Media release

From: PLOS

Author summary

Why was this study done?

• Every year, millions of people become infected with influenza viruses, which infect the airways and cause symptoms that include a fever, tiredness and weakness, general aches and pains, sore throat, and cough.
• Most infected individuals recover quickly, but some develop more severe illness such as pneumonia, and may require hospitalization.
• Influenza vaccination can prevent infections and severe disease, but decisions on how to prioritize risk groups, particularly in limited-resource settings, require a robust evidence base, including global, regional, and local data.

What did the researchers do and find?

• We conducted a systematic review to identify published articles on influenza-associated respiratory disease in hospitalized adults.
• We then aggregated the data from these articles with data collected by hospital-based influenza surveillance, to calculate a pooled estimate of the proportion of adults hospitalized with respiratory disease who are positive for influenza.
• Through this approach, we estimated that influenza was associated with 14% of acute respiratory hospitalizations among adults worldwide.
• This equates to over 5 million influenza-associated hospitalizations per year, with the highest rates among those 65 years and older.

What do these findings mean?

• Estimating the disease burden of influenza allows researchers and policymakers to better understand its global impact across different target groups and allows comparisons with other causes of morbidity and mortality.
• As global populations age, the importance of vaccinating adults, particularly older adults, is likely to increase.