Summary of Clinical Trials of Influenza Virus Vaccines in Adults

Abstract

Trials in approximately 3,900 adults were conducted with influenza A/New Jersey/76, A/Victoria/75, and B/Hong Kong/72 virus vaccines. Subjects were observed following a standard protocol, and serologic testing was performed in a single laboratory. The data indicate that prior experience of the population with earlier influenza viruses ("priming") is a determinant in response to vaccination. Thus, participants older than 25 years showed good serologic response following a single inoculation of A/New Jersey/76 virus, while younger persons responded poorly. Serological responses to A/Victoria/75 and B/Hong Kong/72 viruses were, in contrast, equally good in the younger and older adults. Whole-virus vaccines were measurably more reactive than split-virus vaccines, a finding more easily discernined in unprimed populations. In the unprimed persons, a single dose of split-virus vaccine was less immunogenic than a single dose of whole-virus vaccine. The presence of preexisting antibodies appeared to reduce systemic reactivity. For adequate immunization of a totally unprimed population, a single relatively large and reactive dose of whole-virus vaccine or two, properly spaced, smaller nonreactive doses of either whole-virus vaccine or split-virus vaccine would be required.

Immunogenicity of influenza A(H1N1)pdm09 vaccine in patients with diabetes mellitus

“…A second vaccination might be effective. Previous studies [25][26][27][28][29] have suggested that 2 doses of vaccine are required to elicit a protective immune response in populations that are immunologically naïve to a new influenza strain. One study 10 reported that immune responses in the elderly could be substantially boosted by a second dose of vaccine-among subjects ≥61-y-old who received a 15-μg dose of unadjuvanted A(H1N1)pdm09 vaccine, the seroprotection proportion was 79.1% at 21 d after the first dose, and 93.3% at 14 d after the second dose (35 d after first dose).…”

Kinetics of Immune Responses to Influenza Virus-Like Particles and Dose-Dependence of Protection with a Single Vaccination

“…Two doses of inactivated virus vaccines are usually recommended to immunize naïve individuals for adequate protection due to their relatively low immunogenicity (20). Therefore, development of a single-dose protective and safe vaccine would have significant advantages for application to humans.…”

Seasonal influenza infection and live vaccine prime for a response to the 2009 pandemic H1N1 vaccine

“…In addition, data from recent p-H1N1 vaccine trials suggest that a large segment of the population has been exposed to an influenza virus that "primed" individuals such that only one dose of the novel pandemic vaccine is sufficient to elicit a protective antibody titer (7)(8)(9)(10). This observation was unexpected, because studies conducted in the 1970s had shown that two doses of vaccine were needed to immunize a naïve population (11).…”