Flu a vs flu b symptoms
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Comparing Symptoms of Influenza A and Influenza B
Introduction to Influenza A and B
Influenza A and B are the two main types of influenza viruses that cause seasonal flu epidemics in humans. While both types can lead to similar respiratory illnesses, there are notable differences in their clinical presentations, severity, and outcomes.
Age and Demographics
Age Distribution
Influenza A tends to affect younger populations more frequently than Influenza B. Studies have shown that the median age of patients with Influenza A is significantly lower compared to those with Influenza B. For instance, one study found the median age for Influenza A patients to be 2.0 years, whereas for Influenza B, it was 3.9 years1. Another study reported that Influenza A patients were younger with a median age of 67.5 years compared to 77 years for Influenza B patients2.
Underlying Conditions
Patients with Influenza B are more likely to have underlying chronic conditions such as chronic kidney disease compared to those with Influenza A2. Additionally, Influenza B patients are more likely to have a vaccine-indicated condition1.
Symptomatology
Common Symptoms
Both Influenza A and B share many overlapping symptoms, making clinical differentiation challenging without laboratory testing. Common symptoms include fever, cough, and sore throat. However, there are some differences in the prevalence of specific symptoms between the two types.
Distinct Symptoms
- Influenza A: Patients with Influenza A are more likely to present with higher body temperatures, higher leukocyte counts, and elevated C-reactive protein (CRP) levels. They also experience dyspnea more frequently2.
- Influenza B: Symptoms more commonly associated with Influenza B include headache, abdominal pain, myalgia, and vomiting1 2. Additionally, runny nose and rhinorrhea are more frequent in Influenza B cases compared to Influenza A4.
Severity and Outcomes
Hospitalization and ICU Admission
Influenza A is generally associated with more severe disease outcomes. Patients with Influenza A are more likely to be admitted to the hospital for longer durations and have higher in-hospital mortality rates compared to those with Influenza B2. However, among pediatric patients, Influenza B has been associated with a higher risk of ICU admission, particularly in children aged 10 years and older1.
Mortality Rates
The mortality rate for Influenza B in pediatric cases is higher compared to Influenza A. One study reported that the proportion of deaths attributable to Influenza B was significantly greater than that for Influenza A, with an adjusted odds ratio of 2.65 for influenza-related mortality1. In contrast, another study found that the in-hospital mortality rate was higher for Influenza A patients compared to Influenza B during the 2017/2018 season2.
Conclusion
While Influenza A and B share many clinical features, there are distinct differences in their symptomatology, severity, and outcomes. Influenza A tends to affect younger populations and presents with more severe symptoms and higher mortality rates in adults. On the other hand, Influenza B is more likely to cause specific symptoms such as headache, abdominal pain, and myalgia, and has a higher mortality rate in pediatric cases. Accurate diagnosis through laboratory testing is essential for appropriate management and treatment of both types of influenza.
Sources and full results
Most relevant research papers on this topic
Hospitalization for Influenza A Versus B
Pediatric influenza B infection has higher mortality rates than influenza A, and children aged 10 years and older have a significant risk of ICU admission.
Observational Study
Highly CitedIs there a clinical difference between influenza A and B virus infections in hospitalized patients?
Influenza A patients had more severe symptoms and younger age, but symptoms were overlapping, necessitating point-of-care testing for accurate diagnosis.
Observational Study
Rigorous JournalCharacteristics of hospitalized adult patients with laboratory documented Influenza A, B and Respiratory Syncytial Virus – A single center retrospective observational study
FluA and FluB both contribute equally to hospitalizations, but RSV has a greater impact on older, sicker patients and worse outcomes, while vaccination appears to protect against FluB hospitalizations.
Observational StudyRigorous JournalComparison of influenza type A and B with COVID‐19: A global systematic review and meta‐analysis on clinical, laboratory and radiographic findings
COVID-19 and influenza have many differences in clinical manifestations and radiographic findings, making timely detection and distinction crucial for effective treatment.
Meta-AnalysisRigorous JournalHighly CitedCo-circulation of Influenza A and B During the 2016–2017 Influenza Season at Rush University Medical Center
Influenza A (H3N2) does not appear to disproportionally affect those with most medical comorbidities and is not disproportionately associated with clinical complications compared to influenza B (B/Yamagata).
Observational StudyClinical Characteristics Are Similar across Type A and B Influenza Virus Infections
Despite differences in age distribution, the clinical illness produced by different influenza virus types and subtypes is indistinguishable among patients consulted by general practitioners for acute respiratory infections.
Observational StudyRigorous JournalHighly CitedSeverity and outcomes of influenza-related pneumonia in type A and B strains in China, 2013–2019
FluA-related pneumonia patients experience more severe clinical outcomes and increased risk of invasive ventilation, intensive care unit admission, and 30-day mortality compared to FluB-related pneumonia patients.
Observational StudyRigorous JournalXofluza (Baloxavir Marboxil) for the Treatment Of Acute Uncomplicated Influenza.
Xofluza effectively treats acute uncomplicated influenza in adults aged 6 months and older, providing a new treatment option for those with resistance to adamantine-class antivirals.
Efficacy of FLU-v, a broad-spectrum influenza vaccine, in a randomized phase IIb human influenza challenge study
FLU-v, a broad-spectrum influenza vaccine, significantly reduces the risk of mild to moderate influenza disease compared to placebo in a randomized phase IIb study.
RCTRigorous Journal[Severe course of influenza B complicated by rhabdomyolysis and acute respiratory failure resulting in death].
Influenza B can cause severe muscle weakness and rhabdomyolysis, leading to acute respiratory failure and death in a 51-year-old male.
Case Report