Vaccine Safety
CharLeigh Steverson, PharmD
In recent years, CDC’s ACIP has issued guidance recommending the simultaneous administration of COVID-19 and influenza vaccines for individuals who are eligible to receive both. This approach seeks to maximize vaccine coverage and streamline the vaccination process, especially considering ongoing efforts to combat both COVID-19 and seasonal influenza. While previous data have suggested that the simultaneous administration of vaccines is safe, limited randomized clinical trial data exist to fully assess the reactogenicity and safety of this strategy.
Study design and results
A randomized, placebo-controlled clinical trial conducted by Walter and colleagues and published in JAMA on November 6, 2024, aimed to fill this gap by comparing the reactogenicity, safety, and health-related quality of life (HRQOL) outcomes of simultaneous versus sequential administration of the mRNA COVID-19 vaccine and quadrivalent inactivated influenza vaccine (IIV4).
Participants were randomly assigned to one of two groups: the simultaneous group, who received both vaccines in opposite arms during the same visit, and the sequential group, to whom the vaccines were administered 1 to 2 weeks apart. The primary outcome of the study was the proportion of participants who experienced moderate or greater severity of fever, chills, myalgia, or arthralgia within 7 days after vaccination.
Secondary outcomes included the occurrence of solicited and unsolicited adverse events, serious adverse events, adverse events of special interest, and HRQOL assessed using the EuroQol 5-Dimension 5-Level Index.
The results showed that the proportion of participants experiencing the primary composite reactogenicity outcome was 25.6% in the simultaneous group, compared with 31.3% in the sequential group. The difference between the two groups was noninferior, indicating that simultaneous administration did not lead to a higher incidence of moderate or greater reactogenicity. There were no significant differences between the groups in the occurrence of adverse events, serious adverse events, or adverse events of special interest. Both groups experienced a slight decrease in HRQOL scores after vaccination, but the changes were similar between the two groups.
Impact on pharmacy practice
Pharmacists play a pivotal role in educating patients and demystifying the vaccination process. When addressing patients’ concerns about receiving two vaccines simultaneously, Walter, professor of pediatrics at Duke Human Vaccine Institute and chief medical officer at Duke University Hospital, emphasized, “Data showed similar rates of moderate or severe side effects of fever, chills, muscle pain, or joint pain whether the vaccines were given together or were given at separate visits 1–2 weeks apart.”
This reassurance is crucial for patient confidence, as many individuals may have reservations about receiving two vaccines in one visit. When counseling patients, pharmacists can reassure patients that the risk of common adverse effects is similar whether the vaccines are given together or at different times.
From a logistical standpoint, the ability to administer both vaccines simultaneously holds significant potential to positively impact pharmacy workflow. By offering patients the option to receive both vaccines in a single visit, pharmacies can enhance operational efficiency by reducing the number of patient visits and minimizing appointment scheduling complexities.
This evidence-based approach allows pharmacists to manage patient expectations regarding adverse events while encouraging a convenient, effective vaccination strategy. By focusing on patient education and addressing concerns about reactogenicity, pharmacists can help increase patient confidence, maximize vaccination rates, and optimize the overall vaccination workflow within the pharmacy setting. ■