Period of incubation
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Understanding the Incubation Period of Viral Infections
Incubation Period of Respiratory Viral Infections
The incubation period, the time between exposure to a virus and the onset of symptoms, is a critical factor in managing and controlling infectious diseases. A systematic review of nine respiratory viral infections revealed varying incubation periods. For instance, adenovirus has a median incubation period of 5.76 days, while human coronavirus and severe acute respiratory syndrome coronavirus (SARS-CoV) have median incubation periods of 3.2 days and 4.0 days, respectively. Influenza A and B have shorter incubation periods of 1.4 days and 0.6 days, respectively. Measles has a notably longer incubation period of 12.5 days, whereas parainfluenza, respiratory syncytial virus, and rhinovirus have median incubation periods of 2.6 days, 4.4 days, and 1.9 days, respectively1.
Incubation Period of COVID-19
Estimation from Confirmed Cases
The incubation period of COVID-19, caused by SARS-CoV-2, has been extensively studied due to its global impact. An analysis of 181 confirmed cases outside Hubei province, China, estimated the median incubation period to be 5.1 days, with 97.5% of symptomatic cases developing symptoms within 11.5 days of infection. This supports the current quarantine recommendations of 14 days, although longer monitoring might be necessary in extreme cases2.
Meta-Analyses and Systematic Reviews
Several meta-analyses have provided further insights into the incubation period of COVID-19. One meta-analysis of eight studies found a median incubation period of 5.1 days, with a 95th percentile of 11.7 days, indicating that most cases will develop symptoms within this timeframe3. Another comprehensive meta-analysis of 53 studies reported a global mean incubation period of 6.0 days, with variations observed between regions. For example, the mean incubation period in mainland China was 6.5 days, compared to 4.6 days outside China4. These findings highlight the importance of considering regional differences in incubation periods for effective disease control.
Variability and Influencing Factors
The incubation period of COVID-19 can vary based on several factors, including age and the severity of the disease. A systematic review noted that the mean incubation period ranged from 5.2 to 6.65 days, with the highest 99th percentile reaching up to 20.4 days, suggesting that some cases might have significantly longer incubation periods6. Another study using viral load data estimated a median incubation period of 5.23 days, reinforcing the consistency of these findings across different methodologies9.
Incubation Period of Other Viral Infections
Cholera
The incubation period of cholera, caused by Vibrio cholerae, has been characterized as having a median of 1.4 days. Most cases develop symptoms within 4.4 days of infection, which is crucial for timely clinical and public health interventions7.
Dengue
Dengue viruses have an intrinsic incubation period (IIP) in humans with a mean of 5.9 days, with 95% of cases developing symptoms between 3 and 10 days. This information is vital for clinical diagnosis and outbreak management8.
Viral Gastroenteritis
For viral gastroenteritis, the incubation periods vary among different viruses. Astrovirus has a median incubation period of 4.5 days, norovirus genogroups I and II have a median of 1.2 days, sapovirus has 1.7 days, and rotavirus has 2.0 days. These estimates are essential for improving prevention and control measures in affected settings10.
Conclusion
Understanding the incubation periods of various viral infections is essential for effective disease control and prevention. The incubation period of COVID-19, typically around 5 to 6 days, aligns with quarantine recommendations, although variations exist based on region and other factors. Similarly, knowledge of the incubation periods for other viral infections like cholera, dengue, and viral gastroenteritis aids in clinical and public health decision-making. Accurate and detailed estimates of incubation periods are crucial for managing outbreaks and implementing timely interventions.
Sources and full results
Most relevant research papers on this topic
Incubation periods of acute respiratory viral infections: a systematic review
The median incubation period for acute respiratory viral infections is 5-6 days for adenovirus, 3-2 days for human coronavirus, 4-4 days for severe acute respiratory syndrome coronavirus, 1-5 days for influenza A, 0-6 days for influenza B, 12-5 days for measles, 2
Systematic Review
Highly CitedThe Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application
The median incubation period for COVID-19 is 5.1 days, similar to SARS, supporting current quarantine or active monitoring recommendations for potential exposed individuals.
Meta-Analysis
Rigorous JournalHighly CitedIncubation period of COVID-19: a rapid systematic review and meta-analysis of observational research
The incubation period of COVID-19 is 5.8 days, with uncertainty increasing towards the tail of the distribution, and updating these estimates as new data becomes available is crucial.
Meta-AnalysisRigorous JournalHighly CitedThe incubation period of COVID-19: a global meta-analysis of 53 studies and a Chinese observation study of 11 545 patients
The mean incubation period of COVID-19 is 6.0 days globally but near 7.0 days in the mainland of China, aiding in infection identification and disease control decisions.
Meta-AnalysisRigorous JournalHighly CitedThe incubation period distribution of coronavirus disease 2019 (COVID-19): a systematic review and meta-analysis.
COVID-19 incubation period estimates vary widely, and corrections may be needed before applying them to control and study emerging infectious diseases.
Meta-AnalysisThe incubation period during the pandemic of COVID-19: a systematic review and meta-analysis
The incubation period for COVID-19 is 6.2 days, with potential incubation periods up to 14 days at this stage of the epidemic.
Meta-Analysis
Very Rigorous JournalHighly CitedThe incubation period of cholera: a systematic review.
The median incubation period of cholera is 1.4 days, with 5% developing symptoms within 0.5 days and 95% by 4.4 days after infection.
Systematic ReviewRigorous JournalHighly CitedThe Incubation Periods of Dengue Viruses
Dengue virus incubation periods vary by temperature, with 95% of EIPs between 5 and 33 days at 25°C and 2 and 15 days at 30°C, and no significant differences between serotypes.
Meta-AnalysisHighly CitedEstimation of the incubation period of COVID-19 using viral load data
Using viral load data to estimate the incubation period of COVID-19 may be a useful approach when it is impractical to directly observe the infection event.
Observational StudyIncubation periods of viral gastroenteritis: a systematic review
The median incubation period for viral gastroenteritis is 4.5 days for astrovirus, 1.2 days for norovirus genogroups I and II, 1.7 days for sapovirus, and 2.0 days for rotavirus.
Systematic ReviewRigorous JournalHighly Cited