Safety of simultaneous vs sequential mRNA COVID-19 and inactivated influenza vaccines

1. In this randomized clinical trial, the safety profile, including reactogenicity, was similar between the simultaneous or sequential administration of the quadrivalent inactivated influenza vaccine (IIV4) and COVID-19 vaccine.

Evidence Rating Level: 1 (Excellent) 

Getting vaccinated against influenza and COVID-19 have been associated with a decreased number of hospitalizations and deaths due to respective infections. According to the Centers for Disease Control and Prevention (CDC) it is recommended that these vaccines be given simultaneously at different anatomic sites. Due to a lack of evidence from previous studies, this study sought to provide further proof of the safety of the simultaneous vaccination recommendation.  Individuals were deemed eligible to participate if they were 5 years or older getting the primary 2-dose vaccine series, or 12 years or older receiving a booster vaccine, and intended on receiving the COVID-19 vaccine and the influenza vaccine. Individuals were excluded if they were pregnant or planned on getting pregnant within the next 3 months, and immunosuppressed individuals. All participants gave a blood sample to determine their SARS-CoV-2 serostatus. On the first visit, the participants received the mRNA COVID-19 vaccine intramuscularly. Participants were randomized in a 1:1 ratio to either receive the FDA approved inactivated influenza vaccine (IIV4) or a saline placebo vaccine. During the second visit, the individuals previously administered the IIV4 vaccine received the placebo, and the placebo group received the IIV4 vaccine. Until day 121, the study assessed serious adverse events (SAEs) and adverse events of special interest (AESIs) along with corresponding medication change. Health-related quality of life (HRQOL) was assessed pre-vaccination and daily for 7 days. After primary assessment, 335 participants (mean [SD] age, 33.4 [15.1] years) received bivalent BNT162b2 mRNA COVID-19 vaccine. After randomizing the participants, 169 were assigned to the simultaneous group, and 166 to the sequential group. Compared to the simultaneous group, the proportion of participants in the sequential group [52 participants [31.3%]) that experienced the primary reactogenicity outcome was noninferior (43 participants [25.6%]) (site-adjusted difference, -5.6 percentage points [pp]; 95% CI, -15.2 to 4.0 pp). Between the simultaneous and sequential groups, there was no significant difference in the proportion of participants that had SAEs (1 [0.6%] vs 1 [0.6%] respectively; difference, -0.01 pp [95% CI, -1.66 to -1.64 pp]) ad AESIs (19 [11.2%] vs 9 [5.4%], respectively; difference, 5.8 pp [95% CI, -0.1 to 11.7 pp]). Overall, in this randomized clinical trial comparing simultaneous versus sequential administration of the COVID-19, and influenza vaccine, safety was comparable between the two methods. 

Click to read the study in JAMA Network Open

Image: PD

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