The FDA recently approved the use of COVID-19 booster vaccines for both homologous and heterologous vaccine booster regimens, with both regimens considered standard of care. However, there is incomplete research on the long-term effects and immunity offered by each approach. In fact, the FDA has not offered guidance on whether or not to mix or match vaccines because as of yet, there is no evidence indicating that one strategy should be recommended over the other. Studies have shown that vaccine efficacy declines over time, and the Delta and Omicron variants continue to cause breakthrough cases. Additionally, millions of Americans are now becoming eligible for a booster. These factors present both a pressing need and a unique opportunity to investigate the longitudinal effects of the mixing and matching vaccine-booster approaches.~This study proposes to fill this critical gap through a systematic and prospective randomized trial utilizing the existing digital infrastructure of the COVID-19 Citizen Science (CCS) study on the Eureka Research Platform. Eligible CCS participants will have the opportunity to be randomly assigned to be encouraged to receive either the BNT162b2 (Pfizer) or mRNA-1273 (Moderna) booster vaccine and will continue to complete their weekly CCS follow up surveys on symptoms and infection. Thus, this study will allow for longitudinal follow up of participants receiving homologous and heterologous vaccine booster regimens. By randomizing participants and analyzing a larger cohort, this study aims to mitigate the effect of confounding variables and provide more conclusive evidence to guide booster recommendations.
While both heterologous (mixing) and homologous (matching) vaccine regimens are now considered standard of care, post-vaccination complications and long-term effects of the different vaccination regimens have not been thoroughly studied. There is a pressing need to investigate the longitudinal effects of the mixing and matching vaccine-booster approaches. This study proposes to utilize the existing digital infrastructure of the COVID-19 Citizen Science (CCS) study on the Eureka Research Platform to perform a systematic and prospective randomized trial comparing mixing versus matching approaches. Eligible CCS participants will have the opportunity to be randomly assigned to a recommendation of receiving either the Pfizer or Moderna booster vaccine. Long-term effects will be monitored through the participants' completion of their regular weekly CCS follow-up surveys on symptoms and infection. This randomized trial aims to mitigate the effect of confounding variables and provide more conclusive evidence on each regiment to guide booster recommendations.