When the COVID-19 pandemic swept across the globe, pharmaceutical companies including Pfizer, AstraZeneca, Moderna, and Johnson & Johnson developed vaccines at unprecedented speed. While these vaccines played a major role in reducing severe illness and death, their rapid rollout also raised questions about long-term safety.
Now, with billions of doses administered worldwide and nearly five years of follow-up data, health authorities and researchers have been able to identify and assess several confirmed adverse effects.
Confirmed but Rare Side Effects
Medical monitoring systems and large-scale studies have shown that most side effects are mild and temporary, such as fatigue, fever, or soreness at the injection site. However, some rare but documented adverse effects have been acknowledged by health agencies and manufacturers:
Myocarditis and pericarditis, primarily in younger males, particularly after mRNA vaccines