Influenza Vaccine

RIV4 and IIV4 Flu Vaccines Are Similarly Safe, Effective

Both the quadrivalent recombinant influenza vaccine (RIV4) and the quadrivalent-inactivated influenza vaccine (IIV4) are safe and effective for use among individuals age 18 to 49 years, according to a recent study.

Seasonal influenza vaccines are transitioning to quadrivalent formulations. These include the hemagglutinins of influenza A subtypes H1N1 and H3N2, and B lineages Yamagata and Victoria.

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For their study, the researchers compared the new RIV4 with the standard-dose, egg-grown IIV4 among adults age 18 to 49 years.

Co-primary endpoints for non-inferiority included hemagglutination inhibition seroconversion rates and post-vaccination geometric mean titer ratios for each antigen, based on US regulatory criteria. The safety evaluation included reactogenicity, which was solicited for 7 days; other safety events, which were recorded for 28 days; and serious or medically attended adverse events, which were recorded for 6 months.

Results indicated that the immunogenicities of RIV4 and IIV4 were similar. Additionally, the researchers found that the co-primary non-inferiority criteria had been met for 3 antigens. Additionally, the antibody responses to the antigen influenza B/Brisbane/60/2008 had been low in both groups. As a result, comparisons were unable to be interpreted.

The researchers noted that any systemic and injection site reactions were mild, transient, and similar with each vaccine. Furthermore, none of the spontaneously reported serious or non-serious adverse events were considered related to the study vaccine.

“This first head-to-head comparison of recombinant versus inactivated quadrivalent influenza vaccines in [18- to] 49-year-old adults showed comparable immunogenicity, safety, and tolerability for both vaccines,” the researchers concluded.

—Christina Vogt


Dunkle LM, Izikson R, Patriarca PA, Goldenthal KL, Muse D, Cox MMJ. Randomized comparison of immunogenicity and safety of quadrivalent recombinant versus inactivated influenza vaccine in healthy adults 18-49 years of age [Published online September 9, 2017]. J Infect Dis.