‘Science is humbling’
A similar mishap with a coronavirus vaccine “could backfire, increasing people’s skepticism about vaccines and vaccine development and their distrust of doctors,” Dr. Brit Trogen said.
“Everyone wants the vaccine to be the silver bullet that gets us out of this crisis, but intense political and public pressure to release a vaccine before the science is ready could have devastating negative consequences,” said Trogen, a pediatric resident at NYU Langone Medical Center and Bellevue Hospital in New York.
Keep in mind that if one or more of the vaccines now being tested for COVID-19 should happen to cause serious illness in even a very small percentage of people, there is still no effective cure.
Experts also worry about unwarranted expectations for the effectiveness of a vaccine. No vaccine prevents illness in 100% of recipients, though as with the flu vaccine, people who are vaccinated may end up with milder illness. One of the COVID-19 vaccines being tested would likely be able to prevent many cases of more serious, life-threatening infections, said Dr. Paul A. Offit, a world leader in vaccine development.
“Even a vaccine that is 50% effective in preventing fatal illness might be acceptable,” said Offit, professor of pediatrics and director of the Vaccine Education Center at Children’s Hospital of Philadelphia.
It is not enough to know that a candidate vaccine produces an antibody response — even a vigorous response — in susceptible people or that hundreds of volunteers inoculated with it experienced no serious adverse effects. Not until a vaccine is tested in tens of thousands of people can doctors be reasonably certain it is safe and effective, and sometimes not even then.
Under normal circumstances, this process takes years. But these are not normal times, so the testing of potential COVID-19 vaccines is being collapsed into months, which could increase the risk of foulups. However, Dr. Francis Collins, director of the National Institutes of Health, gave his word that, despite being in a hurry to get an effective vaccine to the public, “we will not compromise on safety.”
Here’s how Offit, who is involved in supervising the COVID-19 vaccine trials, described the necessary sequence of events:
A prospective vaccine is first tested on laboratory animals that normally develop COVID-19 when infected with the virus, such as mice, to see if it prevents the disease. This is called “proof of concept” that the vaccine can work. It is followed by Phase I and Phase II trials in perhaps hundreds or thousands of