An multinational team of researchers discovered that among patients hospitalized for influenza, those who were vaccinated had fewer severe illnesses, including a nearly half-reduction in the likelihood of children requiring admission to an intensive care unit.
Furthermore, the researchers discovered that fatalities among hospitalized persons aged 65 and older who had been vaccinated were 38% lower than those who had not been vaccinated.
“A common issue concerning influenza vaccination is that it is only 40-60% effective against illness, or ‘what’s the point?’
So it is important to note that although everyone in this study was hospitalized, vaccinated individuals were less likely to be severely ill or die, suggesting that you are likely to have far less severe consequences if vaccinated,” said Dr. Annette Regan, UCLA Fielding School of Public Health assistant professor of epidemiology and lead author of the peer-reviewed research, published this week in the October edition of The Lancet Infectious Diseases. “This is an important point, especially in light of the upcoming influenza season coupled with ongoing COVID-19 activity, both this season and into the future.”
Globally, influenza contributes to 9.5 million hospitalizations, 81.5 million hospital days, and 145,000 deaths each year. Vaccination offers the best method of preventing influenza illness, reducing illness in the general population by 40–60%, experts say.
Specifically, The Lancet analysis found that three groups routinely targeted for influenza vaccination experiences less severe illness. Children who had received only part of their first series of influenza vaccines had 36% lower chances of being admitted to an intensive care unit (ICU), and children who had fully completed their first series of influenza vaccines had 48% lower chances of admission to ICU compared to unvaccinated children, the researchers found.
The study – “Severity of influenza illness associated with seasonal influenza vaccination among hospitalized patients in four South American countries” – is the product of an international team of researchers from the United States, Argentina, Brazil, Chile, and Paraguay, and drew on data from all four South American countries over a period of seven years. Data were obtained through the Network for the Evaluation of Vaccine Effectiveness in Latin America and the Caribbean, influenza (REVELAC-i) which is coordinated by the Pan American Health Organization (PAHO).
“Although several studies have reported drops in influenza illness following influenza vaccination, the results have focused predominantly on adults in the United States, and this study aimed to evaluate the severity of influenza illness by vaccination status in a broad range of age groups, and across multiple South American countries,” said Dr. Marta Von Horoch, a co-author who serves as coordinator of the National Immunization Program in Paraguay. “We were very pleased to work with our partners in the U.S. and across the continent, and these findings demonstrate, quite clearly, the importance of influenza vaccination for children and adults, no matter where they live.”
The study – the first-ever on this scale in South America – examined influenza-related hospitalization rates and outcomes across all four countries from 2013-19. Specifically, the analysts reviewed the outcomes for some 2,747 patients hospitalized with confirmed influenza virus infection, in three age groups – children aged 6–24 months, adults aged 18–64 years, and adults aged 65 years or older.
Given the reality that vaccination rates have fallen, in the U.S. and globally during the COVID-19 pandemic, including among children, the findings should help make clear the benefits of timely, pro-active immunization campaigns to the public, the researchers said.
