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• Researchers from the University of Pittsburgh identified a new class of antibodies capable of combating multiple forms of the flu virus.
• Scientists believe these new antibodies could create a flu vaccine with broader protection for different strains.
• While the flu may not be a big health concern for many people, it can be for certain groups.
• Annual influenza vaccines are recommended for everyone, especially those in high-risk groups.
• Because influenza viruses are very diverse, the current vaccine tends to work better for certain strains and is less effective against others.

For most people, coming down with influenza — more commonly known as the flu — is not a major health issue. They will feel sick for four to seven days, then symptoms will subside.

However, there are populations where the flu can cause more serious health concerns, including older adults over the age of 65, pregnant people, children under the age of 5, and people with certain medical conditions such as heart disease, diabetes, and asthma.”

This is why groups like the Centers for Disease Control and Prevention (CDC) in the United States and the European Centre for Disease Prevention and Control recommend people get an annual influenza vaccine, especially those in high risk groups. A recent CDC health advisory warned that current vaccination rates against respiratory viruses are low in the U.S.

Because influenza viruses are always changing, influenza vaccines are changed yearly to protect against the strains predicted to be the most prevalent during flu season.

Additionally, influenza viruses are very diverse. For example, influenza A viruses, which contribute to seasonal epidemics each year along with influenza B, can be further divided into various subtypes before eventually being classified as individual strains. The flu vaccine works better for certain strains and is less effective against others.

Now, researchers from the University of Pittsburgh have identified a new class of antibodies capable of combating multiple flu virus subtypes.

Scientists believe this new research — published December 21 in the journal PLOS Biology — could help develop a flu vaccine with broader protection across different strains.

How do flu antibodies work?

According to Dr. Kevin McCarthy, assistant professor of microbiology and molecular genetics at the Center for Vaccine Research at the University of Pittsburgh and senior author of this study, although antibodies provide the strongest protection against flu virus infection, the virus continually evolves to escape them.

“Multiple co-circulating flu subtypes make it difficult to get a match between circulating viruses and components in vaccines,” Dr. McCarthy told Medical News Today.

“The antibodies in our study are capable of blocking multiple flu virus subtypes at once.”

Although all approved influenza vaccines train the immune system to make antibodies against the flu virus for future encounters, he explained that the influenza virus evolves to evade these antibodies, which is why updated vaccines are needed.

“The antibodies we identified demonstrate that the hurdles to making improved vaccines that resist year-to-year changes may be lower than previously believed. We also highlight that specific vaccine manufacturing processes may introduce errors that may ‘distract’ the immune system from achieving an optimal response.”

— Dr. Kevin McCarthy, senior study author

Alternatives to egg-based flu vaccines

For this study, Dr. McCarthy and his team focused on finding a new to neutralize a small change found in some H1 flu subtypes that affect the sequence of building blocks that make up hemagglutinin — a type of protein that binds receptors on red blood cells to initiate the early stage of a viral infection.

According to scientists, while certain antibodies can stop H1 and H3 flu subtypes, they are no longer able to when the hemagglutinin is modified.

Using blood samples, researchers uncovered a new class of antibodies capable of destroying certain H3 flu strains and certain H1 flu strains with or without the hemagglutinin modification.

“We have two major findings,” Dr. McCarthy reported.

“First, it appears that some humans can produce strong antibody responses that block infection by multiple influenza subtypes. A proper series of exposures is likely required but the barriers to achieving these responses are lower than we anticipated. With this information, improved vaccines can be designed and tested in the laboratory.”

“Second, some types of vaccine production like growing vaccines in eggs can introduce changes that misdirect antibodies from their intended targets, the viruses transmitting between people,” he added.

“Transitioning away from egg-grown vaccines, for which there are already alternatives, would minimize this issue.”

New flu antibodies could offer greater protection

MNT also spoke about this study with Dr. David Cutler, a board certified family medicine physician at Providence Saint John’s Health Center in Santa Monica, CA.

Dr. Cutler said the discovery of a new type of antibody to protect against influenza offers promise to reduce the disease and death caused by various flu viruses.

“Whereas some viral diseases, like smallpox, polio, and measles, have either been eradicated or markedly reduced in their impact by vaccines, influenza continues to kill thousands in this country every year,” he explained.

“What has made influenza more difficult to prevent is the rapid mutation of the virus, especially at certain sites, designated hemagglutinin and neuraminidase. These sites give the flu virus its classic designation, such as H1N1, or H3N2. Presumably, antibodies (that) latch onto more sites (that) have less variation could be more widely effective in protecting against the flu. This is the promise offered by this new class of antibodies.”

— Dr. David Cutler, family medicine physician

Can the flu be eradicated?

Despite the positive potential for this research, Dr. Cutler cautioned there are many limitations to the promise that finding this new class of antibodies produced by vaccines will lead to the eradication of influenza.

“Flu vaccines have never been more than about 50% effective in preventing serious illness or hospitalization,” he added.

“But certainly, there is room for improvement in flu vaccine development and administration. The same is true of other serious viral respiratory infections like COVID and RSV.”

Dr. Cutler also said there are limitations in terms of people not believing they need to be vaccinated and that simply having antibodies against a virus does not necessarily mean that you will not become infected or ill from that virus.

“There are many other components of the immune system (that) aid us in warding off infection in addition to antibodies,” Dr. Cutler continued.

“We are a long way from understanding all the complexities of the immune system which determine why some people acquire infections while others don’t despite having similar vaccine and disease histories.”

“Goals for future vaccine research include making them more effective at actually preventing infection, making them more resilient to mutations in viruses, and getting people more receptive to vaccine administration to prevent serious illness, hospitalization, and death,” Dr. Cutler added.