Getting both COVID-19 and flu shots at once just as effective as separate vaccinations

Coadministration of the BNT162b2 BA.4/5 bivalent mRNA COVID-19 vaccine (BNT162b2-biv) and the seasonal influenza vaccine (SIV) offers protection against the two infections, with an efficacy that is similar as when giving each vaccine alone, according to a study.

Data from more than 3 million individuals showed that in the ≥65-year age group (n=2,210,493; mean age 75 years, 57.9 percent women), those who had the BNT162b2-biv and SIV coadministered had similar COVID-19–related hospitalization risk as those who received only the BNT162b2-biv (adjusted hazard ratio [AHR], 1.04, 95 percent confidence interval [CI], 0.87–1.24) and slightly higher risks of emergency department or urgent care encounters (AHR, 1.12, 95 percent CI, 1.02-1.23) and outpatient visits (AHR, 1.06, 95 percent CI, 1.01–1.11). [JAMA Netw Open  2023;6:e2342151]

In the 18–64-year age group (n=1,232,503; mean age 47 years, 55.4 percent women), the coadministration group had a slightly higher risks of COVID-19–related endpoints compared with the BNT162b2-biv alone group (AHR point estimate range, 1.14–1.57). However, the events were fewer overall in this age group, resulting in wider CIs.

As for influenza-related endpoints, individuals who had the BNT162b2-biv and SIV coadministered had slightly lower risks of most endpoints compared with those who received SIV alone. This was true in both age groups (≥65 years: AHR point estimate range, 0.83–0.93; 18–64 years: AHR point estimate range, 0.76–1.08).

“Negative control outcomes (ie, urinary tract infection and unintentional injury) suggested residual bias, and calibration of COVID-19–related and influenza-related outcomes with negative controls moved all estimates closer to the null, with most CIs crossing 1.00,” the investigators said.

The analyses included 3,442,996 individuals (mean age 65 years, 57.0 percent women), of whom 627,735 had the BNT162b2-biv and SIV coadministered, 369,423 had BNT162b2-biv alone, and 2,445,838 had SIV alone.

“Our community setting vaccine effectiveness results are consistent with immunogenicity data from clinical trials, which have shown that coadministration of COVID-19 and influenza vaccines does not lead to immune interference and, in some cases, may provide a stronger immune response to SIV,” the investigators noted. [Lancet 2021;398:2277-2287; Lancet Respir Med 2022;10:167-179; Infect Dis Ther 2023;doi:10.1007/s40121-023-00863-5]

“Given that there is no perfect immunologic correlate of protection for COVID-19 vaccines or for SIV, our community setting comparative effectiveness data provide important additional context to these prior immunologic studies,” they added.

The investigators are hoping that the uptake for COVID-19 vaccines and SIV—both underutilized and potentially life-saving public health interventions—will improve. By helping reassure healthcare professionals that giving these vaccines together is not only safe but also likely to yield similar effectiveness against COVID-19– and influenza-related outcomes, the study may pave the way for more successful seasonal vaccination campaigns in the years to come, they added.