Currently, 34 vaccine candidates for the novel coronavirus are in various stages of clinical development, according to the World Health Organization (WHO). However, the process is long, typically many years. In the race for a vaccine, there is some debate on the merits of rushing through the process.
The vaccines process is long because there are 3 phases of trials. The first two trials focus on effectiveness—does the vaccine work or not. This is a relatively straightforward question and it can be proven in relatively small sample sizes. So, just a few hundred people are needed to test it. However, Phase 3 is used to prove the safety and efficacy of the vaccine—does it have significant side-effects, is it safe for people with compromised immune systems, and can everyone use it?
That means Phase 3 typically involves many thousands of people and can take a significant amount of time.
Chinese vaccines are being tested currently in Phase 3 clinical trials in several countries around the world, but are still facing the hurdles of data accuracy and patient recruitment. Some have suggested rushing through Phase 3, but this has drawn criticism from the WHO. “This Phase 3 must take longer because we need to see how truly protective the vaccine is and we also need to see how safe it is,” WHO spokeswoman Margaret Harris said during a media conference.