Study findings suggest added benefit from recombinant flu vaccines
Click Here to Manage Email Alerts
Immunization with recombinant quadrivalent influenza vaccines improved antibody responses at 1 month after vaccination compared with egg-based vaccines in a randomized trial conducted among health care personnel.
“Most flu vaccines are produced by growing flu viruses in eggs. During the development of these egg-based flu vaccines, mutations can occur that may result in important small differences between the flu virus in the vaccine and the viruses circulating in the real world,” explained Fatimah S. Dawood, MD, a medical epidemiologist in the CDC’s Influenza Division.
Source: Adobe Stock.
“These mutations could result in reduced vaccine effectiveness for egg-based vaccines. Quadrivalent cell-culture-based inactivated influenza vaccines (ccIIV4) and quadrivalent recombinant influenza vaccines (RIV4) are produced using alternative methods that do not require vaccine viruses to be grown in eggs,” Dawood told Healio. “Thus, ccIIV4 and RIV4 vaccines have the potential to be more effective than egg-based vaccines against circulating influenza viruses.”
Unlike egg-based influenza vaccines, which have been around for more than 70 years, cell-based influenza vaccines include vaccine viruses that are grown in cultured cells of mammalian origin instead of in hen’s eggs, and recombinant influenza vaccines are created synthetically and also do not use chicken eggs in the production process, Dawood explained.
According to Dawood, there are few studies comparing the immune response to RIV4, ccIIV4 and standard egg-based influenza vaccines among adults aged 18 to 64 years. For their study, Dawood and colleagues conducted a randomized trial among U.S. health care personnel in this age group to understand how the immune responses elicited by RIV4 and ccIIV4 compare with responses elicited by egg-based influenza vaccines in this population.
According to the study, during the 2018-2019 influenza season, the researchers randomly assigned participants to receive ccIIV4, RIV4 or IIV4 and collected sera before vaccination and 1 month and 6 months after vaccination. They tested sera by hemagglutination inhibition for influenza A/H1N1, B/Yamagata, and B/Victoria and microneutralization for A/H3N2 against cell-grown vaccine reference viruses.
Overall, 727 participants were included, with 283 receiving ccIIV4, 202 RIV4 and 242 IIV4. The study showed that at 1 month, responses to ccIIV4 were similar to those of IIV4 by seroconversion rate (SCR), geometric mean titers (GMTs), GMT ratio and mean fold rise (MFR). However, RIV4 induced higher SCRs, GMTs, and MFRs than IIV4 against A/H1N1, A/H3N2, and B/Yamagata. The GMT ratio of RIV4 to egg-based vaccines was 1.5 (95% CI, 1.2-1.9) for A/H1N1, 3 (95% CI, 2.4-3.7) for A/H3N2, 1.1 (95% CI, 0.9-1.4) for B/Yamagata and 1.1 (95%CI 0.9-1.3) for B/Victoria. Additionally, the study showed that at 6 months, ccIIV4 recipients had similar GMTs to IIV4, whereas RIV4 recipients had higher GMTs against A/H3N2 and B/Yamagata.
“The study’s findings support a possible additional benefit from influenza vaccination with recombinant flu vaccines compared with IIV4,” Dawood said. “However, additional studies are needed to assess how these findings translate to real-world protection against influenza illness and whether these results remain consistent over multiple seasons with different vaccine strain compositions.”
Collapse
Click Here to Manage Email Alerts