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Sequential vaccinations might provide "universal"-like flu protection
Each year, seasonal influenza kills tens of thousands in the U.S. and around the world. While an annual vaccine is available, a number of research teams have sought to create a "universal" vaccine, one that provides lasting immunity to multiple strains of the flu through a single shot or regiment. Now, researchers at The Wistar Institute believe they might have an alternate approach to creating a universal flu vaccine.  
“Influenza vaccines are very safe and provide good protection.  However, we need to continuously update seasonal flu vaccines because influenza viral proteins change over time,” said Scott Hensley, Ph.D., an assistant professor at The Wistar Institute and corresponding author on the study. “Since influenza viruses are constantly changing, we all have unique pre-exposure histories that depend on when we were born and the specific types of viruses that circulated during our childhood.”
Vaccines work by stimulating the immune system to produce antibody proteins against particles (called antigens) from an infectious agent, such as bacteria or a virus. The immune system saves the cells that produce effective antibodies, which then provide immunity against future attacks by the same or similar infectious agents.  Despite the availability of a vaccine, seasonal influenza typically kills 36,000 Americans, alone, and nearly a half million individuals around the world, in total. 
Most current efforts to create universal vaccines hinge on the idea of generating antibodies against a portion of the virus that is relatively unchanged year-to-year.
“Our studies demonstrate that individuals that are infected sequentially with dramatically different influenza strains mount antibody responses against a conserved region of influenza virus,” Hensley said. “Since we now know that pre-exposure events can influence vaccine responsiveness in a predictable way, we can begin to design vaccine regiments that preferentially elicit antibody responses against conserved regions of influenza virus.”
According to Hensley, one strategy would be to sequentially vaccinate children with antigenically distinct viral strains.  “Babies are born with an immunological blank slate,” Hensley said.  “We may be able to strategically vaccinate our children with antigenically diverse influenza strains to elicit antibodies against conserved viral epitopes.” 
Read the press release.
Read the article in the Journal of Experimental Medicine