The recent outburst of civil unrest has, in some ways, rendered coronavirus pandemic something of an afterthought. But make no mistake: the need for a COVID-19 vaccine is still more urgent than ever—about 1,000 Americans die from the virus every day; daily new cases are still hovering at 20,000; and total cases are edging toward a ghastly two million.
Currently there are 95 experimental COVID-19 vaccines under development. About 10 of them are either entering or already in phase 1 and phase 2 trials. If everything goes well, with the occasional help of fast-track trials and expedited regulatory clearances, we will likely have a working vaccine in the next 12 to 18 months. The foremost front-runners, including two phase 2 vaccines made by Chinese pharma giant China National Biotec Group, could reach the market as soon as this year, Chinese state-run news agency Xinhua reported this week.
However, scientists caution that we might want to dial down our expectations a notch, as faster doesn’t necessarily mean better when it comes to vaccine development.
In a recent editorial in the Science Advances, immunologist Douglas J. Green, who’s also the science journal’s deputy editor, warned that rushing on clinical trials for respiratory virus vaccines, such as one for COVID-19, could be “catastrophic.”
“Many advocate ‘fast-tracking’ these trials, and some wish to rely solely on evidence of induction of neutralizing responses. However, this could be catastrophic,” Green wrote, citing the cautionary tale of a 1966 vaccine against Respiratory Syncytial Virus (RSV), a virus causing serious illness in young children, where the vaccine passed initial studies but failed during a final and large-scale human trial.
Many children participating in the trial contracted the RSV despite having taken the vaccine. Two died of the virus. Research conducted later found that the vaccine didn’t generate the necessary antibodies in patients.
“There is some reason to worry that the same may occur with some SARS-CoV-2 [COVID-19] vaccines,” Green warned.
Normally, a vaccine must go through three stages of trials before it can reach the market. Phase 1 and phase 2 trials are both tests on relatively small cohorts of patients (from 50 to a few hundred), while phase 3 trials must involve a much larger pool of people (sometimes in the thousands) and typically take several years to produce statistically significant results.
“Referring to experimental research, the eminent cancer biologist, Charles Sherr once told me, ‘Fast is slow, and slow is fast.’ This is a maxim that must be applied to vaccine development for COVID-19.”