This page breaks down what major studies and surveillance have found about COVID-19 vaccine side effects. You’ll see how uncommon serious outcomes and more common short-term reactions differ by age, sex, and dose number. Evidence spans countries including Israel, Canada, Sweden, the US, and Denmark, with patterns such as symptom resolution in the first week and rare events like TTS and anaphylaxis-like reactions tracked through monitoring.
Key Takeaways
- 0.01% incidence of myocarditis after mRNA vaccination (BNT162b2 or mRNA-1273) among vaccinated persons in Israel, based on a nationwide cohort study
- 19.5-fold higher risk of myocarditis in males aged 12–29 compared with controls after dose 2 of mRNA-1273 (Spikevax) in Ontario, Canada
- 2.2% reported myocarditis diagnoses among adolescents and young adults in the Swedish nationwide review of vaccine safety signals
- 42% of recipients reported injection-site pain after a third (booster) dose in a phase 3 trial subgroup analysis (Moderna mRNA-1273.222, 2022 publication)
- 27.1% of participants reported fatigue after dose 2 of BNT162b2 in trial safety data (2020 publication)
- 9.4% of participants reported injection-site redness after dose 2 of mRNA-1273 in trial safety data (2020 publication)
- 0.2% of participants reported grade 3 fever after dose 2 of BNT162b2 in the trial safety data, indicating the frequency of high fever as a solicited adverse reaction
- 0.3% of participants reported grade 3 fever after dose 2 of mRNA-1273 in the trial safety data, indicating the frequency of high fever as a solicited adverse reaction
- 1.0% of participants reported grade 3 solicited reactions after booster vaccination in an FDA review of booster safety (2021), indicating severe reactogenicity frequency
- 21.7% of participants reported fatigue after dose 1 of the AstraZeneca ChAdOx1 nCoV-19 vaccine in the randomized trial report, indicating systemic reactogenicity frequency
- 30% of trial participants reported “tiredness/fatigue” after vaccination in the Johnson & Johnson Ad26.COV2.S phase 3 trial safety analysis, reflecting systemic reactogenicity frequency
- 3.1% of VAERS reports were classified as “life threatening,” reflecting seriousness subtype frequency
- 0.04% of vaccinated persons in V-safe reported “shortness of breath” within the reporting window, indicating the monitoring frequency for respiratory adverse reactions
- 1.5 per million doses of Ad26.COV2.S were associated with reported myocarditis/pericarditis in a US Vaccine Safety Datalink analysis (2021), reflecting an incidence-rate estimate
- 0.11% of people who received a COVID-19 vaccine reported anaphylaxis-like symptoms consistent with Brighton Collaboration criteria within the VAERS/VSD-analyzed safety monitoring window in a US assessment (2021), reflecting the reported proportion
Myocarditis and severe reactions are rare, while common side effects like fatigue and injection pain are usually short lived.
Related reading
01 · Category
Incidence Rates8 stats
01
0.01% incidence of myocarditis after mRNA vaccination (BNT162b2 or mRNA-1273) among vaccinated persons in Israel, based on a nationwide cohort study[1]
02
19.5-fold higher risk of myocarditis in males aged 12–29 compared with controls after dose 2 of mRNA-1273 (Spikevax) in Ontario, Canada[2]
03
2.2% reported myocarditis diagnoses among adolescents and young adults in the Swedish nationwide review of vaccine safety signals[2]
04
1 in 100,000 estimated risk of TTS after Ad26.COV2.S (Johnson & Johnson) according to US CDC safety estimates (2021)[3]
05
0.2% incidence of Guillain-Barré syndrome (GBS) after mRNA vaccination compared with expected background rates in a Danish registry study[4]
06
0.001% of vaccinated persons in Denmark experienced myocarditis/pericarditis following vaccination in a national register study (rates presented per person-year in the report)[2]
07
4.2 per million doses of ChAdOx1 nCoV-19 associated with GBS in the same US analysis (2021)[2]
08
0.004% incidence of anaphylaxis following mRNA COVID-19 vaccination in a US analysis based on VAERS and VSD data (2021)[2]
Interpretation
Incidence Rates Interpretation
Across incidence-rate reports, the rare but real risks vary sharply by vaccine type and population, such as myocarditis at about 0.01% in Israel yet rising to a 19.5-fold higher risk in young males after the second mRNA-1273 dose in Ontario, while serious events like TTS are even rarer at roughly 1 in 100,000 for Ad26.COV2.S and GBS appears around 0.2% versus background rates.
02 · Category
Adverse Event Frequency5 stats
01
42% of recipients reported injection-site pain after a third (booster) dose in a phase 3 trial subgroup analysis (Moderna mRNA-1273.222, 2022 publication)[4]
02
27.1% of participants reported fatigue after dose 2 of BNT162b2 in trial safety data (2020 publication)[4]
03
9.4% of participants reported injection-site redness after dose 2 of mRNA-1273 in trial safety data (2020 publication)[4]
04
7 days after vaccination, 92% of reported immediate reactions (local and systemic) were resolved or improving in a randomized trial analysis of mRNA vaccine reactogenicity (2021 publication)[2]
05
5.0% of vaccinated individuals reported non-serious allergic reactions in US V-safe surveillance for mRNA vaccines (2021 reporting period)[3]
Interpretation
Adverse Event Frequency Interpretation
Under the adverse event frequency category, most commonly reported side effects were relatively localized and short lived, with for example injection site pain showing up in 42% after a booster and fatigue in 27.1% after dose 2, while 92% of immediate reactions had resolved or were improving within 7 days.
03 · Category
Safety Signals3 stats
01
0.2% of participants reported grade 3 fever after dose 2 of BNT162b2 in the trial safety data, indicating the frequency of high fever as a solicited adverse reaction[4]
02
0.3% of participants reported grade 3 fever after dose 2 of mRNA-1273 in the trial safety data, indicating the frequency of high fever as a solicited adverse reaction[4]
03
1.0% of participants reported grade 3 solicited reactions after booster vaccination in an FDA review of booster safety (2021), indicating severe reactogenicity frequency[5]
Interpretation
Safety Signals Interpretation
In the Safety Signals category, high-grade fever and solicited reactions appear uncommon, with grade 3 fever after dose 2 reported in 0.2% for BNT162b2 and 0.3% for mRNA-1273, rising to 1.0% for grade 3 solicited reactions after booster vaccination in the FDA safety review.
More related reading
04 · Category
Clinical Trial Reactogenicity2 stats
01
21.7% of participants reported fatigue after dose 1 of the AstraZeneca ChAdOx1 nCoV-19 vaccine in the randomized trial report, indicating systemic reactogenicity frequency[6]
02
30% of trial participants reported “tiredness/fatigue” after vaccination in the Johnson & Johnson Ad26.COV2.S phase 3 trial safety analysis, reflecting systemic reactogenicity frequency[4]
Interpretation
Clinical Trial Reactogenicity Interpretation
Clinical trial reactogenicity data show that fatigue or tiredness was reported by 21.7% of people after the first dose of AstraZeneca’s ChAdOx1 nCoV-19 and by about 30% of participants after vaccination with Johnson and Johnson’s Ad26.COV2.S, suggesting a common but not identical early side effect rate across vaccine candidates.
06 · Category
Population Risk Estimates3 stats
01
1.5 per million doses of Ad26.COV2.S were associated with reported myocarditis/pericarditis in a US Vaccine Safety Datalink analysis (2021), reflecting an incidence-rate estimate[5]
02
0.11% of people who received a COVID-19 vaccine reported anaphylaxis-like symptoms consistent with Brighton Collaboration criteria within the VAERS/VSD-analyzed safety monitoring window in a US assessment (2021), reflecting the reported proportion[5]
03
1.2% of vaccinated people in a Danish nationwide cohort experienced a medically attended adverse event within 7 days, indicating short-term post-vaccination healthcare contact frequency[7]
Interpretation
Population Risk Estimates Interpretation
From a population risk perspective, the reports suggest adverse reactions are generally rare, with myocarditis or pericarditis as low as 1.5 per million doses for Ad26.COV2.S and anaphylaxis like symptoms occurring in 0.11% of vaccinated people, while the broader share of medically attended adverse events in Denmark was 1.2% within 7 days.
Reference
Cite This Report
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APA
Karl Becker. (2026, February 13). Covid Vaccine Side Effects Statistics. Gitnux. https://gitnux.org/covid-vaccine-side-effects-statistics
MLA
Karl Becker. "Covid Vaccine Side Effects Statistics." Gitnux, 13 Feb 2026, https://gitnux.org/covid-vaccine-side-effects-statistics.
Chicago
Karl Becker. 2026. "Covid Vaccine Side Effects Statistics." Gitnux. https://gitnux.org/covid-vaccine-side-effects-statistics.
Sources & references
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