Seasonal Influenza Vaccination and the Heightened Risk of Coronavirus and Other Pandemic Virus Infections: Fact or Fiction?

摘要

During this ongoing severe acute respiratory illness coronavirus 2(SARS-CoV-2) pandemic, few speculative reports on significantassociation of influenza vaccines with an increased risk ofcoronavirus infection appeared both in media and academiccircles. The speculation of vaccines paradoxically increasing therisk of infections possibly originated first following 2009influenza A (H1N1pdm09) pandemic when four Canadianstudies suggested that receipt of seasonal influenza vaccineincreased the risk of laboratory-confirmed 2009 pandemicinfluenza A (H1N1pdm09) virus infection [1]. This led to fiveadditional studies, each of which substantiated these initialfindings. One proposed mechanism behind this phenomenon is‘original antigenic sin’ which was first used to describe how firstexposure to influenza virus shapes the outcome of subsequentexposures to antigenically related strains. When an individual isinfected by an ‘evolved’ strain with a new dominant antigen,slightly different from the ‘original’ strain against which theperson has been vaccinated, the immune system producesantibodies against the ‘original’ strain through preformed high-affinity memory B cells that inhibit activation of na?ve B cellsresulting in a weak immune response against the new ‘dominant’strain. Hence, the risk of infection paradoxically increased invaccinated individuals as compared to unvaccinated individuals[2].