Experts Hope COVID-19 Vaccines Will Prove Safe and Effective, Yet Concerns Over Long-Term Effects Linger
At least one late-stage clinical trial will likely provide data to support the safety and efficacy of an emerging coronavirus disease 2019 (COVID-19) vaccine candidate by the end of this year, but there are concerns that the lack of long-term safety data and the rush to approve a vaccine before November could pose potential health risks to the public.
This is according to Barry Bloom, Ph.D., research professor of public health and former dean at the Harvard T.H. Chan School of Public Health, who participated in an online forum titled “The Coronavirus Pandemic: Global Race for a Vaccine” held September 15.
Even if results are able to support an emergency use authorization (EUA) for a COVID-19 vaccine by the end of 2020, Bloom noted, there will be a limited supply. Manufacturers, he argued, do not currently have the capacity to produce all the vaccines necessary for the U.S and the world at large.
“By January 2nd, there will not be enough vaccines to protect everybody, and that leads to some critical decisions of who will be prioritized to get the first vaccines,” Bloom said.
Forum moderator Michele Gershberg, the U.S. health editor for Reuters, asked Bloom whether it was realistic for a potential COVID-19 vaccine, once proven safe and effective in Phase III trials, could be considered or authorized for some people by as early as October 2020. Bloom responded that the decision as to whether a vaccine is protective and safe will depend on the study’s statistical data.
Gershberg also asked Bloom about pauses in COVID-19 trials, for which he responded: “It is unlikely that I think a vaccine will be so spectacular that there would be reason to stop the trial, but I would point out the pause in one of the vaccine trials from AstraZeneca was because of two patients that had potential serious adverse effects.”
This response was in reference to AstraZeneca’s decision earlier this month to pause a U.K. trial studying COVID-19 vaccine candidate AZD1222. While the company has since resumed the trial, it hasn’t yet released specifics on the adverse effects the two patients experienced.
“Now we know generally in clinical trials [that] this information does not have to be disclosed to the public, but I'm wondering under these circumstances, with everybody watching this race so closely, do you think that vaccine developers should think a little bit more differently about how quickly they disclose issues like this for the sake of transparency?” Gershberg asked.
Bloom responded that most late-stage trials, including those which enroll up to 30,000 people or more, expect to see at least one adverse event during the study period. Likewise, making interim data available during a non-pandemic era isn’t mandatory or always considered. This is a very special situation, he added, in which every country in the world (and their political parties) are involved in the COVID-19 vaccine race.
“I think your point is well-taken that the companies and the government should be as transparent as possible, [while] still protecting individual personal privacy and rights, to tell what they know at the earliest possible point,” he said.
When asked about the lack of U.S. involvement in a World Health Organization (WHO) initiative to raise “money to create an equitable distribution network of vaccines around the world,” Bloom noted that it is “very sad to see the U.S. withdraw from the WHO at exactly the time in the middle of a unique pandemic [and] when developing countries that do not have the capacity for the science or developing industrial production of vaccines are increasingly vulnerable and not willing to have us participate in a formal way.”
“The U.S. has been seen as the leader in global health, the leader in science, the leader in the commitment of science for the benefit of people around the world,” Bloom added. “We have withdrawn from that role, and I think that's bad for the U.S. and certainly not good for the people in low- and middle-income countries.”
Gershberg proceeded to ask Bloom about the potential of a government granting an EUA for a COVID-19 vaccine in children prior to adequate testing being conducted. Bloom responded that this will be highly unlikely considering most trials are restricted to adults and people with the highest risk of COVID-19-related mortality are over the age of 60.
“I would hope if the results [of adult COVID-19 studies] are so spectacularly clear that the injuries are minor that there will be studies immediately after approvals to show that it's safe in children,” he said. “We're lucky with COVID-19 in that children seem to be the most resistant to the adverse, serious consequences of hospitalization and death of any age group, so they're not the most vulnerable which they would be for many other infectious diseases.”
Bloom added that COVID-19 vaccines will likely face opposition by some groups of people.
“The first anti-vaccine organized society was in 1886, and it has persisted in many, many vaccines that were developed after smallpox,” he said. “There's always been a small group who preserve and fight for their independence to make decisions, rather than believe it's worth the public good to have everybody protected.”
What’s different now, he suggested, is that social media has provided these groups a pervasive platform capable of spreading disinformation and misinformation on a more massive scale.
“And we now know from other countries [that] misinformation…makes it only more difficult for people to get the information they need to make a decision,” he added.
Despite the possible backlash, Bloom stated he and his colleagues “in the scientific community are optimistic that several of these vaccines, and there are many more behind them, are going to be found to be safe and effective and be made available.” He estimated that approximately 5.6 billion doses will be required for the world population, or 200 to 250 million for the U.S.