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Receipt of seasonal flu vaccine lessened response to pH1N1 vaccine
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Adults who previously received the trivalent seasonal influenza vaccine had lower immune responses to influenza A(H1N1)09pdm vaccine, according to researchers from GlaxoSmithKline.
“Although no formal statistical comparison between groups was made, our results indicate that there was a trend for diminished A(H1N1)09pdm-specific humoral and CD4+ T-cell responses following vaccination with the pandemic vaccine in subjects who had previously received [trivalent seasonal influenza vaccine],” the researchers wrote in The Journal of Infectious Diseases. “[In addition], adjuvantation of the A(H1N1)09pdm vaccine led to increased responses of vaccine-homologous and –heterologous hemagglutination inhibition antibodies, Nab and CD4+ T cells, and homologous memory B cells and plasmablasts.”
The researchers randomly assigned 133 healthy adults 1:1:1:1 to trivalent seasonal influenza vaccine (TIV) or saline. Four months later, the patients received two doses of adjuvanted or non-adjuvanted pH1N1 vaccine, given 3 weeks apart. The patients were followed until day 507 and the researchers evaluated the pre-vaccination and post-vaccination hemagglutination inhibition (HI) and neutralizing antibodies, as well as CD4+/CD8+ T cells, memory B cells and plasmablasts.
Ninety-nine of the patients completed the study. After receiving the TIV or saline, the geometric mean titers (GMTs) of pH1N1 HI antibodies remained low. Two weeks after administration of the first dose of A(H1N1)pdm09 vaccine, the GMTs increased significantly and tended to be lower among those who received TIV and higher among those who received the adjuvanted vaccine.
Three weeks after receiving the second dose of pH1N1 vaccine, the GMTs increased more among those who received the adjuvanted vaccine and remained steady in those who received the non-adjuvanted vaccine. Among patients who initially received saline, the GMTs still were higher than those who had received TIV.
Similar effects were seen with CD4+ T cells, memory B cells and neutralizing antibodies.
Disclosure: The researchers are employees of GlaxoSmithKline.
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