Study Shows Protective Properties of Flu Vaccines

Collaborating scientists from Nationwide Children’s Hospital, Baylor Institute for Immunology Research and Mount Sinai School of Medicine have identified an important mechanism for stimulating protective immune responses following seasonal influenza vaccinations. While seasonal influenza vaccines protect 60 percent to 90 percent of healthy adults from the flu, the mechanisms providing that protection are still not well understood.

In the study, blood samples before and after influenza vaccination from three groups of healthy study participants were analyzed for antibody responses. The groups included two sets of adults, one receiving flu vaccines during the 2009-2010 winter and the other receiving vaccination during the 2011- 2012 winter, and a group of children who received the flu vaccine during the 2010-2011 winter. Analyses showed that a temporary increase in a unique subset of helper T cells expressing the co-stimulator molecule ICOS adds to the immune response by helping B cells produce influenza-specific antibodies.

Results indicated that at day seven following the administration of a flu vaccine in all groups, stimulated T cells were evident, contributing to the development of the immune response. The T cells positively correlated with increased antibodies against each flu virus strain examined, with the exception in the children’s group against the swine-origin H1N1 virus. “Given that seasonal influenza vaccines induce antibody responses mainly through boosting the recall response of the immune system, this lack of correlation might reflect the lack of H1N1 specific immunity in some children,” explained study coauthor Emilio Flano, PhD, a principal investigator in the Center for Vaccines and Immunity at Nationwide Children’s and an associate professor of pediatrics at OSU College of Medicine.

The study was published in the March 13 edition of Science Translational Medicine, a journal of the American Association for the Advancement of Science.