Clinical trial participants experienced side effects, such as pain or swelling at the injection site, headache, body aches, low-grade fever, fatigue, muscle pain or joint. Symptoms typically resolved within 24-72 hours after the vaccination. Some participants reported that side effects were more pronounced after the second dose. In general, COVID-19 vaccine side effects have been described as more noticeable than side effects from the flu vaccine but less pronounced than side effects from the shingles vaccine.