More than 13 billion doses of mRNA vaccines have been administered globally since the rollout in the United States of COVID-19 shots in December 2020 via Operation Warp Speed under the first Trump Administration.
A just-published comprehensive new review in The Lancet takes stock of what researchers around the world have learned during the past six years about the safety and efficacy of those billions of mRNA vaccine shots. The analysis by an international team of researchers takes into account the data from randomized vaccine trials, post-authorization surveillance, and active pharmacovigilance systems.
“The review concludes that serious adverse side effects from mRNA vaccines remain exceedingly rare,” notes a press release accompanying the study results.
One salient concern is that the mRNA COVID-19 vaccination increased the risk of myocarditis (an inflammation of the heart), particularly among young men. The review reports that the incidence of myocarditis was roughly 12.6 cases and 35.6 cases per million for Pfizer BioNTech’s and Moderna’s COVID-19 vaccines, respectively. However, the rate of myocarditis from COVID-19 infections was 20 to 42 times higher than from vaccination. In addition, the incidence of myocarditis from updated formulations of mRNA vaccines is no greater than the background rate.
The press release further notes:
The analysis found that across various clinical trials and real-world data, mRNA vaccines are about 87% effective against any documented SARS‑CoV‑2 infection, 93% effective against hospitalisation, and 94% effective against mortality within 14–42 days after vaccination. Effectiveness waned over time and, in some analyses, was reduced by age and against the Omicron lineage (67% against infection and 72% against hospitalisation), but booster doses helped restore protection.
The review also evaluates the potential of mRNA vaccine technologies to treat and prevent other health conditions and diseases, including influenza, Respiratory Syncytial Virus (RSV), cancer, and autoimmune conditions.
In fact, in June, a Food and Drug Administration (FDA) advisory committee unanimously endorsed a new Moderna mRNA influenza vaccine for adults 50 and older. Notoriously, FDA consideration of that same vaccine had previously been blocked in February by Vinay Prasad, then director of the agency’s Center for Biologics Evaluation and Research. The advisory panel noted that the new vaccine provokes a broader immune response than conventional seasonal flu vaccines and exerts activity against multiple strains of influenza virus. The FDA’s decision on whether to approve the new flu vaccine is expected in August.
Notably, at least 120 clinical trials are currently seeking to develop mRNA vaccines against various cancers.
Overall, The Lancet study concludes that “the accumulated evidence affirms mRNA vaccines as a safe, effective, and adaptable platform with enduring relevance for future infectious disease prevention and public health preparedness.”
