From the Guidelines
Yes, there is clear evidence that mRNA COVID-19 vaccines are safe, with a favorable benefit-to-risk ratio, as demonstrated by a recent study published in the Journal of the American College of Cardiology in 2022 1. The study highlights that currently approved COVID-19 mRNA vaccines are highly effective and have been shown to be safe in large-scale trials, with most reported systemic reactions being mild and transient. The incidence of adverse cardiovascular effects has been largely isolated, with an incidence of <0.05%, and there have been no reported cases of myocarditis. The rates of hypertension, bradycardia, atrial fibrillation, acute coronary syndrome, cerebrovascular events, and heart failure have been similar between vaccine and placebo arms. Another study published in the same journal in 2022 1 also supports the favorable benefit-to-risk ratio for COVID-19 mRNA vaccination, estimating that for every 1 million male individuals aged 12-29 years administered a second dose of the COVID-19 mRNA vaccine, approximately 39-47 cases of myocarditis would be expected, but 560 hospitalizations, 138 intensive care unit admissions, and 6 deaths would be prevented. Additionally, a more recent study published in the Journal of Clinical Oncology in 2024 1 emphasizes the safety and efficacy of COVID-19 vaccines in patients with cancer, highlighting that the vast majority of adverse events after COVID-19 vaccination are mild to moderate, and that vaccination has been associated with transient axillary adenopathy. Other studies published in Reviews in Medical Virology in 2022 1 also support the safety and efficacy of COVID-19 vaccines in special populations, including patients with existing comorbidities, such as cancer and neurologic disorders. Overall, the overwhelming evidence from both clinical trials and real-world use demonstrates that the benefits of vaccination in preventing severe COVID-19 illness, hospitalization, and death significantly outweigh the potential risks. Key points to consider include:
- The mRNA technology itself breaks down quickly in the body and does not alter DNA.
- The safety profile has remained consistent across diverse populations, including different age groups, pregnant women, and those with various medical conditions.
- Serious adverse events like severe allergic reactions (anaphylaxis) are extremely rare, occurring in approximately 2-5 cases per million doses.
- The vaccines underwent rigorous clinical trials before authorization and continue to be monitored through multiple safety surveillance systems.
From the Research
Safety of mRNA COVID-19 Vaccines
- The safety of mRNA COVID-19 vaccines has been evaluated in several studies, including a comparative safety study between mRNA COVID-19 vaccines and influenza vaccines 2.
- This study found that the safety profile of mRNA COVID-19 vaccines was divergent from that of influenza vaccines, with a higher risk of systematic reactions such as chill, myalgia, and fatigue, but a lower risk of neurological complications 2.
- Another study compared the pharmacology, indications, contraindications, and adverse effects of the Pfizer/BioNTech and Moderna vaccines, and found that both vaccines can cause mild adverse effects, but these reactions are reported to be less frequent in the Pfizer/BioNTech vaccine compared to the Moderna vaccine 3.
- A review of the current status of development of mRNA vaccine platforms found that real-world evidence following the deployment of global vaccination campaigns utilizing mRNA vaccines has bolstered clinical trial evidence and further illustrated that this technology can be used safely and effectively to combat COVID-19 4.
Adverse Effects of mRNA COVID-19 Vaccines
- Common adverse effects of mRNA COVID-19 vaccines include pain, redness or swelling at the site of vaccine shot, fever, fatigue, headache, muscle pain, nausea, vomiting, itching, chills, and joint pain 3.
- Rare but serious adverse effects, such as anaphylaxis or other allergic reactions, can occur after vaccinations, and are often caused by residual non-human protein, preservatives, or stabilizers in the vaccine formulation 5.
- Myocarditis, an inflammation of the heart muscle, has been reported in some mRNA vaccine recipients, particularly in young males after the second dose, but the benefits of using mRNA COVID-19 vaccines are still considered to outweigh the risks in all populations, including adolescents and young adults 6.
Risk Assessment and Management
- Risk stratification based on local and global experience can help prevent and manage COVID-19 vaccine-associated anaphylaxis and other allergic reactions 5.
- The Advisory Committee on Immunization Practices (ACIP) has determined that the benefits of using mRNA COVID-19 vaccines under the FDA's Emergency Use Authorization clearly outweigh the risks in all populations, including adolescents and young adults 6.
- Patient and provider education materials have been developed to ensure prompt recognition and management of myocarditis and other potential adverse effects of mRNA COVID-19 vaccines 6.