Common Side Effects of COVID-19 Vaccination
Most COVID-19 vaccine side effects are mild and transient, with systemic reactions being more common among younger individuals and after the second dose. 1
Local Reactions
- Pain at the injection site is the most common local reaction 2
- Redness and swelling at the injection site may also occur 2
Systemic Reactions
- Fatigue is one of the most frequently reported systemic side effects 2, 3
- Headache is commonly reported after vaccination 2, 3
- Myalgia (muscle pain) is a common systemic reaction 2, 3
- Fever may occur, especially after the second dose 2
- Chills may accompany fever 3
Rare but Serious Side Effects
Myocarditis
- Myocarditis risk is higher with mRNA vaccines, particularly after the second dose and in young males aged 12-29 years 1, 2
- For every 1 million males aged 12-29 years receiving a second dose of COVID-19 mRNA vaccine, approximately 39-47 cases of myocarditis would be expected 1
- Most cases of vaccine-associated myocarditis are mild and self-limiting 2
- The risk appears higher with the mRNA-1273 (Moderna) vaccine compared to BNT162b2 (Pfizer-BioNTech) 2
Anaphylaxis
- Anaphylaxis is a rare but serious allergic reaction that can occur after COVID-19 vaccination 1, 2
- The estimated rate is approximately 2.5-4.7 cases per million doses 2
- Allergic reactions may be triggered by vaccine components such as polyethylene glycol (PEG) in mRNA vaccines or polysorbate in adenoviral vector vaccines 1
Benefit-to-Risk Analysis
- The overall incidence of adverse cardiovascular effects in clinical trials has been low (<0.05%) 1
- For every 1 million males aged 12-29 years receiving a second dose of COVID-19 mRNA vaccine, while 39-47 cases of myocarditis would be expected, 560 hospitalizations, 138 ICU admissions, and 6 deaths would be prevented 1
- COVID-19 vaccines have demonstrated high efficacy in preventing symptomatic infection, hospitalization, and death 4, 5
- mRNA vaccines (Pfizer-BioNTech and Moderna) have shown the highest efficacy (>90%) in preventing symptomatic COVID-19 6, 7
Clinical Implications
- Individuals presenting with chest pain early after receiving COVID-19 mRNA vaccines should be evaluated for possible myocarditis 1
- Initial testing should include ECG, cardiac troponin measurement, and echocardiogram 1
- Adverse events occurring after COVID-19 vaccination should be reported to the Vaccine Adverse Event Reporting System (VAERS) 1
- The CDC has developed v-safe, a voluntary smartphone-based active surveillance system to monitor adverse events after COVID-19 vaccination 1
Special Considerations
- Most adverse events in immunocompromised patients are mild to moderate (grade 1 or 2) 2
- Individuals with a history of severe allergic reactions to injectable medications or vaccines should be monitored closely after COVID-19 vaccination 1
- Skin testing for PEG and polysorbate could be considered for individuals with a history of severe allergic reactions to prevent adverse events following vaccination 1
Despite the potential for side effects, the benefits of COVID-19 vaccination in preventing severe COVID-19, hospitalization, and death significantly outweigh the risks for all age and sex groups evaluated thus far 1.