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Data and Safety Monitoring Boards: The Safeguards Behind COVID-19 Vaccines

scientists holding vaccines

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Key Takeaways

  • COVID-19 vaccines are being reviewed by experts during their development and before they are authorized by the Food and Drug Administration. 
  • At least two vaccine trials were paused and then restarted while experts reviewed side effects that occurred in patients to determine if those signaled a problem with the vaccines. 
  • A Black physicians’ association and governors in multiple states set up their own independent vaccine review committees to review the data available on the safety and effectiveness of authorized COVID-19 vaccines.

A lot has happened on the COVID-19 vaccine front in a short amount of time. Nine months after the pandemic began, vaccine candidates from Pfizer and BioNTech and Moderna each received emergency use authorization (EUA) from the Food and Drug Administration (FDA). AstraZeneca, which also released some vaccine efficacy data, is preparing to request FDA emergency use authorization.

While the developments are exciting, they're also scary for some. A Verywell survey released in February found that 51% of Americans say they don't plan to or aren't sure about getting a COVID-19 vaccine. Among this group, concerns about side effects and concerns about effectiveness are the most cited reasons for not wanting to get vaccinated.



Public health experts say one piece of information that should allay public fears is that the vaccines accepted by the FDA to be reviewed for emergency use authorization could not have made it that far without the oversight of a panel of scientists who are independent of the manufacturers developing the vaccine and the government officials who will approve it. These scientists are appointed members of data and safety monitoring boards (DSMB) that review clinical trials of drugs and vaccines. 

“The DSMB oversees the emerging data to protect the safety of research subjects and the integrity of the [clinical] trial,” Elliott Antman, MD, a senior physician specializing in cardiovascular medicine at Brigham and Women’s Hospital in Boston, Massachusetts, tells Verywell. “The members of the DSMB recommend if a trial should continue as planned, be stopped because overwhelming evidence of benefit or harm has been seen, or whether the investigators should modify the trial in some way.”  

According to guidelines from the National Institute of Allergy and Infectious Diseases (NIAID)—the branch of the National Institutes of Health (NIH) overseeing development of several COVID-19 vaccine candidates—a trial whose interventions may pose a risk to participants must have a DSMB.

What Is a DSMB?

NIAID defines a data safety monitoring board (DSMB) as “an independent committee that reviews interim safety and efficacy data and provides advice on continuing, modifying, or terminating the study.” 

DSMBs have existed for decades to vet new drugs and vaccines, Matthew Wynia, MD, MPH, director of the Center for Bioethics and Humanities at the University of Colorado Anschutz Medical Campus, tells Verywell. “The protocols for ensuring safety and efficacy of a study, and the safety of clinical trial participants, is well established," he says.

DSMBs and the COVID-19 Vaccine Candidates

Based on advice of their DSMBs, both AstraZeneca and Johnson & Johnson, two companies working on COVID-19 vaccines, paused clinical trials when two patients, one enrolled in each trial, experienced a serious side effect. Both trials have now resumed, based on the monitoring boards' determination that the adverse events did not indicate a problem with the vaccines in terms of either effectiveness or safety. In the case of AstraZeneca, one participant had an inflammatory response that may not have been related to the vaccine. Johnson & Johnson did not disclose the specific adverse event.  

The Moderna and AstraZeneca vaccines are both among several vaccines in development with funding from the NIH. A single DSMB has convened for all of the NIH-funded COVID-19 vaccines, with its chair chosen by NIAID director Anthony Fauci. The names of the DSMB members have been kept secret, other than the chair (whose university published his role online and then deleted it). Keeping names secret helps protect DSMB members from corporate or government pressure.

Pfizer, which did not take development money for its vaccine from the U.S. government, established its own DSMB. “The Data Monitoring Committee (DMC) consists of a chairperson and four additional members. We do not release names of DMC members,” Jessica Pitts, director of Pfizer’s global media relations, tells Verywell via email. "Four members are highly regarded current or former professors of medicine with extensive experience in pediatric and adult infectious diseases and vaccine safety. One member is a respected statistician with extensive experience in vaccine trials."

DSMB Reports So Far

Moderna: On November 16, NIAID released a press release regarding DSMB evaluation of Moderna's Phase 3 vaccine trial. "This interim review of the data suggests that the vaccine is safe and effective at preventing symptomatic COVID-19 in adults," the press release states. "The DSMB reported that the candidate was safe and well-tolerated and noted a vaccine efficacy rate of 94.5%."

Pfizer and BioNTech: On November 18, a Pfizer press release said that "to date, the Data Monitoring Committee for the study has not reported any serious safety concerns related to the vaccine," citing an efficacy rate of 95%.

What's Next?

Once a DSMB concludes its review, the FDA picks up the role of reviewing, assessing, and determining if the vaccines are safe and effective.

An FDA advisory committee met to discuss the Moderna vaccine EUA on December 17 and the Pfizer-BioNTech vaccine EUA on December 10. Both meetings were open to the public and broadcast on YouTube.

The FDA does not have to take the recommendation of the advisory committee, but usually does. During the advisory committee hearings, more specific safety and effectiveness data reviewed by the DSMBs is made public.

The FDA issued an EUA for the Pfizer-BioNTech vaccine on December 11 and an EUA for the Moderna vaccine on December 18.

Typically, medical groups and state and local governments accept the decision of the FDA regarding the effectiveness and safety of a vaccine, but the pandemic is an unusual time. Some health and government leaders are adding extra reviews to help alleviate public fears. The National Medical Association, which represents Black physicians, announced it has appointed an independent task force to review any drugs or vaccines approved under an emergency use authorization.

On December 22, the National Medical Association's COVID-19 Task Force released a statement in support of the FDA's EUAs for the Pfizer-BioNTech and Moderna vaccines. The task force announced that it had reviewed the clinical trial data and found consistent efficacy and safety and sufficient numbers and percentages of Black participants to have confidence in the health outcomes.

The governors of both California and New York announced that they were organizing independent review panels for any COVID-19 vaccines that are FDA authorized or approved.

New York's task force unanimously supported the Pfizer-BioNTech vaccine on December 10 and the Moderna vaccine on December 18.

Washington, Nevada, and Oregon joined with California to form the Western States Scientific Safety Review Workgroup, which announced support of the Pfizer-BioNTech vaccine on Dec 13 and the Moderna vaccine on December 20, finding both to be safe and efficacious in its reviews.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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  2. National Institute of Allergy and Infectious Diseases. Promising interim results from clinical trial of NIH-Moderna COVID-19 vaccine. Updated November 16, 2020.

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