The Benefits Outweigh the Risks
How safe are mRNA vaccines? After billions of doses administered, a clear picture emerges.
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mRNA vaccines from Biontech/Pfizer and Moderna represented a breakthrough in combating the COVID-19 pandemic. Despite remarkable success in clinical trials, skepticism lingered among many. Recent comprehensive studies confirm previous findings: these vaccines are highly effective and safe.
With billions of doses administered, it is evident that authorized mRNA vaccines reliably protect against COVID-19 and severe disease across diverse populations, including children, pregnant individuals, and immunocompromised persons, according to researchers from the University of British Columbia and Imperial College London in a publication in The Lancet.
94% Effectiveness Against COVID-Related Deaths
The overview study systematically analyzed 68 published studies and data from various countries, concluding that mRNA vaccines demonstrate approximately 87% effectiveness against infection with the Sars-CoV-2 virus within two to six weeks post-vaccination. Effectiveness rates are around 93% for hospitalizations due to severe COVID-19 and 94% against COVID-related deaths.
After this initial period, effectiveness wanes, dropping to about 50% against infection and around 80% against hospitalization after seven to eight months. However, booster shots can significantly restore protective effects, as highlighted by the research team.
Some analyses revealed that effectiveness decreases with age and against the Omicron variant of the virus.
The Benefits Outweigh the Risks
Severe side effects are extremely rare, making the benefits of vaccination far greater than the risks, according to the authors. Among individuals receiving the Biontech/Pfizer vaccine, there were on average 12.6 cases of myocarditis or pericarditis per million doses. For the Moderna vaccine, this figure rose to 35.6 cases per million. However, the risk of these side effects is significantly lower than that associated with a COVID-19 infection, especially in male adolescents aged 12 to 19.
Most common side effects, such as fatigue, fever, or soreness at the injection site, typically resolve within a few days.
A Crucial Role for mRNA in the Pandemic
mRNA vaccines gained worldwide exposure during the COVID-19 pandemic, yet the technology has been researched for decades, primarily to mobilize the immune system against cancer.
The messenger RNA in these vaccines delivers a part of the viral genetic information into human cells, which then produce a viral protein. This stimulates an immune response, so that upon subsequent exposure, the immune system can effectively combat the virus.
Although mRNA vaccines are relatively new, they are among the most researched medications globally, as noted by the Robert Koch Institute (RKI). There is no observable risk that mRNA integrates into the DNA of body cells or germline cells, according to RKI statements.
Education and Trust are Essential
The authors of the recent study directly address widespread misinformation surrounding mRNA technology. They emphasize the necessity of providing transparent information about these vaccines to build public trust before additional mRNA products are introduced to the market.
Beyond COVID-19, mRNA technology holds great promise in medicine. Researchers are developing mRNA vaccines against influenza, RSV, and other infectious diseases, as well as mRNA-based cancer therapies.
Editor’s Recommendations
Co-author Robin Shattock from Imperial College London advocates for expanding access to mRNA vaccines in low- and middle-income countries. “Investments in technology transfer, local production, and solid regulatory systems can shorten supply chains, reduce costs, and ensure that people everywhere benefit from safe and effective vaccines, even beyond pandemics,” the researcher emphasizes.
The unequal distribution of vaccines was a heavily discussed issue during the pandemic, with poorer countries initially receiving the AstraZeneca vector vaccine, while wealthier nations secured larger quantities of mRNA vaccines early on.
