Simultaneous administration of flu and shingles vaccines in those 65 years and older was shown to have similar safety outcomes as separate doses, with no increase in severe reactions reported, according to a recent study.

In the randomized clinical trial, published in JAMA Network Open, researchers evaluated the safety of simultaneous administration of the adjuvanted recombinant zoster vaccine (RZV) with either the adjuvanted quadrivalent inactivated influenza vaccine (aIIV4) or high-dose inactivated influenza vaccine (HD-IIV4) in adults aged 65 years and older. The researchers randomly assigned 267 community-dwelling adults to receive RZV in combination with either aIIV4 or HD-IIV4, administered in opposite arms.

Primary outcomes focused on the incidence of severe solicited reactogenicity (grade 3) events within 8 days postvaccination. The results demonstrated a noninferior incidence of severe reactogenicity in the RZV and aIIV4 group (11.5%) compared with the RZV and HD-IIV4 group (12.5%), with an absolute difference of –1.0% (95% confidence interval = –8.9% to 7.1%). Serious adverse events (SAEs) occurred in 0.8% of the participants in the RZV and aIIV4 group and in 3.7% of the participants in the RZV and HD-IIV4 group, with no severe, lasting health effects or mortality reported.

Additional secondary measures assessed changes in health-related quality of life (HRQOL), using the EuroQol 5 Dimensions-5 Level scale, and reported no statistically significant differences between groups. Participants experiencing severe reactions showed temporary HRQOL declines, with scores returning to baseline by day 4 postvaccination. One SAE—cranial nerve III palsy—was noted in the HD-IIV4 group and deemed possibly related to the vaccine.

The findings indicated that simultaneous administration of RZV and aIIV4 in older adults could result in no statistically significant differences in adverse event frequency compared with RZV and HD-IIV4, aligning with U.S. Centers for Disease Control and Prevention guidelines for participants aged 65 years and older.

Full disclosures can be found in the published study.