Concomitant administration of the high-dose quadrivalent influenza vaccine (QIV-HD) and the mRNA-1273 SARS-CoV-2 vaccine booster dose is not associated with any safety concerns or interference in older adults’ immune response, according to interim results from an ongoing phase 2 clinical trial published in The Lancet Respiratory Medicine.

The multicenter, open-label, descriptive trial ( Identifier: NCT04969276) is being conducted at 6 clinical research sites in the United States. All community-dwelling adults aged 65 years or older who previously received a 2-dose primary schedule of the mRNA-1273 SARS-CoV-2 vaccine were eligible for inclusion in the study. The second dose of the primary mRNA-1273 vaccination series needed to have been administered at least 5 months prior to study enrollment.

All of the study participants were randomly assigned in a 1:1 ratio (via use of a permuted block method stratified by site and age-group [<75 years vs ≥75 years]) to receive 1 of the following: (1) concomitant administration of QIV-HD and the mRNA-1273 vaccine; (2) QIV-HD alone; or (3) the mRNA-1273 vaccine alone.

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Between July 16 and August 31, 2021, a total of 306 individuals were enrolled in the study and were randomly assigned to 1 of the 3 groups, with 296 of these persons receiving 1 dose or more (n=100 in the coadministration group, n=92 in the QIV-HD-alone group, and n=104 in the mRNA-1273-alone group). Reactogenicity profiles were similar between the coadministration and the mRNA-1273 vaccine groups, with lower reactogenicity rates reported in the QIV-HD-alone group. Solicited injection site reactions that occurred up to 7 days after mRNA-1273 vaccine injection occurred at similar rates in the coadministration group (86.0%  [86 of 100 participants]; 95% CI, 77.6-92.1) and in the mRNA-1273-vaccine-alone group (91.3% [95 of 104 participants]; 95% CI,  84.2-96.0), and at lower rates in the QIV-HD group (61.8% [55 of 89 participants]; 95% CI, 50.9-71.9).

Solicited injection site reactions reported following the QIV-HD injection in the coadministration group occurred less often than those following the mRNA-1273 vaccine injection in the coadministration group (61.0%; 95% CI, 50.7-70.6 vs 82.0%; 95% CI, 73.1-89.0 in the QIV-HD-injected limbs and the mRNA-1273-injected limbs, respectively) and at a similar rate to the QIV-HD-alone group (61.8%; 95% CI, 50.9-71.9). The frequency of solicited systemic reactions was 80.0% (95% CI, 70.8-87.3), 83.7% (95% CI, 75.1-90.2), and 49.4% (95% CI, 38.7-60.2) in the coadministration, mRNA-1273-alone, and QIV-HD groups, respectively.

Up to day 22, unsolicited adverse events (AEs) were reported among 17.0% (95% CI, 10.2-25.8) of participants in the coadministration arm and 14.4% (95% CI, 8.3 to 22.7) in the mRNA-1273-alone arm. Unsolicited AEs occurred at a slightly lower rate (ie, 10.9%; 95% CI, 5.3-19.1) among participants in the QIV-HD-alone arm.

Overall, 7 participants each reported 1 medically attended AE (3 in the coadministration arm, 3 in the mRNA-1273 arm, and 1 in the QIV-HD arm). No serious AEs, AEs of special interest, or deaths were reported. Hemagglutination inhibition antibody geometric mean titers increased from day 1 to day 22 to similar levels in the coadministration and the QIV-HD groups for each influenza strain. Additionally, SARS-CoV-2 binding antibody geometric mean concentrations also increased to levels that were similar in the coadministration and mRNA-1273 arms at day 22 (7634; 95% CI, 6445-9042 vs 7904; 95% CI, 6883-9077, respectively).

“Concomitant implementation of these vaccination campaigns could help avoid potential delays in influenza vaccination during the northern hemisphere influenza season due to prioritization of COVID-19 booster vaccination, which is particularly important among individuals at increased risk of severe illness and hospitalization from both COVID-19 and influenza infection,” the study authors wrote. “Therefore, concomitant vaccination might be needed to reduce morbidity and mortality due to these infectious diseases as much as possible.”

Disclosures: Some of the study authors have declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 


Izikson R, Brune D, Bolduc JS, et al. Safety and immunogenicity of a high-dose quadrivalent influenza vaccine administered concomitantly with a third dose of the mRNA-1273 SARS-CoV-2 vaccine in adults aged ≥65 years: a phase 2, randomised, open-label study. Lancet Respir Med. Published online January 31, 2022. doi:10.1016/S2213-2600(21)00557-9

This article originally appeared on Pulmonology Advisor