💉 A much more effective flu vaccine

Current flu vaccines primarily prevent infection in individuals, but new research led by the University of Michigan and the Institut Pasteur suggests that incorporating antibodies induced by infection could lead to the development of more effective vaccines, which would also reduce human-to-human transmission.

The influenza virus has two main surface proteins: one (called HA) allows the virus to attach to and infect cells, the other (called NA) allows it to escape and spread. Current vaccines mainly target the HA protein. The researchers show that by also boosting defenses against the NA protein, it would not only reduce infection in vaccinated individuals, but also the transmission of flu from person to person.


"NA is a relatively neglected part of the flu virus in vaccine design, whereas targeting this protein could reduce both the risk of infection and the contagiousness of an infected person," said Aubree Gordon, co-senior author of the study and director of the Michigan Center for Infectious Disease Threats and Pandemic Preparedness.

The study, published in the journal Nature Communications, was funded by the U.S. National Institutes of Health (NIH). It comes as there is alarm about very high upcoming flu activity and the first deaths of the 2025-2026 season have already been recorded in the Northern Hemisphere. Influenza infects more than one billion people and kills about 650,000 each year worldwide. Furthermore, the loss of productivity and hospitalizations associated with the flu place a heavy economic burden.

"Modifying vaccines to incorporate antibodies against NA strengthens defenses, which is particularly important for infants, immunocompromised people, and those unable to develop a strong vaccine response," said Aubree Gordon, an epidemiologist at the School of Public Health. "This modification could also be crucial in the event of an influenza pandemic."

Aubree Gordon co-led a multinational research team that followed 171 Nicaraguan households and their 664 contacts over three flu seasons: 2014, 2016, and 2017. Almost all participants had never been vaccinated, allowing researchers to observe transmission patterns primarily influenced by infection-induced antibodies.

The scientists identified the antibodies most effective in limiting spread through blood analyses, virological tests, and powerful mathematical modeling.

Simon Cauchemez, head of the Mathematical Modelling of Infectious Diseases Unit at the Institut Pasteur, is co-senior author of the study. He explained that the detailed data on households and modeling methods allowed the scientists to determine which antibodies were most effective at preventing an infected person from transmitting the flu to their close contacts.

"Understanding the factors that influence flu spread is essential for developing better containment strategies, but it often proves complex. This study provided these insights through the analysis of very detailed data, documenting flu transmission within households using state-of-the-art modeling techniques," said Simon Cauchemez.

The authors conclude: "Studying infection-induced immunity allows us to identify the most protective antibody responses and translate these findings into improved vaccines, offering stronger and longer-lasting protection".