Coronavirus vaccine will come with challenges and cautions, and we'll still need to be careful while it proves itself, experts say

By Melissa Patrick

Kentucky Health News

Even after a vaccine is approved for the novel coronavirus and is widely distributed, it will still be important to follow public-health recommendations to thwart the spread of the virus, including basic hand hygiene, social distancing and wearing a mask. 

Dr. Kevin Kavanagh

That's partly because the vaccine only has to be 50 percent effective at preventing covid-19, and the immunity it provides could last only a few months, says Dr. Kevin Kavanagh, a retired Somerset physician who heads Health Watch USA, which focuses on infection control. 

Because the vaccine will have been approved through an emergency-use authorization, which involves a less rigorous approval process than that of the U.S. Food and Drug Administration, Kavanagh said there will still be some unknowns about the vaccine, like what the degree or the length of its protection will be or what its long-term effects will be, especially among high-risk populations, such as those who are pregnant or immuno-suppressed.

"Emergency-use authorizations, because they're not as rigorous in evaluation, will not guarantee effectiveness or even safety compared to what a full approval process does," Kavanagh said in an intreview. "So even if you get the vaccine, you still need to wear a mask and you still need to social distance." 

Kavanagh wrote in Infection Control Today about some of the vaccine concerns that were voiced by health officials at an Oct. 22 FDA meeting, and discussed many of them with Kentucky Health News.

Some concerns are about vaccine storage and administration. Two of the vaccines that appear to be the furthest along in the development require "ultra-cold storage." Some vaccines will require two doses, and will not be interchangeable, so patients will have to make sure they receive the same vaccine for each dose.

The vaccines needing ultra-cold storage "are going to be problematic," he said. "Just manufacturing the dry ice, getting the types of glass containers that won't break, keeping them ultra-cold . . . There's just a number of problems that have to be overcome; and overcoming them doesn't mean we have to develop new technologies to do it, it's just that they don't have enough of the products. . . . There's just a lot of coordination which needs to be done."

Other concerns have to do with safety, Kavanagh said. The final phase of the accelerated vaccine trials only have 3,000 participants, 1,500 who are getting the vaccine and 1,500 who serve as the control group.

Also, the protocol for the trial requires only a minimum of two months of follow-up with participants to ensure long-term safety. Kavanagh said in his article that an FDA-approved vaccine would require an average of 30 months each for its two final phases.

While a two-month follow-up will capture the vast majority of complications from the vaccine, later complications can occur. He noted the suggestion of Dr. Marcus Schabackler, CEO of ECRI, who said a trial should last at least six months and get data from every patient who receives the vaccine.

In his article, Kavanagh pointed out that many who provided public comment on the vaccine-evaluation plan said  the two-month follow-up period was too short and that 3,000 study participants were too few to detect adverse reactions among racial minorities, pregnant women and other high-risk groups. He said surveillance programs will be available for patients, and they will be important for gathering long-term information about the safety and efficacy of the vaccine. 

Kavanagh said the health officials also voiced concerns about the vaccine's effectiveness. The minimum acceptable vaccine efficacy was set at 50 percent, so this may result in a "very minimally effective vaccine," Kavanagh said.

Other concerns included the view that the number of "severe" patients required in the control group was too few; that the criteria for being a severe patient was set too low; that minority populations may be under-represented in the vaccine trials; and the fact that the vaccine is only required to prevent covid-19, with no requirements that it also prevent hospitalizations, disability or death. 

"There's concerns that this vaccine may not give lasting immunity because it's only going to be followed for two months, and it may not be totally effective because the bar is very low, 50 percent improvement in prevention of covid, which could just be preventing a cough," Kavanagh said. "You could still get covid-19. So even if you get the vaccine, you still need to wear a mask and you still need to social distance."

That could be a big pitfall. Kavanagh said if "everybody stops wearing masks and socially distancing, you may actually have an increase in covid-19 cases. So the key is you still need to follow public-health advice" and pay attention to the continued monitoring to know if you are protected long-term or not. 

And there's a chance that the coronavirus will mutate so much, like flu viruses, that new versions of the vaccine will be needed, perhaps for the foreseeable future.

"One of the greatest fears that I have is that the virus will either mutate or that your immunity will rapidly decrease," Kavanagh said. "It's fine to do the vaccine. It will help us get through this pandemic, but it is unlikely to do it by itself. We need to follow public-health measures."  

Kavanagh's article also voiced concerns about public acceptance of a vaccine, noting that a recent Harris Poll found that 80% of the respondents worried about how safe the vaccine would be if it was quickly approved, and only 58% said they would get the vaccine as soon as it was available. 

Kavanagh concluded his article: "The overall cost for society is far too high for a flawed and relaxed vaccine approval process. If the vaccine has low effectivity and primarily prevents mild disease, it will offer little protection to society and may cause inconceivable harm. To paraphrase Peter Luri, MD, MPH, from the Center for Science in Public Interest: The benefits of a minimally effective vaccine can be negated if the public relaxes wearing masks and social distancing. But even worse, if the vaccine is ineffective, it will further fuel the antivaccine movement for decades to come." 

All that said, Kavanagh said if you are at high risk for covid-19 or a frontline worker, it may be in your best interests to get the vaccine, after weighing the risks and benefits. As for the rest of the population, the months-long wait for universal distribution will give time for more research, he said: "By that time, there'll be a lot more safety data, and data on the vaccine's effectiveness."