Even as scientists worldwide race to develop a vaccine against COVID-19, a vaccine adviser to the government has warned that there is no guarantee the shots will prove widely effective.
“If we’re lucky, we’ll get a vaccine that’s effective at 90 percent, but if we’re less lucky, it could be 30%, and if we’re unlucky, we could get no vaccine at all,” warned Cyrille Cohen, head of the immunotherapy laboratory at Bar Ilan University. “We really don’t know,” he stressed.
Anthony Fauci, America’s top infectious disease expert, has said he would “settle” for a vaccine that is 70% to 75% effective, while the US Food and Drug Administration wants any vaccine approved for the American market to deliver at least 50% protection.
Cohen, a newly-appointed member of a Health Ministry advisory committee that deals with coronavirus vaccines, told The Times of Israel: “Like the US, Israel may consider candidate vaccines with different levels of effectiveness, so long as they abide by international regulatory standards.”
A vaccine with low effectiveness would cut down the incidence of COVID-19, but would not deliver so-called herd immunity, which health officials are aiming for in order to minimize the threat of the virus.
For herd immunity, a vaccine with around 80% effectiveness would be needed, according to Cohen, “but if you have anti-vaxxers who won’t agree to vaccinate, this would lower the efficacy of community protection.”
To overcome the possible low effectiveness of shots, Cohen thinks it is possible that doctors would end up double-barreling them, and giving the first vaccine available when it is ready, followed by another, different vaccine when it becomes available.
He believes this underscores the importance of Israel’s own efforts to make a vaccine — including a recent breakthrough at the Israel Institute for Biological Research — even as the country has signed a deal to buy a vaccine that is being developed by the American biotech company Moderna.
“One scenario is we will get the Moderna vaccine and then get the Biological Institute vaccine,” he said, noting that there are already precedents, such as polio, for giving two vaccines for the same disease.
Another Israeli expert, Prof. Yehuda Carmeli, told The Times of Israel last month that while a vaccine would likely be available in a year, “vaccines are usually much less efficacious in the older population and in immunocompromised patients — and those are the people who actually most need the protection.” Added Carmeli, the head of Israel’s National Institute for Antibiotic Resistance and Infection Control, “I don’t think we’ll be able to vaccinate enough of the population to get herd immunity just by the vaccine.”
Vaccine trials are underway in various countries, but Cohen said Monday there are still many unknown factors.
“We don’t know much about the long-term behavior of the virus,” he said, adding that as vaccines function by inducing immune responses in the body, there are added uncertainties regarding how long this will prove effective against the coronavirus.
“People need to understand that to know the extent of the protective nature of a vaccine, you need to use it on a large scale, the scale of a population, for a long period,” he said.
Some infectious diseases experts are more confident than Cohen. Shlomo L. Maayan, head the infectious disease division at Barzilai Medical Center in Ashkelon, told The Times of Israel that a vaccine’s effectiveness should “ideally be 85% to 90%,” which he said was a realistic prospect.
“If a vaccine is 40% effective I don’t think it will get to the market at all,” he said.