Written by: Chaerim Kang ‘24
Edited by: Alyssa Steinbaum ‘23
On October 12th, 2020, Johnson & Johnson announced that they were pausing Phase 3 of the COVID-19 vaccine trials due to an unexplained illness in a participant. This was concerning to many, as trials from other pharmaceutical companies such as AstraZeneca and Eli Lilly had been put on hold in the past month for similar reasons . While the public anxiously waits for the development of additional reliable vaccines for this novel disease, it is important to understand how the vaccine testing process works and what the trial halts may tell us.
One of the first steps for developing a new vaccine is the pre-clinical stage, where scientists use laboratory data and animal studies to assess the safety of the candidate vaccine. Once the investigators and independent ethics committee are confident in the safety and efficacy of the vaccine, companies can move on to clinical trials .
The clinical trials involve human testing and can be divided into Phase I, II, and III. During Phase I, the vaccines are tested on a small number of healthy adult volunteers who have a lower risk of getting vaccine-related infections. If no serious issues arise, the trial moves on to Phase II .
The second phase includes several hundred volunteers from a wider group of people. People of different ages, races, ethnicities, genders, and locations are studied to test the safety and appropriate dosage of the vaccine .
In Phase III, thousands of volunteers participate in the trials to determine whether the vaccine will work in the real world. Some participants will receive the vaccine candidate, while others receive a placebo, a different vaccine, or nothing. The participants’ health conditions will be closely monitored for weeks to months to determine any side effects .
The recent pauses in the COVID-19 vaccine trials occurred in Phase III, where some participants were hospitalized for severe neurological symptoms. However, experts say that such halts are not uncommon as accidents and side effects are often expected during large clinical trials . After a thorough evaluation, Johnson & Johnson has announced that there was no clear evidence correlating the vaccine candidate and the adverse event.
Dr. Tom Freide, a biostatistician at University Medical Center Gottingen, states that the pause “shows me that people are taking safety very seriously”, and that despite the pressure to speed things up, it is important to keep up the standard . While the halting of the trials may not be the best news, perhaps it is best that the public remain patient and optimistic.
 Zimmer C. 3 Covid-19 Trials Have Been Paused for Safety. That’s a Good Thing. - The New York Times [Internet]. The New York Times. 2020 [cited 2020 Nov 11]. Available from: https://www.nytimes.com/2020/10/14/health/covid-clinical-trials.html
 McKeever A. Dozens of COVID-19 vaccines are in development. Here are the ones to follow. [Internet]. National Geographic Science. 2020 [cited 2020 Nov 11]. Available from: https://www.nationalgeographic.com/science/health-and-human-body/human-diseases/coronavirus-vaccine-tracker-how-they-work-latest-developments-cvd/
 How Do Vaccine Trials Work? - UPMC [Internet]. UPMC Whitefield Hospital. [cited 2020 Nov 11]. Available from: https://www.upmc.ie/how-do-vaccine-trials-work/
 Vaccine Testing and Approval Process | CDC [Internet]. Centers or Disease Control and Prevention. 2020 [cited 2020 Nov 11]. Available from: https://www.cdc.gov/vaccines/basics/test-approve.html