Expert: FDA regulatory process for COVID-19 pills, child vaccination

As Pfizer and Merck & Co. Inc. seek emergency-use authorization from the U.S. Food and Drug Administration for pills to treat COVID-19, an expert at Purdue University can offer context on the regulatory process. He also can speak on next steps that must be taken for the FDA to fully approve Pfizer’s vaccine for children ages 5-11.

Expertise: Aaron Lottes worked with the FDA on the approval of drug-device combination products for 13 years. Now, as an associate professor of engineering practice in Purdue’s Weldon School of Biomedical Engineering, he continues to collaborate with the FDA and industry experts to educate the next generation of biomedical engineers and regulatory leaders.

In addition to the Q&A below, a video with Lottes’ comments on the FDA regulatory process for COVID-19 pills and vaccines has been uploaded to the AP Video Hub. All videos in the Campus Insights series are free for download and use by all AP members and can be found at apvideohub.ap.org or by doing a general search on the Associated Press site or AP Newsroom. AP members may use the video or to pull quotes for a print article.

Q: What would it mean for the FDA to authorize emergency use of a pill compared with a vaccine?

A: The FDA process for allowing emergency use of pills is really very similar to the process that the vaccines went through. Once available, just like with any other medicine, your physician would send a prescription to the pharmacy, and you would go and pick up the drug.

Also similar to the vaccines, there would likely be a phased approach in which treatment may be available to sicker patients first and then expanded to less severe patients. This reflects how the clinical studies were performed and is supported by the currently available data. Both the Merck drug (molnupiravir) and the Pfizer drug (Paxlovid) have been initially studied in patients with COVID-19 who are at increased risk of progressing to severe disease or hospitalization. Newer studies are now looking at the use of these drugs in patients at standard risk and as a prophylactic treatment to prevent the spread of COVID-19 following exposure.

Q: What are some challenges Pfizer or Merck might come across in seeking for the FDA to authorize emergency use of their pills?

A: The FDA will be rigorously reviewing the scientific integrity of the study results to determine if the available data demonstrate that the known and potential benefits outweigh the risks. The number of patients with primary results available from these clinical trials is lower than the vaccine studies – around 750 patients – but the safety and effectiveness results have been very strong. Comparable or lower rates of adverse events occurred in the treatment groups compared to the placebo groups, and the risk of hospitalization or death was reduced by 50% for the Merck drug and 89% for the Pfizer drug. This effectiveness rate is so good that additional enrollment in the Pfizer study has been stopped early to allow the study to be completed more quickly.

Moving from emergency-use authorization to full approval will be a similar pathway as for the vaccines. Initial authorization may be granted based on a subset of patients with limited follow-up, and then as the complete study results become available, a request for approval can be submitted.  Additionally, as results in lower-risk patients, as well as prophylactic results, become available, the indication and use can be expanded. The FDA is working to efficiently review the available information and an external advisory panel meeting for the Merck drug has been scheduled for Nov. 30.

It is also relevant to consider that these are not completely new drugs that have just been developed – they have been considered for antiviral use for other diseases such as SARS and MERS. But those diseases went away pretty quickly, so the incentive to further develop these antiviral drugs also went away and they were put on hold.

Q: Are there any differences in how the FDA authorized emergency use of Pfizer’s vaccine for children 5-11 years old compared with vaccines for adults and adolescents?

A: This is just like the emergency-use authorization process for the vaccines in adults and adolescents. The FDA has reviewed the currently available safety and effectiveness data and determined that there is adequate evidence to support emergency-use authorization. This was based on effectiveness results from about 2,000 children showing the vaccine was 90.7% effective in preventing COVID-19, and data from about 3,000 children showing no serious side effects were detected.

Q: What more will the FDA need from Pfizer to fully approve the vaccine for 5-11-year-olds?

A: About 4,500 children have been enrolled in this study, including children under 5 years of age. Collecting the initial results and longer-term follow-up for all of these patients is a necessary first step to move closer to FDA approval. Data from postmarket safety monitoring of adverse events, including myocarditis and pericarditis, may also help support a future approval.

Media contact: Kayla Wiles, 765-494-2432, wiles5@purdue.edu

Source: Aaron Lottes, 765-496-6024, lottes@purdue.edu