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A study analysing 30-year-old blood samples of adults recently vaccinated against influenza is the first, its researchers say, to effectively look back in time to understand future immunity.<\/p>\n
Australian research published in April suggests seasonal influenza vaccination does more than protect against viruses circulating that year, being able to prime the immune system to respond to future strains, including some that emerge decades later. The study \u2014 from the Peter Doherty Institute for Infection and Immunity (Doherty Institute<\/a>) \u2014 was published in Science Translational Medicine (doi: 10.1126\/scitranslmed.aea8621<\/a>) and involved analysis of blood samples collected in 1994 from adults who had been recently vaccinated against influenza. This analysis was to track how their immune responses fared against influenza strains that circulated over the next 30 years, including influenza A (H1N1, H3N2) and influenza B.<\/p>\n What the researchers found is that the historic vaccine generated broad immune responses against future influenza strains. Immune cells that \u2018remember\u2019 past infections, antibodies and memory B cells, were able to recognise future influenza viruses, including H1N1 and influenza B. The immune system was not capable of recognising the fast-evolving H3N2 future variants, however, which the Doherty Institute said highlights why some strains are harder to protect against and why annual vaccination remains important.<\/p>\n \u201cWe found that the vaccine trained the immune system to spot parts of the virus that don\u2019t change much. Memory B cells preciously kept that information, ready for future encounters,\u201d said Research Officer in the Kedzierska Laboratory<\/a> at the Doherty Institute and co-first author on the paper Dr Isabelle Foo<\/a> from The University of Melbourne<\/a>. \u201cThis helps explain how vaccination today can protect the body for many years, unless the virus changes significantly, as seen with H3N2, which evolved enough to slip past the immune system.\u201d<\/p>\n Differences in immune responses across age groups were also revealed by the study. \u201cWe found that, because of lifelong exposure to influenza, older adults, aged 60 to 75, had more mature antibody responses able to recognise a wider range of strains, including the 2009 pandemic H1N1,\u201d said The University of Melbourne\u2019s Associate Professor Oanh Nguyen<\/a>, Principal Research Fellow also in the Kedzierska Laboratory at the Doherty Institute. \u201cHowever, both age groups mounted strong responses to the vaccine and to some future strains.\u201d<\/p>\n