COVID epidemiology explained: Vaccine development
November 16, 2020 5:00 PM
Eddie Gisemba, Director of Health Promotion for Students
In the past week, we’ve heard some positive news regarding the development of a COVID-19 vaccine by the pharmaceutical company Pfizer. There is also a second viable vaccine by Moderna, which reportedly has an even higher success rate.
Our history with pandemics indicates that herd immunity is one of the most successful ways to end a pandemic. Herd immunity is acquired in one of two ways: either a large segment of the population gets a virus and recovers from it, or an effective vaccine is discovered and administered. A vaccine is the better option because fewer people contract the virus, and it protects the older, more vulnerable population.
On November 9, Pfizer published an article stating that their vaccine candidate is 90 percent effective in preventing COVID-19 among clinical trial participants. These are the results from Phase 3 of the clinical trial; so the drug has already cleared the hurdles of indicating that it exhibits safety and efficacy for human consumption. This study enrolled more than 40,000 participants, and fewer than 100 of them became infected with the virus.
Pfizer plans to submit an application for Emergency Use Authorization (EUA) to the Food and Drug Administration as soon as ‘‘required safety milestones are achieved, which is currently expected to occur in the third week of November.‘‘ The EUA is intended to make the vaccine available for widespread use as quickly as possible. With COVID-19 cases spiking in the United States, there is a clear benefit to mobilize a vaccine as quickly as possible.
On November 16, Moderna announced that its Phase 3 vaccine trial has a 94.5 percent efficacy rate. The study enrolled more than 30,000 participants in the United States and was conducted in collaboration with the National Institutes of Health and the U.S. Department of Health and Human Services. Like Pfizer, Moderna intends to submit a EUA in the coming weeks, and also plans to submit applications to global regulatory agencies.
From a public health perspective, we should practice cautious optimism until the FDA clears the Emergency Use Authorization.
According to the University of Minnesota’s Center for Infectious Disease Research and Policy, vaccine acceptance is highly dependent on its efficacy in the trials. Among survey respondents, vaccine acceptance is 61 percent if the efficacy in trials is 90 percent. Unfortunately, that is still below the 70 percent vaccine coverage needed for herd immunity.
It’s clear that individuals are a significant factor in efforts to control the pandemic. Outside of wearing masks in public and social distancing, we also need to factor in the companies making the vaccines, our trust in the FDA in clearing them, and in the end our individual agency in being among the 61 percent of respondents willing to take it.