Study Finds Influenza Vaccine’s Effectiveness Can Be Improved

Research conducted at the University of Texas at Austin found that how the influenza (flu) vaccine produces antibodies to protect against disease could be used to improve the vaccine. The findings are made possible by new technology, known as Ig-Seq, that is the first and only approach able to directly identify and quantify antibodies that are present in human blood. While there are clinical tests to help determine whether a patient has antibodies that recognize a pathogen, they are not able to determine the number, molecular identities and amounts of the different antibodies that recognize the pathogen. Identifying and quantifying antibodies is important because they allow scientists to see how the vaccine stimulates the immune system to induce the production of antibodies that may then protect against infection.

During the four-year study led by a professor in the Cockrell School of Engineering and in the College of Natural Sciences, along with a team of 34 researchers from various institutions, the serum antibody repertoire in young adults before and after seasonal flu vaccination was evaluated. Researchers discovered that after vaccination, only about 40 percent of the influenza-specific antibodies were elicited directly in response to the vaccine.

The remaining 60 percent were antibodies already present due to previous exposure or earlier circulating viruses or vaccines. They also discovered a new class of antibodies that are remarkably proficient in protecting laboratory mice against lethal challenge by influenza, yet unexpectedly do not block the virus from infecting cells. This last finding is important because all current metrics of influenza vaccine efficacy depend solely on the ability of serum to block infection and do not take into account the effect of antibodies that can protect against disease via alternate mechanisms. “In order to develop a better vaccine, you need to have a more precise, better understanding of the current vaccine’s efficacy, and to do that, you need to identify the individual antibodies that specifically bind to influenza, understand how they protect from disease and measure how long they can persist in circulation” said Jiwon Lee, a Cockrell School chemical doctoral student and first author of the study’s article.

Also during the study, the researchers investigated the relative benefits of the trivalent influenza vaccine compared with the quadrivalent vaccine, and found that about 90 percent of the antibodies elicited by one of the viruses in the trivalent vaccine also bind to the fourth virus that is now included in the newer vaccine. This raises the question of whether the adaption of the more complex quadrivalent vaccine confers an improved benefit.