COVID-10 vaccine safety monitoring in US: no serious concerns

The first month of COVID-10 vaccine safety monitoring in the US has identified no serious safety concerns in patients receiving the Pfizer-BioNTech COVID-19 vaccine [tozinameran] or the Moderna COVID-19 vaccine [mRNA-1273], according to Centers for Disease Control and Prevention (CDC) findings reported in Morbidity and Mortality Weekly Report.

The monitoring indicates that safety profiles for both vaccines are reassuring; although local and systemic adverse events (AEs) were frequently reported, reports of anaphylaxis were rare.

Overall, 13 794 904 doses of the COVID-19 vaccines were administered between 14 December 2020 to 13 January 2021, and the Vaccine Adverse Event Reporting System (VAERS) received and processed 6994 reports of AEs, of which 90.8% were classified as nonserious and 9.2% were classified as serious. The most frequent AEs reported to VAERS were headache (22.4%), fatigue (16.5%) and dizziness (16.5%). A total of 113 (1.6%) deaths were reported, of which 65% were in long-term care facility residents aged 65 years or over; available information did not suggest any causal relationship between COVID-19 vaccination and death. Anaphylaxis was rare with both tozinameran and mRNA-1273 (4.5 cases per million doses). In patients who received tozinameran, AEs reported to the v-safe surveillance system were more frequent after the second dose than after the first dose.

During the first month of COVID-19 vaccinations, v-safe enrolled 1 602 065 vaccine recipients who completed at least one survey. Overall, 10 825 enrollees reported that they were pregnant at the time of vaccination, and 262 reported a positive pregnancy test after vaccination. Solicited local and systemic AEs were similar after first doses of Pfizer-BioNTech and Moderna vaccines; the most frequently reports AEs were injection site pain, fatigue, headache, muscle pain and chills. The reported rate of fever and chills was more than four times higher after the second dose of the Pfizer-BioNTech vaccine than after the first dose.

"No unexpected patterns of reactions or other safety concerns have been identified during early monitoring. CDC and FDA will continue to monitor the safety of COVID-19 vaccines to inform vaccination policy and to maintain public confidence . . . These initial findings should provide reassurance to health care providers and to vaccine recipients and promote confidence in the safety of COVID-19 vaccines," said the authors.