Concomitant Flu Vaccine, COVID-19 Booster in Older Adults: Safety, Immunogenicity

older male patient receives vaccine
Female nurse injecting Covid-19 Vaccine elderly patient. Healthcare worker is examining senior man in hospital. She is wearing face mask during COVID-19.
A phase 2 study assessed safety and immunogenicity of administering a high-dose quadrivalent influenza vaccine with a mRNA-1273 vaccine booster dose in older adults.

Administering the quadrivalent influenza vaccine (QIV-HD) at the same time as the SARS-CoV-2 mRNA-1273 booster vaccine is safe and produces no immune interference in adults aged 65 years and older, according to the interim results of a study published in Lancet Respiratory Medicine.

The ongoing, phase-2, open-label, descriptive trial conducted at 6 clinical research sites in the US ( Identifier: NCT04969276), adults aged 65 years and older who previously received 2 doses of the mRNA-1273 vaccine at least 5 months before enrolling in the study. Trial participants were assigned randomly (1:1:1) to 1 of 3 groups: the first group was slated to receive both the QIV-HD (Fluzone High-Dose Quadrivalent; Sanofi Pasteur; Lyon, France) and mRNA-1273 (Moderna; Cambridge, MA, USA) vaccines (the coadministration group); the second group got the QIV-HD vaccine alone; and the third received the mRNA-1273 vaccine alone. All vaccinations were administered between July 16 and Aug 31, 2021.

In all, 306 participants were eligible, and 296 received at least 1 vaccine dose, 100 in the coadministration cohort, 92 in the QIV-HD cohort, and 104 in the mRNA-1273 cohort. The researchers noted similar reactogenicity profiles in the coadministration and mRNA-1273 groups but saw lower reactogenicity rates in the QIV-HD group. The frequency of solicited injection site reactions was 86.0% (95% CI, 77.6-92.1), 91.3% (95% CI, 84.2-96.0), and 61.8% (95% CI, 50.9-71.9), respectively. The frequency of observed solicited systemic reactions was 80.0%, (95% CI, 70.8-87.3), 83.7% (95% CI, 75.1-90.2), and 49.4% 995% CI, 38.7-60.2), respectively.

Safety endpoints included the number and frequency of immediate unsolicited systemic adverse events and adverse reactions reported up to day 22. Unsolicited adverse events occurred in 17.0% (95% CI, 10.2-25.8) of individuals in the coadministration group and in 14.4% (95% CI, 8.3-22.7) of those in the mRNA-1273 group. Such events were noted at a slightly lower rate 10.9% (95% CI, 5.3-19.1) in the QIV-HD participants. A total of 7 participants reported 1 medically attended adverse event each (3 in the coadministration group, 1 in the QIV-HD group, and 3 in the mRNA-1273 group). No serious adverse events, adverse events of special interest, or deaths occurred. Solicited systemic reactions ranged from fatigue, malaise, and myalgia to headache. Unsolicited adverse events included hypertension and injection site reactions.

To characterize the hemagglutination inhibition antibody response, the authors reported hemagglutination inhibition antibody geometric mean titers. From day 1 to day 2, titers went up in the coadministration and QIV-HD groups to comparable levels for each influenza strain (A/H1N1: 363 [95% CI, 276-476] vs 366 [272-491]; A/H3N2: 286 [95% CI, 233-352] vs 315 [95% CI, 257-386]; B/Yamagata: 429 [95% CI, 350-525] vs 471 [95% CI, 378-588]; B/Victoria: 377 [95% CI, 325-438] vs 390 [95% CI, 327-465] respectively). SARS-CoV-2 binding antibody geometric mean concentrations also rose to comparable levels in the coadministration and mRNA-1273 groups at day 22 (7634 [95% CI, 6445-9042] and 7904 [95% CI, 6883-9077], respectively).

“This is the first study to our knowledge to suggest acceptable safety and immunogenicity of concomitant administration of a booster dose of COVID-19 vaccine with high-dose quadrivalent influenza vaccine in older adults, who are a priority target group,” the authors wrote. They also think concomitant implementation of these vaccination campaigns “could help minimize potential disruption to the seasonal influenza vaccination campaign and maximize protection against both diseases among individuals at risk of severe disease and hospitalization.”

Disclosure: Multiple authors declared affiliations with the pharmaceutical company, Sanofi Pasteur. Please refer to the original article for a full list of 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 February 1, 2022. doi:10.1016/S2213-2600(21)00557-9

This article originally appeared on Pulmonology Advisor