Written by: Anusha Srinivasan '24
Edited by: Elizabeth Zhang '23
Flu vaccine vial, via Prefeitura Campinas, Wikimedia Commons.
Researchers have developed flu vaccines with the potential to target all strains of the flu, eliminating the need for a yearly flu vaccine. Scientists discovered an antibody in the blood of people who have previously been infected with the flu which may target multiple strains of influenza. This discovery is what may allow scientists to develop a vaccine which would be effective against many strains of influenza.
Reducing or eliminating the need for a yearly flu vaccine would have broad implications for the millions who suffer from the illness every year. Influenza is a virus with extreme global impact. In the US alone, 20 million people are infected with influenza every year, including more than 200,000 annual deaths from the virus.
Typically, people receive annual flu vaccines to ensure they are protected against whichever strain of the flu may be circulating that year. The flu virus mutates each year, meaning that protection conferred by the vaccine in one year does not guarantee protection from the flu the following year. Each year, scientists predict which strains will be dominant in circulation to develop seasonal flu vaccines. By creating a universal vaccine, scientists would avoid having to do this prediction work.
Season vaccines work to target the virus by recognizing the head of a protein called hemagglutinin, or HA. HA is a protein found on the surface of the flu virus. The head region of hemagglutinin was chosen for targeting by vaccines because this region can be easily accessed by the antibodies. However, this choice also comes with a cost. The head of hemagglutinin tends to be highly variable, meaning that a vaccine developed to target a specific strain of influenza will likely become ineffective against future strains as the hemagglutinin head continues to mutate.
In the new, experimental flu vaccines, a different region of hemagglutinin is targeted. This region, known as the stalk, extends between the flu virus and the hemagglutinin head and is much less variable in structure than the head. Because it is unlikely to mutate between various strains, a vaccine designed to target this region would likely be able to target multiple strains of the flu.
By testing the blood of people previously infected with the flu, scientists were able to identify various antibodies which target the virus. Scientists can study these antibodies which are naturally designed to target the flu virus to develop vaccines which can target the virus with similar efficacy. A particular group of antibodies which target the bottom portion of the stalk of hemagglutinin, called the anchor, shows great promise for vaccine potential. These antibodies were able to recognize many strains of H1 influenza as well as strains of H2 and H5 strains that have previously circulated in the population.
In order to develop a universal flu vaccine, scientists will likely need to find a vaccine which targets the anchor of hemagglutinin as well as other parts of the protein. This will ensure that the vaccine is effective against all strains. However, the discovery of antibodies which target a minimally variable region of the protein indicate great progress in the development of this universal vaccine. With time, scientists will likely be able to design a vaccine which eliminates the need for seasonal flu vaccines, revolutionizing the way we approach influenza in the US and globally.
1. “No More Annual Flu Shot? New Target for Universal Influenza Vaccine.” ScienceDaily, ScienceDaily, 23 Dec. 2021, https://www.sciencedaily.com/releases/2021/12/211223113049.htm.
2. [Image Citation]: Prefeitura Campinas, Wikimedia Commons. File name: Vacinação contra a gripe. Retrieved 2021, from https://www.flickr.com/photos/prefeituracampinas/51111722074/.