A fourth COVID-19 vaccine candidate, began phase 3 trials on this week in the United States, Argentina, Brazil, Chile, Colombia, Mexico, Peru and South Africa. The researchers hope that they will have results by the end of the year. Testing will also occur in the United Kingdom in a separate trial.

The vaccine, developed by The Janssen Pharmaceutical Companies, a subsidiary of Johnson & Johnson, will be tested on up to 60,000 volunteers in over 200 testing sites. This is twice the size of the other U.S. vaccine trials so far. This vaccine uses a 1-dose approach and showed promising results in phase 1 and 2 trials. The other vaccines undergoing clinical testing require 2 doses. The other advantage to the J&J vaccine is its portability. If successful, this vaccine will not have to be kept frozen, just refrigerated.

There are many similar trials worldwide. In the US, Moderna, AstraZeneca and Pfizer are all holding phase 3 trials, although the AstraZeneca trial was put on hold earlier this month due to a volunteer in the UK becoming ill.

Vaccine development normally takes years, so the high number of phase 3 trials across the world for a new illness is unheard of. “Four COVID-19 vaccine candidates are in Phase 3 clinical testing in the United States just over eight months after SARS-CoV-2 was identified. This is an unprecedented feat for the scientific community made possible by decades of progress in vaccine technology and a coordinated, strategic approach across government, industry and academia,” NIAID Director Anthony S. Fauci, MD, said in a press release. “It is likely that multiple COVID-19 vaccine regimens will be required to meet the global need. The Janssen candidate has showed promise in early-stage testing and may be especially useful in controlling the pandemic if shown to be protective after a single dose.”

Are you interested in participating in a trial? This site explains what is involved and how to volunteer. The U.S. National Library of Medicine also maintains a site that lists all ongoing clinical trials.