vaccination not only reduces disease incidence but also offers significant economic benefits. Vaccines can lower healthcare costs by preventing diseases that would otherwise require expensive treatments. They also contribute to economic growth by reducing morbidity and mortality, leading to increased life expectancy and productivity3. The annual return on investment in vaccination has been estimated to be between 12% and 18%3. These benefits underscore the importance of maintaining high vaccination rates, even when a large portion of the population is already immunized.

Addressing Under-Vaccination

Despite the high overall vaccination rates, under-vaccination in specific groups remains a challenge. Factors contributing to under-vaccination include fear of adverse outcomes, inconvenience, cost, and lack of awareness2. Improving healthcare providers’ adherence to vaccination recommendations and increasing public awareness can help address these issues. Ensuring that all segments of the population are adequately vaccinated is essential for maximizing the benefits of herd immunity and protecting public health.

 

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Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Aniruddha Belsare has answered Near Certain

An expert from University of Idaho in Epidemiology, Veterinary Science, Ecology

The protection afforded by herd immunity, even at a high rate of vaccination, is not uniform throughout the host population. Furthermore, the risk of disease is underpinned by stochastic processes (population dynamics, individual and group behaviour and beliefs).

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Michaela Hall has answered Near Certain

An expert from UNSW Sydney in Applied Mathematics

To be clear, I am not a vaccinologist or health services expert, so I cannot speak to the risk or severity of MMR vaccine-related side effects. However I can speak from my background in mathematical biology. From a mathematical standpoint, 92% vaccine coverage may not be enough to ensure complete herd protection of unvaccinated individuals from measles in particular. The vaccination coverage required to eliminate measles is estimated to be 90-95% [Nokes and Anderson 1988, Epidemiol Infect], which is consistent with the WHO target of 95% [BMJ 2018;362:k3967]. Even if the UK were able to achieve 95% coverage next year, this unlikely to provide sufficient protection in the near-term, due to poorer coverage among previous cohorts and the necessity to maintain that rate. Additionally, the 90-95% vaccine coverage estimate to eliminate measles is indeed a simplification. The estimate is representative of a closed population where susceptible individuals are scattered evenly throughout. In practice, the population is not closed, many people travel to and from other countries without high MMR vaccine coverage rates and additionally, unvaccinated individuals are often concentrated within local areas or groups, meaning that herd protection may be significantly reduced in some areas.

I have not done, as suggested, a comparison of the risks of side effects from vaccination (e.g. weighted morbidity and mortality) against the risks of contraction of the disease and the likelihood of morbidity and mortality from that. With the recent measles outbreak in the European region [WHO 2018] top of mind, and the rates of travel/migration between the UK and many European nations, I would not consider that 92% vaccine coverage provides adequate herd protection to mitigate the risks of remaining unvaccinated.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Michael J Mina has answered Near Certain

An expert from Harvard University in Vaccines, Immunology, Infectious diseases, Public Health, Epidemiology

Absolutely. Most modern healthcare requires intense focus on the individual. As such most modern healthcare related medicines across a huge range (i.e. tylenol, chemotherapy, insulin, etc) are aimed at protecting and benefitting the individual and, for the most part, the effects of those medicines occur within the person who is taking them.

Vaccines are one of the very few items in modern healthcare where the beneficial effect has consider not only the individual receiving the vaccine, but also the population, and the population level choices. Today, the chances of an individual child contracting measles are exceptionally low – BECAUSE vaccines have been so spectacularly effective at eliminating the disease from entire countries and even continents.

Towards the question at hand, if 92% of the population is vaccinated, those 92% of individuals will be an effective firewall, preventing the infection from spreading and causing disease in the 8% who are not vaccinated. However, if an individual decides that he/she, or their child is protected because of the ‘firewall’ and therefore has such a low chance of getting the infection that they decide not to bother getting the vaccine, then they do not contribute to the firewall, creating a small crack in it. At a population level, it is likely that their decision was either informed by or will inform other people’s decisions to not vaccinate for the same reason. And very quickly, the firewall will contain many cracks because many people think that there is no need.

In the case of measles, measles is so infectious that it only requires a few cracks to start a new measles outbreak. In more concrete numbers, as soon as the population that is vaccinated falls below about 94%, measles will began to come back. We have seen this throughout Europe in 2017 and 2018, where hundreds of thousands of people have been infected with measles, and in the US as well, where small pockets of unvaccinated people led to numerous small cracks in the firewall, and thus an outbreak of measles occurred. Therefore, unlike other modern medicines, vaccines have to be considered within the context of the larger population.

92% is already below what is considered a protective population level to keep herd immunity from breaking down. A further reduction in vaccination rates due to individual decisions to not vaccinate will degrade the firewall for everyone, and measles will return. So yes, even if 92% of the population is vaccinated, it is absolutely beneficial to yourself to get vaccinated, as you help keep the firewall separating yourself and the infections standing up tall.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

James A Roth has answered Likely

An expert from Iowa State University in Immunology, Microbiology, Infectious diseases

Having 92% of the people vaccinated on average should prevent a sustainable outbreak of measles in a population. However, there are pockets of populations with a lower percent of vaccination. A person who is not vaccinated is still susceptible and outbreaks of measles are happening more frequently. All healthy people should be vaccinated so that those who have a weak immune system and don’t adequately respond to the vaccine will have some protection by “herd immunity”.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Cornelis H van Werkhoven has answered Near Certain

An expert from University Medical Center Utrecht in Infectious diseases

It differs per pathogen: the more contageous they are, the higher is the vaccination rate required to prevent outbreaks. Of the MMR vaccine, measles is the most contageous. In a totally susceptible population, one person infected with measles on average infects 20 other persons. The World Health Organisation (WHO) recommends that, in order to prevent spread of measles in the population, over 95% of the population should be vaccinated. So indeed, if the current vaccination rate is 92%, there is an individual benefit of getting the vaccine, because measles will still spread in the population with this vaccination rate.

But even if the vaccination rate would be 95% we have to make sure to keep that rate high. As soon as people start reasoning that their individual risk is very low so they don’t need to be vaccinated, the vaccination rate will rapidly drop. As a result, those not vaccinated will have a risk of getting infected.

Another strong argument (although beyond the question) is that not all people in the population can be vaccinated. In particular patients with severe immunocompromising conditions have a contra-indication. They already have an increased risk of infections and this will further increase if healthy people refuse to be vaccinated.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Anthony DeLegge has answered Near Certain

An expert from Benedictine University in Applied Mathematics

If we are considering a highly contagious (and potentially deadly) disease as the reason for vaccination, then, even with a high proportion of the population being vaccinated, I would still encourage those who can to receive the vaccine anyway for the following reasons:

1: Herd immunity, which is the phenomenon that vaccinating enough of a population would cause the entire population to effectively have immunity from a disease (such as what happened with smallpox), takes time to occur. It’s not like a switch is flipped, and, all of a sudden, everyone has immunity. In the case of smallpox, for example, the first widespread vaccinations were occurring in the early 1800s, but it wasn’t until the 1970s that the disease was considered eradicated.

Thinking that you are protected just because most around you are vaccinated could be a big mistake to make.

2: Immunization from a vaccine isn’t a guarantee. While most people who receive a modern vaccine will develop immunity, this is not always the case, and that immunity could wane over time. This is why we are encouraged, for example, to receive tetanus vaccines every 10 years.

3: People typically don’t stay in an isolated community; they travel to different cities, states, even countries. And, those places may not have as robust of an immunization program. Further, all it takes is one infected individual (who may not even know he/she is sick; measles can have an asymptomatic infectious period for up to two weeks!), and you could end up with the disease yourself.

The biggest thing to consider is that herd immunity is a population-level phenomenon, but it does not mean everyone is automatically protected. It just means that the disease prevalence will continue to decrease, eventually reaching eradication, but people will still get sick.

Vaccination against contagious, potentially deadly diseases, is one of the overall best things most individuals can do for themselves and their health, in my opinion. So, should one vaccinate, even with a high vaccination rate? Absolutely! Keep that vaccination rate high and help lead to the decline, and maybe even eradication, of diseases that were once nuisances to the population!

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Hans-Hermann Thulke has answered Near Certain

An expert from Helmholtz Centre for Environmental Research – UFZ in Epidemiology

The immunisation threshold among people is 95% for MMR according to WHO (so called “herd immunity”). The yet 92% are less and hence cases were rising in numbers. The threshold indicates infections so happening seldom that the average infectee can infect only less than one other, and over time the pathogen is whipped out. However, during that time only the non-vaccinees might become affected. The non-vaccinated individual will have perfect chance to acquire infection once contacting another of the few non-vaccinees. Vaccination would prevent, even if meeting an infectee. Hence, particularly from the individual’s stand point it is beneficial! For the health status of the population, you as the only non-vaccinated individual will have minor importance i.e. the change an individual can cause to the figure of 91.2% vaccinated in 2017-18 in England, is negligible. The fair is that the more people join the non-vaccination group the greater their chance to eventually suffer disease – while the protect people are safe seeing the others suffering.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Pedro Plans-Rubió has answered Near Certain

An expert from Public Health Agency of Catalonia in Public Health, Health Economics

To vaccinate more than 92% of the target vaccination population is still beneficial for two reasons. First, many studies have shown that vaccination benefits outweight its side effects. Second, it is necessary to achieve a vaccination rate higher thah 92% to protect individuals who could not be vaccinated and those with low immunity. Measles viruses are highly contagious because one infected case can generate 12 to 18 secondary cases, spreading the infection in the population. The number of secondary cases could be even higher than 18 in many populations. That means that you need to increase the prevalence of protected individuals to more than the critical prevalence of 91.7% to 94.4% (depending on the measles virus) required to establish suffient herd immunity to block measles transmission in the community. The vaccination coverage necessary to generate the required prevalence of protected individuals to protect all susceptibles is therefore 94.4% to 99.5%, assuming an optimistic value of 95% for measles vaccination effectiveness in preventing secondary cases. With lower valies of effectiveness, the optimal vaccination coverage is higher.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Ivo M Foppa has answered Near Certain

An expert from Battelle Memorial Institute in Epidemiology, Infectious diseases, Biostatistics

I was hesitant to answer, because this is a multilayered and easily misunderstood issue. In an endemic situation (e.g. disease solidly established in a population) vaccination against the cause (e.g. virus) of the given disease, especially in the case of a disease that can lead to death or permanent sequelae (=measles), is a selfish act any rational person would choose: The vaccine is highly effective, with few side effects and not getting vaccinated will result in infection with near certainty. If the situation becomes subendemic (i.e. the disease is not fully established in the population, but is sporadically transmitted), like is the case for measles in the industrialized world, people can choose to avoid vaccination, possibly with a reasonable expectation that their children will not come down with the disease. This is solely due to the fact that the majority still follows the advice to vaccinate which, at this point, has, at least in part, become an altruistic act: Vaccination does still protect the individual, but more importantly it keeps the vaccination coverage at levels preventing the disease from becoming endemic again. So, of course it is beneficial to become vaccinated when vaccination coverage is high (for measles, 92% is actually barely sufficient). But the immediate benefit goes mostly to the society. But only if more and more people become inclined to pass vaccination (and it does not take that many), will vaccination become a “selfish” benefit again. What I said specifically applies to measles. With bacterial diseases (e.g. meningococcal menignitis) it is a different story and I would not feel qualified to answer.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Rafael-J. Villanueva has answered Likely

An expert from Polytechnic University of Valencia in Epidemiology, Computational Mathematics

Mathematical models in epidemiology say that high rates of vaccine coverage protect the non-vaccinated individuals by the herd immunity effect, assuming the vaccine is highly effective. However, the appropriate coverage depends on the disease and other external factors as the weather, social habits, etc.

Therefore, from the Public Health point of view, it is likely that, with a coverage of 92%, no more people need to be vaccinated.

Nevertheless, from the non-vaccinated individual point of view, he/she may want to avoid becoming infected despite the herd immunity may protect him/her.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Anne A Gershon has answered Near Certain

An expert from Columbia University in Medicine

People who are vaccinated have personal protection from a disease which they have been vaccinated against. While herd immunity protects, personal protection is even better. For example if a person has been vaccinated against chickenpox (2 doses) their chances of developing chickenpox are very low. Even if they are exposed to a person with chickenpox or one with herpes zoster (shingles) they are unlikely to be infected with the virus that causes both of these diseases (varicella zoster virus or VZV). If most people around them have been vaccinated and they haven’t been vaccinated they are unlikely to get infected with VZV due to herd immunity. BUT, if they are exposed to someone who happens to have a VZV infection, they are likely to become infected. VZV is highly infectious to others. In addition, the older a person is when they get chickenpox, the more likely they are to become quite ill from it. For example Patsy Mink, member of the US Congress from Hawaii, died of chickenpox at age 74, in 2002. The best way to protect yourself from chickenpox to to take 2 shots of the vaccine. It is very safe and well tolerated in healthy people. The chickenpox vaccine also offers protection against developing herpes zoster. After age 50, however, one should also get further vaccinated against herpes zoster, with the shingles vaccine.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Timothy C Reluga has answered Likely

An expert from Pennsylvania State University in Applied Mathematics, Epidemiology, Infectious diseases, Biology, Economics

Yes, there has been a fair amount of work to understand if there is a break-even point for vaccination coverage in a population. There is a general theory now of where that break point falls, and that theory has been applied to several diseases, including measles, rubella, and smallpox. Today, this theory predicts smallpox is past the breakpoint where we shouldn’t vaccinate against it any more, measles needs ongoing vaccination, while rubella’s breakpoint varies from country to country — some countries should vaccinate against rubella while others shouldn’t.

Now, I’ll give a more detailed answer. I am not a medical doctor, and none of what follows should be interpretted as medical advice.

In public health, we work to maximize the health of our communities. This means trading off the costs of each dose of vaccine against the risks of infection and the costs of infection when it does occur. For vaccines against childhood diseases like measles, there has been testing and trials to help estimate the costs of vaccine. This includes production costs as well as risks and consequences of side-effects. The costs of infection are also well-known for childhood infectious diseases, and are much larger than the costs of their respective vaccines for all historically common diseases. While we have good information about costs, the risk of getting infected is variable and we need to estimate it each time to know if we have reached a tipping point.

The standard example is smallpox. The usual smallpox vaccine has serious side-effects for about 1 in every million people we give it to. So if we vaccinated all of the 300 million people in the US, we’d expect about 300 to get seriously hurt. Smallpox infection itself is a vary dangerous disease, and conservatively, we can say it will seriously hurt 1 in every 20 people it infects. So the cost of vaccine is much lower than the cost of infection. But since 1977, there has not been a wild case of smallpox in the world — smallpox was eradicated thanks in part to the efforts of Rotary international. The risk of being the first new case of smallpox in the world since then is less than 1 in a billion (based on the number of people who have lived in the world since 1977 without getting smallpox). So, smallpox was once a very dangerous disease against which we vaccinated everybody in the world. But today, we don’t vaccinate people against smallpox any more – the smallpox vaccine is more dangerous than smallpox itself — we’ve passed its tipping point. The numbers I’m giving are rough ballparks – we can break them down and refine them if needed but the conclusion should stay the same.

Unfortunately, smallpox is the only human disease we have successfully eradicatd from the world. All other diseases we vaccinated against, including measles, chicken pox, whooping cough, and polio, continue to infect people someplace. So, even when a country has high enough vaccine coverage for herd immunity, there is still a chance somebody will go to another country, get sick, bring the infection back, and expose people. In the US, there can be 100 cases a year of travel related measles. Because of our high level of vaccine coverage, those cases can not spread, so we don’t have to worry about secondary contacts. But that’s still a rough risk of about 1 in 30,000 that a person in the US will be exposed to measles. Measles is not as dangerous as smallpox, but it is still dangerous, killing about 1 in every 500 cases, and blinding about 1 in every 1000 cases. And the vaccine for measles in MMR is very safe — the most dangerous common side-effect is febrile seizure and occurs about once in every 4,000 cases, but while scary, febrile seizures rarely have long-term consequences for a child’s health. Using conservative estimates for the cost of vaccine, the calculations come out close to the tipping point –the cost of vaccine is close to even with the cost of infection. However, measles is highly transmissible, and small decreases in the vaccination rate can result in large increases in infection risk and quickly flip the balance back in favor of vaccination, and there are lots of sources of measles still where that extra infection risk can come from. So we continue to recommend universal vaccination.

Another case where there is an important tipping point is rubella. We have a vaccine against rubella (included in MMR) that has very low costs. Rubella, sometimes called German measles, is usually a very mild viral infection compared to measles or chicken pox, so it is also low cost USUALLY. However, if a woman gets rubella while she’s pregnant, there can be serious complications to the pregnancy. So the expected costs of rubella are small except for adult women and families. This weird effect means there are two reasonable strategies for optimizing public health — either we vaccinate everybody as usual to create herd immunity that projects women who might become pregnant. OR we don’t vaccinate ANYBODY, so the disease spreads as fast as possible, everybody gets rubella as a little kid, and by the time everybody is an adult, women have natural immunity that can project them if they become pregnant. Which strategy is best depends on the country. Countries that have an easy time getting saturating vaccine coverage typically do the first, while countries where vaccination is harder typically do the second. Getting mediocre vaccination coverage levels can make things worse than either of these two strategies because it doesn’t stop spread — just raises that average age of first infection, putting more women at risk.

There are also cases where we do not use vaccines because their costs are too high. For example, we have a vaccine against rabies. Rabies is one of the most dangerous infectious diseases in the world, with nearly a one hundred percent mortality rate. But the vaccine is also very expensive and works best when administered at the site of infection. So, we don’t vaccinate everybody against rabies — only people who have been exposed or are at high risk of being exposed. Anthrax is another case. Anthrax can be very dangerous, but it is very rare, and our vaccine against it hasn’t been very good or particularly safe, so we don’t do mass-vaccination against anthrax.

So, yes, there is a break-point, and there is a theory that takes that break point into account. When new vaccines are developed, we have to study the costs of those vaccines, and weight those costs against the costs of infection to determine who and how to vaccinate.

The numbers given above are all rough and intended for illustrative purposes only. Greater detail about costs can be found in the scientific literature. Some people can expect higher costs than others, particularly if they have weakened immune systems. The risks of infection can vary as well, depending on how much people travel, where they live, how old they are, and many other factors. And risk is very difficult to estimate. If you think about the game “six-degrees of Kevin Bacon”, we realize that our risk of infection depends not just on the people we have direct immediate contact with each day, but also on the a vast extended network friends of friends of friends and each of their risks.

I’ll close by mentioning that there is a second perspective on this question. So far, we’ve been thinking about the break-point for a public health policy. We could also ask what the break-point is for each of us personally. That’s a slightly different question and could lead to a different answer. And people have shown theoretically that vaccination suffers from free-riding effects, where people might choose not to vaccinate because they are already protected by the herd immunity around them. However, most of our vaccines are so safe relative to the costs of infection, and there is so much uncertainty about the risk of infection, that unless there is a particular extenuating circumstance, there is no significant practical benefit to avoiding childhood vaccination.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

James McCaw has answered Near Certain

An expert from University of Melbourne in Epidemiology, Public Health, Applied Mathematics, Biostatistics

For healthy individuals, vaccination is always beneficial. The only people who should not be vaccinated are those with medically-confirmed issues which make vaccination for them unsafe (for example, immunodeficient people). Given the number of people in the population who fall into categories such as this, the benefits of vaccination almost certainly outweigh the risks for those without these medically-confirmed and vaccine-specific issues.

Epidemiologists have developed mathematical models, based on detailed analysis of data and over 50 years of research, which give a precise quantification of how an infectious disease spreads in a vaccinated population. These analyses definitively show that the higher the vaccination coverage, the fewer people get infected. Vaccination helps those vaccinated, and also those unable to be vaccinated (e.g immunocompromised, very young babies).

The trade-off raised in the original question may come into play but only at incredibly high and completely unrealistic vaccination coverage levels, perhaps 99.9% (when 999 out of a 1000 people are vaccinated) or even higher. Such coverage levels are unrealistically high and not studied in detail by epidemiologists. Put another way, 92% is arguably a low (but minimally safe and realistic) level of vaccine coverage, not a high level.

The data analysis techniques mentioned above are also used to study outbreaks of infectious diseases such as measles. Results from these studies are then used to determine if vaccination coverage is sufficiently high to prevent massive outbreaks, helping to guide public policy on targets for minimal vaccination coverage levels.

In summary, with vaccination rates at around 92% it is, without a doubt, highly beneficial for members of the population (without specific medically-confirmed issues) to be vaccinated.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Martin C J Maiden has answered Near Certain

An expert from Oxford University in Vaccines, Epidemiology, Population Biology

The concept of vaccine generated ‘herd immunity’, also called ‘population immunity’ or ‘population protection’, depends on a vaccine generating immunity that not only (i) prevents an immunised individual developing the symptoms of an infectious disease, but also (ii) prevents the vaccinated individual spreading the disease to others. Not all vaccines do this, but most of our most successful vaccines do and this is a major reason why they work so well. Having the disease can also provide this immunity against many pathogens, but is much more risky to the individual.

The degree of population immunisation required to generate herd immunity is dependent on (i) how effective the vaccine is (none are 100% effective, but most work very well in most cases) and (ii) how easily the pathogen in question spread. For example measles spreads really well, with around 20 additional cases arising from each infection, therefore even though the vaccine is very effective (i.e. it works in almost everybody) high levels of vaccination are needed to stop the spread of the disease. This is why measles outbreaks occur when vaccination levels fall.

 The question of whether one should be immunised or not is a balance of benefit to oneself and one’s community against cost of the vaccine and any risks. In simplistic terms, if everyone else has the vaccine, and therefore and bares the cost and risk, the selfishly rational thing for any individual to do is not to be vaccinated oneself and therefore have the benefit of the vaccine indirectly. This of course cannot really work, because if everyone does this then no one gets the vaccine and no one gets the benefit. In practice, as vaccines are much, much safer than the risks of the disease for the great majority of people, and because (i) you can’t eliminate possibility the you might meet someone with the disease or (ii) you might travel to an area where vaccination levels are low, or (iii) vaccination levels may drop in the future, for most people the best choice is to have the vaccine, protecting themselves and those around them.  

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Peter B McIntyre has answered Near Certain

An expert from University of Otago in Infectious diseases

The answer to this question depends on the vaccine/disease in question. For measles, the infectivity is such that even 92% coverage is likely insufficient to maintain elimination of measles in the community and maximum protection requires two doses as up to 10% of people do not develop protective antibodies after one dose but 90% of this remaining 10% will after a second dose. For pathogens like diphtheria coverage of <85% may be sufficient for community protection but does not confer any individual level protection and the only recent death from diphtheria was in a young unimmunised woman who acquired infection from her partially immunised partner when he returned from travel. Similarly other persons unimmunised against diseases like measles are at risk when travelling to areas like Europe and the Philippines where it is currently circulating and infections in adults can be more severe

The article below summarises the herd immunity issue

Frank H Beard, Julie Leask and Peter B McIntyre Med J Aust 2017; 207 (9): . || doi: 10.5694/mja17.00566

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Bridget Haire has answered Near Certain

An expert from UNSW Sydney in Public Health

There is no single tipping point across different vaccine-preventable diseases after which we can assume that ‘herd immunity’ will protect an unvaccinated person – each infectious disease is different (and this depends somewhat on the modes of transmission), and different vaccines also have different levels of efficacy. Circumstances also play a part – it is clearly beneficial to be vaccinated if you are exposed to an infectious disease. As a bioethicist, I argue that one of the benefits of vaccination is moral – being vaccinated contributes to public health above and beyond individual protection, and is thus a social good. This contributes to the herd immunity that the small minority of people for whom a vaccine or vaccines are medically contraindicated rely upon.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Aldo Dekker has answered Likely

An expert from Wageningen University and Research Centre in Epidemiology, Virology, Vaccinology

Most of or work was focussing on transmission of foot-and-mouth disease, but some general principles will apply to other diseases. The reproduction ratio (R-naught) is defined as the number of new infections caused by a typically infectious individual in a fully susceptible population. If the R-naught is below 1 an infection will (eventually) die out. By vaccination we reduce the number of susceptible individuals. The fraction of individuals that have to be protected against infection (f) should be larger than 1-1/R-naught. In the case of 92% protected individuals infectious agents with a R-naught up to 12.5 would die out.

But 92% vaccination coverage does not mean 92% of individuals protected. In FMD vaccine the international standard is at least 70% protection against virulent challenge after one shot of vaccine (OIE manual, OIE=world organisation for animal health). Most likely many vaccines sold world-wide do not fulfil the OIE standards, but in human medicine that is probably better controlled. Nevertheless, protection against infection is most likely lower than the vaccination coverage.

We have performed many studies quantifying the R-naught of foot-and-mouth disease in groups of animals in small stables. Although the estimates for R-naught in endemic countries are low (mostly between 1.2 and 1.5), the estimates of R-naught in our animal studies are mostly way above 10. The contract structure when individuals have to share a small space is different then when individuals are kept with sufficient distance. So this clearly shows that the R-naught estimate can be different in different situations. So when you are in a meeting with individuals that do not want to be vaccinated, first of all the vaccination coverage in that population is much lower than 92%, and the R-naught in some situations can be higher. So it is clear if you want to protect yourself and the people you love that are close to you, you better get your shots.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Luis Acedo has answered Near Certain

An expert from Technical University of Valencia in Epidemiology

The risk of side-effects by vaccination is surely smaller than the risk of being infected by a tourist or immigrant. In Spain 95% of the population is vaccinated with MMR but there have been some resurgence of rubella and a fatal case of difteria as a consequence of the anti-vaccine campaigners combined with immigration of unvaccinated individuals.

So, although mathematical models show that herd immunity is almost perfect for coverages higher of 90% in most infectious diseases that affect exclusively human hosts, in cases of diseases with severe morbidity and possible mortality it would be dangerous and negligent to declare that above a certain point of vaccination coverage we can be sure that vaccination is not necessary (or even counterproductive by the likelihood of side-effects).

The fact that the world is increasingly connected, and we can not ignore population mobility, makes that high vaccination coverages in our country are not a guarantee of herd immunity protection.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Alberto Giubilini has answered Near Certain

An expert from Oxford University in Bioethics

92% is not enough for herd immunity from measles. And even if there is herd immunity, vaccination is still beneficial at the individual level as vaccination coverage in a community might change suddenly and/or a child might travel to places where there is no herd immunity.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Seth Blumberg has answered Near Certain

An expert from New York University in Epidemiology, Internal Medicine, Applied Mathematics

There are several important reasons to get vaccinated, even if population immunity is high:

• Measles is extremely transmissible (Basic Reproduction number may be above 15) and so the 92% vaccne coverage may not be sufficient for individual protection
• Vaccine coverage is not uniform and pockets of susceptibility can put certain people at greater risk than others
• MMR vacccine is extremely safe. Prior concerns regarding a link to autism were based on fraudalent data
• Those who are vaccinated help protect the rest of the community, including those who have medical conditions that are contra-indicatons to vaccination
• It is important for each individual to demonstrate the importance of vaccination so that vaccine coverage remains high. If folks don’t get vaccinations due to a perception of minimal ‘individual benefit’ (akin to the prisoner’s dilemma) then we will all lose.

 

Is it still beneficial to be vaccinated if 92% of the population is already vaccinated?

Kristine K Macartney has answered Near Certain

An expert from University of Sydney in Infectious diseases, Vaccines

The answer to this question depends on which vaccine used/disease/s prevented, but assuming MMR vaccine there is still strong individual benefit.

Measles virus continues to circulate around the world, with increase in cases globally in last few years. Similar mumps and rubella virus remain in circulation in most countries. Thus, unless a child/person is completely and permanently isolated, they will have a chance of being infected with these viruses through contact with others no matter where they live. Adverse effects from MMR are generally mild, whereas adverse effects from measles are not uncommon and can be devastating. Similarly, mumps and rubella can have serious adverse effects.