Medically reviewed by Susan Kerrigan, MD and Marianne Madsen
Sitting in quarantine with restricted movement and the knowledge that the coronavirus pandemic is damaging the world in more ways than one, one cannot help but wonder when a vaccine will be developed that will stop the novel coronavirus (COVID-19) in its tracks or at least halt the rapid spread of this virus.
Scientists are already racing to develop a vaccine for COVID-19—a feat that experts say is technically possible, but still may not come in time to help during this outbreak.
There are currently several groups that are working on a vaccine for COVID-19, but there is no guarantee that it will be ready before the end of the current outbreak. Experts warn that expedited timelines do not always allow for careful evaluation of the safety and efficacy of the vaccines.
All vaccines work according to the same basic principle. They present part or all of the pathogen to the human immune system, usually in the form of an injection and at a low dose, to prompt the system to produce antibodies to the pathogen. Antibodies are a kind of immune memory which, having been elicited once, can be quickly mobilized again if the person is exposed to the virus in its natural form.
Some pharmaceutical companies are using a newer vaccine technology based on specific DNA or messenger RNA (mRNA) sequences of the virus. The chosen sequence codes for a viral protein, such as one on the surface of the virus. This type of vaccine can still elicit a protective immune response in a person but, because the protein is only a small piece of the virus, it doesn’t cause illness. This differs from the traditional vaccine method that delivers small amounts of the live virus into a person in order to elicit an antibody effect. This technology could, however, elicit a side effect of causing a person to become ill. While there is a push to do things as fast as possible, it’s really important not to take shortcuts.
Scientists using this method can also start designing a vaccine as soon as they have the virus’s genetic sequence. With other older methods, they would need to work with actual virus samples in the lab.
Even if a vaccine makes it through all the rounds of testing, it is unlikely that drugmakers can manufacture enough vaccines to protect everyone who might be exposed to the virus. It’s possible that any vaccine developed would be reserved for those who are most at risk of developing critical symptoms, such as the elderly, those who have significant chronic health conditions, those who would be likely to spread the virus, and healthcare workers.
Dr. Peter Hotez, who is professor and dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston and co-director of the Texas Children’s Hospital Center for Vaccine Development, said that researchers can only speed up animal and clinical trials so much.
Clinical trials–an essential precursor to regulatory approval–usually take place in three phases. The first, involving a few dozen healthy volunteers, tests the vaccine for safety, monitoring for adverse effects. The second, involving several hundred people, usually in a part of the world affected by the disease, looks at how effective the vaccine is. The third does the same in several thousand people.
Hotez thinks scientists could develop multiple vaccine candidates for use when an outbreak happens:
“You could potentially have a coronavirus vaccine stockpiled and ready to go. Even if it’s not a perfect match—just like the flu vaccine isn’t for the flu—it could still do a lot to reduce hospitalization and mortality.”
In the meantime, there is another potential problem. As soon as a vaccine is approved, it’s going to be needed in vast quantities–and many of the organizations in the COVID-19 vaccine race simply don’t have the necessary production capacity. Furthermore, “Getting a vaccine that’s proven to be safe and effective in humans takes one at best about a third of the way to what’s needed for a global immunisation programme,” says global health expert Jonathan Quick of Duke University in North Carolina, author of The End of Epidemics. “Virus biology and vaccines technology could be the limiting factors, but politics and economics are far more likely to be the barrier to immunisation.”
In a pandemic, countries also have to compete with each other for medicines. Because pandemics tend to hit hardest in those countries that have the most fragile and underfunded healthcare systems, there is an inherent imbalance between need and purchasing power when it comes to vaccines.
This is all being debated, but it will be a while before we see how it plays out. The pandemic will probably have peaked and declined before a vaccine is available. A vaccine could still save many lives, especially if the virus becomes endemic or perennially circulating–like flu–and there are further, possibly seasonal, outbreaks. But until then, our best hope is to contain the disease as best as possible.