Infecting volunteers with Covid-19 might speed up the race for a vaccine. But it could be risky – CNN

Usually, vaccines are developed over the course of several stages, starting with testing in petri dishes and animals. The small fraction of these that show some promise then enter several phases of human trials, where researchers administer the vaccine to an increasing number of people while monitoring the dosage and assessing side effects and efficacy.

In Phase 3 (the last phase before FDA approval), researchers separate the participants into two groups, and administer the vaccine to one group while giving the other a placebo.

Researchers typically wait several months as the participants lead their lives, going to work, seeing family members or taking public transportation. If fewer people who received the vaccine than those given the placebo end up getting infected, it is deemed effective.

Because doctors have an ethical duty to minimize harm, they generally avoid purposely infecting people with a virus. But the usual process of waiting to see how many of the participants are naturally infected takes a long time.

And if the trials are being conducted in a place where community spread is low, participants in both groups may never be exposed to the virus, and researchers would have a hard time determining whether the vaccine works.

An organization called 1Day Sooner, which advocates for the use of "human challenge" trials in the development of a Covid-19 vaccine, asks people (especially those who are young and have no underlying health conditions) to enter their names online and state that they are willing to volunteer to take part in such a trial.

On paper, this approach seems straightforward and full of potential, given that the world is desperate to develop a Covid-19 vaccine. But it is critical that the process -- along with the final product -- is as safe as possible, especially given the mistrust of science in this country and the growing anti-vaxxer movement. This novel study design raises several significant problems that have not yet been resolved.

It remains unclear whether controlled infection trials will be implemented, or how. Proponents of these trials say they might need about 100 participants for each study. If researchers took this approach for 20 studies, 2,000 people would be infected with Covid.

Most vaccine trials are designed to test whether the product leads people to develop antibodies, not whether the vaccine actually prevents infection. Even if an experimental vaccine causes someone to develop antibodies, they might not successfully trigger all the components of the body's immune system to effectively attack the virus.

A vaccine may also only be partially effective and could cause significant side effects. It might, for instance, create antibodies only in perhaps 50% or 60% of participants, and cause serious illness in 10%.

The incident has helped fuel the anti-vaxxer movement ever since.

Unfortunately, given the ever-rising costs of drugs in the US, pharmaceutical companies that end up developing a successful vaccine may charge a significant amount of money for it.

Proponents of challenge studies have also largely ignored the question of whether participants (or their family members) will be compensated if they end up with long-term medical problems or die as a result of the trial.

While we shouldn't automatically reject the possibility of human challenge trials, given the number of lives that could be saved with an early vaccine, we need to proceed very cautiously.

If we do embark on these trials, researchers should be even more selective about which experimental vaccines to use. Drug companies should also commit to making the vaccine, if it is approved, affordable for millions of people.

Researchers, should they embark on controlled infection trials, should administer the vaccine and infect only a handful of participants at a time, and check whether it's effective before giving it to additional subjects to minimize any potential damage.

Informed consent and robust guidelines for all participants is crucial, and researchers should quiz each participant to guarantee that he or she fully understands the potential risks.

We all want a safe, effective and widely available vaccine, but researchers need to ensure that participant safety is also thoroughly considered.

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Infecting volunteers with Covid-19 might speed up the race for a vaccine. But it could be risky - CNN