TABLE 2. Potential harms of Pfizer-BioNTech COVID-19 vaccination: Grading of Recommendations, Assessment, Development and Evaluation — United States, September 2021.

Potential harms	Clinical trial evidence		Observational evidence		GRADE evidence type*
	No. of studies	RR (95% CI)	No. of studies	Cases per million doses; RR (95% CI); observed versus expected cases
Reactogenicity	2	4.7 (3.8–5.7)	0	No data	1
Serious adverse events†	2	1.0 (0.8–1.2)	0	No data§	2
Anaphylaxis
Persons aged ≥16 yrs, VAERS	NA	NA	1	4.7 cases per million doses¶	3
Persons aged ≥12 yrs, VSD	NA	NA	1	5.0 cases per million doses**
Myocarditis
Males and females aged 18–39 yrs, VSD	NA	NA	1	RR = 9.1 (95% CI = 2.1–48.6)††	3
Males aged 16–17 yrs, VAERS	NA	NA	1	120 cases observed versus 0–3 expected§§
Females aged 16–17 yrs, VAERS	NA	NA	1	15 cases observed versus 2 expected§§
Males aged 30–39 yrs, VAERS	NA	NA	1	40 cases observed versus 1–11 expected¶¶
Females aged 30–39 yrs, VAERS	NA	NA	1	7 cases observed versus 1–13 expected¶¶

Abbreviations: CI = confidence interval; GRADE = Grading of Recommendations, Assessment, Development and Evaluation; NA = not applicable; RR = relative risk; VAERS = Vaccine Adverse Event Reporting System; VSD = Vaccine Safety Datalink.

* GRADE evidence types: 1 = high certainty, 2 = moderate certainty, 3 = low certainty, 4 = very low certainty.

^† Considered a critical outcome in GRADE. https://www.cdc.gov/vaccines/acip/recs/grade/about-grade.html

^§ Observational evidence did not include an aggregate measure of serious adverse events. Data on specific serious adverse events identified through post-authorization safety surveillance were reviewed. Increased risk for myocarditis and anaphylaxis were observed in VAERS and VSD.

^¶ Based on VAERS passively reported cases, in persons aged ≥16 years, occurring in a 0–1-day risk interval after vaccination.

** Based on VSD chart reviewed cases of anaphylaxis, in persons aged ≥12 years, occurring in a 0–1-day risk interval after vaccination (RR = 5.0; 95% CI = 3.5–6.9).

^†† Based on VSD chart-reviewed cases of myocarditis occurring among persons aged 18–39 years after dose 2, occurring in a 7-day risk interval after vaccination (368 per million person-years) versus a 22–42 day comparison interval in vaccinated persons (48 per million person-years). Adjusted for VSD site, 5-year age group, sex, race/ethnicity, and calendar date.

^§§ Based on VAERS chart-reviewed cases of myocarditis among males and females aged 16–17 years compared with baseline expected cases in the absence of vaccination.

^¶¶ Based on VAERS preliminary reports of myocarditis among males and females aged 30–39 years compared with baseline expected cases in the absence of vaccination.