Study of 6.2 Million Patients Reveals No Serious Health Effects Linked to mRNA COVID-19 Vaccines

Study of 6.2 million patients by Kaiser Permanente and CDC investigators will continue for 2 years.

Federal and Kaiser Permanente researchers who combed the health records of 6.2 million patients found no serious health effects associated with the 2 mRNA COVID-19 vaccines.

The study, published Sept. 2 in JAMA, reports the first comprehensive findings from the Vaccine Safety Datalink (VSD), which studies patient records of 12 million people in 5 Kaiser Permanente service regions, along with HealthPartners in Minneapolis, the Marshfield Clinic in Wisconsin. and Denver Health. The work is supported by the Centers for Disease Control and Prevention (CDC).

“These results from our safety oversight are reassuring,” said lead author Nicola Klein, MD, PhD, director of the Kaiser Permanente Vaccine Study Center and principal investigator of the COVID-19 Rapid Cycle Analysis of the Vaccine Safety Datalink.

“The world relies on safe and effective vaccines to end the COVID-19 pandemic. The Vaccine Safety Datalink is ideally suited to conduct this important surveillance and we will continue to monitor the safety of all vaccines that protect against COVID-19,” added Dr. Klein Toe, who is also a senior research scientist in the Kaiser Permanente Division of Research.

The study reported findings from mid-December 2020 to June 26, 2021. Some of the early findings had previously been summarized and reported at public meetings of the CDC’s Advisory Committee on Immunization Practices, although the JAMA article is the VSD’s first comprehensive report of its own. safety oversight of Pfizer and Moderna mRNA vaccines.

The analyzes compared specific health events among all COVID-19 mRNA-vaccinated people during the first 3 weeks after vaccination with health events in comparable types of patients during the 3 to 6 weeks after mRNA vaccination. The total number of people evaluated was 6.2 million for the first dose of both mRNA vaccines and 5.7 million for the second dose.

The design aims to compare patients who are as similar as possible to reduce the number of factors that could complicate the results. The authors added a comparison group of unvaccinated patients in an additional analysis.

The researchers examined 23 possible health effects, chosen because they were included in previous vaccine studies, that were of particular concern if an effect from COVID-19 was noticed during the clinical trials of COVID-19, or added after public health officials reported increasing. cases among vaccinated people. Tracked results include neurological disorders such as encephalitis and myelitis, seizures, and Guillain-Barré syndrome; cardiovascular problems such as acute myocardial infarction, stroke and pulmonary embolism; and others such as Bell’s palsy, appendicitis, anaphylaxis, and multisystem inflammatory syndrome.

Patients’ medical records were searched electronically, and analysts ran graphs of specific health outcomes to verify the medical problem and assess whether it started before or after vaccination.

Vaccine Safety Datalink researchers then applied statistical analysis to determine whether the number of incidents was above a certain threshold or ‘signal’. They concluded that none of the targeted health outcomes reached the signal, although for some results, the findings were less accurate due to the small number of cases. The authors said VSD safety oversight is underway, which will increase the accuracy of estimates for those results.

The study authors emphasized their findings on cases of confirmed myocarditis and pericarditis in young individuals, as that has become a worrying result. The VSD study identified 34 such cases in patients aged 12 to 39 years; 85% of them were male and 82% had been hospitalized (for a median of 1 day), and nearly all recovered by the time the card assessment took place. The authors calculated that in patients aged 12 to 39, there is a risk of 6.3 additional cases of myocarditis per million doses during the first week after vaccination. Other research has calculated a significantly higher risk of myocarditis from COVID-19 than from the vaccine.

“The results of this study are a great example of how seriously CDC takes vaccine safety, and how thorough and transparent we are in our safety monitoring efforts,” said Tom Shimabukuro, MD, lead vaccine safety for the COVID-19 response and the deputy director of CDC’s Immunization Safety Office. “Doing the science and communicating quickly and clearly with healthcare providers and the public is our top priority as COVID-19 vaccines continue to undergo the most intensive safety monitoring in US history. Vaccination remains the best way to protect yourself and your loved ones from a virus that has cost millions of lives.”

The VSD rapid cycle analysis for the mRNA COVID-19 vaccines will continue to monitor newly vaccinated patients for at least 2 years. Founded in 1990 and led by the CDC, Kaiser Permanente, and other health care systems, the VSD is the nation’s primary active surveillance system for vaccine safety.

Reference: “Surveillance for Adverse Reactions After COVID-19 mRNA Vaccination” by Nicola P. Klein, MD, PhD; Ned Lewis, MPH; Kristin Goddard, MPH; Bruce Brandweerman, MA; Ousseny Zerbo, PhD; Kayla E. Hanson, MPH; James G. Donahue, DVM, PhD; Elyse O. Khabanda, MD, MPH; Allison Naleway, PhD; Jennifer Clark Nelson, PhD; Stan Xu, PhD; W. Katherine Yih, PhD, MPH; Jason M. Glanz, PhD; Joshua TB Williams, MD; Simon J. Hambidge, MD, PhD; Bruno J. Lewin, MD; Tom T. Shimabukuro, MD, MPH, MBA; Frank DeStefano, MD, MPH, and Eric S. Weintraub, MPH, Sept. 3, 2021, JAMA.
DOI: 10.1001 / jama.2021.15072

The research was funded by the CDC.