COMPARISON OF SEROLOGY AND REACTOGENICITY BETWEEN INFLUENZA SUBUNIT VACCINES AND WHOLE VIRUS OR SPLIT VACCINES - A REVIEW AND METAANALYSIS OF THE LITERATURE

Currently three different inactivated influenza vaccine types are avai lable: whole virus (WV), split (SPL) and subunit (SU) vaccines. Physic ians and patients at risk for influenza complications may wonder wheth er there are important differences between the vaccine types with resp ect to antibody induction (serology) acid adverse effects (reactogenic ity). A literature review (1975 to 1995) was performed to evaluate the serology and reactogenicity of SU vaccines in comparison with either split or whole virus vaccines. 22 publications with randomised allocat ion were identified describing a total of 5416 serological observation s, 2858 observations of local reactions, and 2990 observations of syst emic reactions. Subjects included those from all age groups from child ren to the elderly. Absolute protection and reaction rate differences (RD) were calculated for the comparisons SU vs SPL or SU vs WV vaccine . These were subjected to a method of metaanalysis, resulting in poole d rate differences and their 95% confidence intervals. With the except ion of the comparison SU vs WV vaccine in subjects born after 1957 and unexposed to the reappearing H1N1 subtype after 1977, no evidence was found to suggest relevant differences in seroresponse among the three currently available inactivated influenza vaccine types. Although ins ufficient data were available in the meta-analysis for vaccines in chi ldren for whom specific recommendations concerning these vaccines exis t, adverse events after administration of any of the three vaccine typ es were generally mild and transitory; however, SU vaccines were assoc iated with a lower frequency of local and systemic reactions.