Immunogenicity of influenza A/USSR (H1N1) subunit vaccine in unprimed young adults

Abstract

Purified subunit vaccines (HANAflu) containing 20 microgram hemagglutinin of influenza A/USSR/90/77 (H1N1) alone or with 1-5% whole virus were compared to commercially available vaccines for reactogenicity and immunogenicity in unprimed young adults. Reactions to all vaccines were minimal. Sera from volunteers who received two intramuscular doses of vaccine or placebo were tested by hemagglutination-inhibition and neutralization tests. HANAflu with 1 microgram (5%) whole virus added was not different in immunogenicity from commercial vaccine. Both commercial vaccine and HANAflu with 1 microgram whole virus added gave higher seroconversion rates and more neutralization titers greater than or equal to 4 log2 than HANAflu alone and HANAflu + 0.2 microgram (1%) whole virus. Thus, the HANAflu subunit vaccine alone was less immunogenic than commercial vaccine in unprimed persons. However, addition of 1 microgram (5%) whole virus, but not 0.2 microgram (1%), eliminated this difference, There may be a role for addition of small amounts of whole virus to subunit influenza vaccines to overcome lower immunogenicity in unprimed populations.

A randomized controlled study to evaluate the immunogenicity of a trivalent inactivated seasonal influenza vaccine at two dosages in children 6 to 35 months of age

“…Whereas the hemagglutinin surface glycoprotein provides the main antigenic stimulus, the presence of other viral components in the vaccine, such as internal proteins or RNA, could potentiate the priming of naïve immune cells. This is suggested by studies performed about 30 years ago with more highly purified subunit influenza vaccines which showed that addition of whole virus enhanced responses to subunit vaccines in children and un-primed young adults whereas addition of whole virus provided no additional benefit for primed subjects 19 - 22 …”

Evaluations for In Vitro Correlates of Immunogenicity of Inactivated Influenza A H5, H7 and H9 Vaccines in Humans

“…When the hanaflu stellate vaccines were tested with and without influenza B whole virus in humans, no enhancement in antibody responses was seen although the subjects were primed adults [52]. However, when the hanaflu/whole virus concept was tested in subjects unprimed for A/NJ/76 (H1N1) and A/USSR/77 (H1N1), enhancement was demonstrated when the hanaflu stellate vaccine included some whole virus [53], [54]. The intermediate immunogenicity of an H5N1 vaccine that contained stellate structures is compatible with the reduced immunogenicity seen in unprimed subjects with the pure hanaflu “stellate” vaccines by Webster and Laver.…”

Increased immunogenicity of inactivated influenza virus vaccine containing purified surface antigen compared with whole virus in elderly women

“…differences have not always been statistically significant. In The specificity of CTL induced by vaccination was examined contrast, split-virus vaccines are less immunogenic than WVVs by testing each population of effector cells against a panel of in immunologically unprimed subjects (1,7). It is noteworthy autologous targets that had been either infected with influenza that unlike the split-virus vaccines used in all of the previous A/Taiwan (HlNl), A/Shanghai (H3N2), or B/Yamagata virus reports referenced above, the subunit vaccine in the present or mock infected with allantoic fluid alone.…”