Patterns of co-administration and sequential administration of COVID-19 and influenza vaccinations: a US study using Adheris pharmacy dataset.

Abstract

Background: This study assessed monthly patterns of co-administration of COVID-19 and influenza vaccines at visit level and quantified the number and proportion of adults who received both vaccines on the same day or sequentially.

Research design and methods: This retrospective study utilized the Adheris pharmacy dataset and included adults aged ≥ 19 years with a record of ≥ 1 dose of COVID-19 or influenza vaccines between August 2022 and December 2023. Administration of both vaccines on the same day was defined as co-administration, and administration of vaccines within 1-180 days was referred to as sequential administration. Descriptive analyses were performed.

Results: Among 31.5 million visits with either COVID-19 or influenza vaccines, 5.8 million (18.5%) involved co-administration. Co-administration visits were higher between September and November compared to other months, rising to 1.5 million in October 2023. Among 7.9 million adults with both vaccines, 65.8% had same day administration, while 34.2% had sequential administration. 60.7% of adults with sequential administration received the vaccines within 1-30 days.

Conclusions: About one in five COVID-19 or influenza vaccinations involved co-administration. The majority of sequential administrations happened within 30 days, highlighting missed opportunities for co-administration. These findings suggest substantial potential to improve uptake of both vaccines through co-administration.