Fauci says he's optimistic about coronavirus vaccine protection but concerned how long it will last

The nation's leading infectious disease expert, Dr. Anthony Fauci, said he’s “cautiously optimistic” a coronavirus vaccine will provide some protection against SARS-CoV-2 and COVID-19, the illness it causes, but he is concerned about how long that protection could last.

In an interview with JAMA editor-in-chief Howard Bauchner Tuesday, the director of the National Institute of Allergy and Infectious Diseases questioned the "durability" of candidate vaccines.

“If you look at the duration of protection when you recover from one of the several benign coronaviruses that cause the common cold, the durability of infection is only measured in a year or less as opposed to the other infections where you can get 15 to 20 years of protection,” he said.

Dr. Greg Poland, director and founder of Mayo Clinic Vaccine Research Group, said natural immunity from coronaviruses SARS-CoV-1 and MERS can be detected two to three years after recovering from infection. However, immunity for seasonal coronaviruses can last as little as 80 days to several years in some people.

There are no licensed vaccines for any of these coronaviruses.

“There’s an immunologic secret locked up in the long class of coronaviruses that we don’t yet understand,” he said.

The National Institutes of Health has been working on a potential vaccine with biotech firm Moderna, which plans to enroll about 30,000 people in a phase 3 trial by July, Fauci said in the interview.

But Poland says that may not be a big enough sample size to determine the candidate vaccine’s side effects.

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“You have a shot of detecting a bad side effect will occur 1 in 10,000 times,” he said. Even that may be difficult to accomplish as it becomes harder to identify outbreaks in the summer.

Moderna gave the first doses of its vaccine candidate, called mRNA-1273, on March 16.

All participants in the Phase 1 clinical trial tests made antibodies to the virus. Known as neutralizing antibodies, when tested on human cells in the laboratory they stopped the virus from reproducing.

After participants received two doses of the candidate vaccine, their antibody levels were about the same as in people who have recovered from a COVID-19 infection. It’s presumed any vaccine created for the new coronavirus will require two doses spaced a month or two apart for full protection against the virus.

Fauci told Bauchner he hopes to have hundreds of millions of doses available by the beginning of 2021 as companies and the federal government begin to mass-manufacture and test for efficacy at the same time. He acknowledged it is a risky investment.

“We’re going to start manufacturing doses of the vaccines way before we even know that the vaccine works,” he said. “That’s what going on right now that’s very unique in vaccine development.”

But Poland argued that the rush to mass-distribute a coronavirus vaccine by early next year is not only a risky investment but could do potential harm to those who elect to take it.

“Don’t accept the unbridled enthusiasm currently happening in the field,” he said. “There are always unexpected surprises and scientific obstacles – always – that we don’t understand.”

Contributing: Elizabeth Weise, USA TODAY. Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.

This article originally appeared on USA TODAY: Coronavirus vaccine: Dr. Anthony Fauci questions long-term immunity