Safety of mRNA COVID-19 vaccines among persons 15- years and above in Ghana: A cohort event monitoring study.

Introduction: The development of COVID-19 vaccines during the pandemic occurred with an unprecedented speed, requiring extraordinary post-approval safety monitoring to facilitate ongoing evaluation of their benefit-risk profile. In Ghana, the Food and Drugs Authority granted emergency use authorization to six of these vaccines including the two mRNA COVID-19 vaccines, namely, Pfizer-BioNTech and Moderna COVID-19 vaccines. The objective of the study was to estimate the incidence of adverse events following immunization (AEFIs) and adverse events of special interest (AESIs) in persons vaccinated with mRNA COVID-19 vaccines, and to identify factors associated with the development of AEFIs.

Methods: We conducted a prospective cohort event monitoring study in seven selected static vaccination center in six of Ghana's 16 regions. The choice of regions was based on their geographical locations and the incidence rate of COVID-19 at the time of the study. The study was conducted with people aged 15 years and older who were vaccinated with mRNA COVID-19 vaccines, including pregnant women. Study participants were recruited starting in November 2021, with the last participant followed up in August 2022. Persons vaccinated were followed up on days 1, 7, and 28 post-dose 1 and up to 91 days after dose 2. AEFIs were described with the most specific, or lowest-level, term using the Medical Dictionary for Regulatory Activities (MedDRA) version 26.1. Frequencies of AEFIs after each vaccine dose and vaccination center were determined. Cox-proportional hazard regression was used to assess the independent risk factors associated with the incidence of AEFI among the participants.

Results: Overall, 4678 persons who received Pfizer-BioNTech or Moderna COVID-19 vaccines from the seven vaccination centers were enrolled in the study. The mean age of participants was 32.9 years (SD ± 14.4). A total of 17.4 % (95 % CI: 16.3 % to 18.5 %) of participants experienced AEFI, with a higher incidence among Moderna COVID-19 vaccine recipients (20.4 %) compared to Pfizer-BioNTech COVID-19 vaccine recipients (14.0 %). The top five common AEFIs included injection site pain, headache, dizziness, fatigue, and fever. No serious AEFIs were reported during the study. Factors such as vaccination center and history of chronic medical conditions influenced the risk of experiencing an AEFI. Cox-proportional hazard regression revealed a 37 % lower risk of AEFI with the Pfizer-BioNTech COVID-19 vaccine compared to the Moderna COVID-19 vaccine.

Conclusion: The study on mRNA COVID-19 vaccines in Ghana showed that the vaccines are tolerated well with no significant safety concerns. Reports of systemic and local events were consistent with those reported in the summary of product characteristics of the two vaccines. The study's outcome showed that there were no safety issues with mRNA COVID-19 vaccines in Ghana. The results of this study can be used as a crucial advocacy tool to address vaccine hesitancy as countries plan to routinize COVID-19 vaccines. Additionally, the active monitoring study serves as a model for such studies in low- to middle-income countries (LMICs) with weak pharmacovigilance systems during future pandemics.