First Month of COVID-19 Vaccine Safety Monitoring - United States, December 14, 2020-January 13, 2021.
Level 4 - case-series / case-control
Descriptive post-authorization safety surveillance analysis without an unvaccinated comparison group.
PubMed 33630816 · doi:10.15585/mmwr.mm7008e3
What was done
The CDC analyzed safety data from the first month of US COVID-19 vaccination (December 14, 2020–January 13, 2021) following EUAs for Pfizer-BioNTech and Moderna vaccines. Surveillance utilized passive reporting via the Vaccine Adverse Event Reporting System (VAERS) and active smartphone-based monitoring via v-safe, focusing initially on healthcare personnel and long-term care facility residents.
What was found
Across 13,794,904 administered doses, VAERS processed 6,994 adverse event reports: 6,354 (90.8%) were classified as nonserious and 640 (9.2%) as serious. The most common symptoms were headache (22.4%), fatigue (16.5%), and dizziness (16.5%). A total of 113 deaths were reported (78 [65%] in long-term care facility residents), with clinical review finding no causal relationship to vaccination. Anaphylaxis occurred at a rate of 4.5 reported cases per million doses. In v-safe data, Pfizer-BioNTech recipients reported more frequent reactions after dose two than dose one.
Why it matters
These early real-world surveillance data provided rapid reassurance that initial rollout of mRNA COVID-19 vaccines did not generate unexpected serious safety signals in high-priority populations.
Limits
VAERS relies on spontaneous reporting, which is subject to underreporting, stimulated reporting, and incomplete data. VAERS reports cannot establish causality without controlled baseline comparisons. Active surveillance via v-safe was voluntary and required smartphone access. The population was restricted primarily to healthcare workers and nursing home residents during a single one-month window.
Cited by
- supports Under the FDA Emergency Use Authorization for COVID-19 vaccines, healthcare providers are legally required to report all serious adverse health events, including inpatient hospitalizations and deaths, to VAERS regardless of perceived causality.