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Flu revaccination in HCWs may prevent infection in patients
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Researchers in Norway have found that health care workers who were low responders to the pH1N1 influenza vaccine may need revaccination to maintain protection and to further decrease likelihood of nosocomial transfer of influenza to patients.
“The adjuvanted pandemic vaccine elicited protective immunity in the majority of health care workers (HCWs), but after 3 months, approximately 16% of the HCWs no longer had the protective immunity,” Rebecca Cox, PhD, head of the Influenza Center, the Gade Institute, University of Bergen in Norway, told Infectious Disease News. “Revaccination of these HCWs with a second dose of vaccine boosted the immune response so that these HCWs had long-term protection.”
According to the researchers, WHO has made it a priority for HCWs to be vaccinated to reduce transmission of influenza A(H1N1)pdm09 in the hospital. A previous study showed that a single dose of the vaccine did not elicit an antibody response sufficient enough to maintain long-term protection in 16% of those who received the vaccine.
Cox and colleagues conducted a retrospective study to evaluate the responses in 15 low responders and 25 control HCWs. Twelve of the low responders were revaccinated with the pH1N1 vaccine. The researchers then analyzed the responses after the second vaccination.
Rebecca Cox
Low responders had slower response compared with controls, as the protective hemagglutinin inhibition titers were not reached until 2 weeks after vaccination. In addition, low responders also had lower antibody-secreting cell response and lower HA1-specific serum immunoglobulin G responses. After revaccination, 11 of the 12 low responders had protective hemagglutinin inhibition antibody titers. There was also a higher influenza A(H1N1)pdm09 virus-specific IgG antibody-secreting cell response, memory B-cell response and multifunctional CD4+ T-helper 1 cell response.
“Our findings highlight the fact that the majority of HCWs were protected after pandemic vaccination, but a small, but significant, number required two doses,” Cox said. “In clinical practice, these data suggest that front-line HCWs with high risk factors be considered for a second vaccine dose during a pandemic.”
References:
Pathirana R. J Infect Dis. 2012;206:1660-1669.
For more information:
Rebecca Cox, PhD, can be reached at: Influenza Centre, The Gade Institute, University of Bergen, Laboratory Building, 5th Floor, Haukeland University Hospital, N-5021 Bergen, Norway; email: rebecca.cox@gades.uib.no.
Disclosure: Cox reports no relevant financial disclosures