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June 4, 2020 - When and if the world gets a coronavirus vaccine, it will probably require two vaccinations given about a month apart, health officials said.

National Institutes of Health Director Dr. Francis Collins told CNN on Thursday that a one-dose vaccine would be ideal because of the cost and also because some people wouldn’t show up for the second shot.

“There is certainly a chance that one or more of these vaccines might turn out to require two shots in order to get full immune response,” he said. “That’s one of the reasons to do the experiments and the research trials to find that out. If what it takes to provide full protection for any of these is two doses, we want to know that.”

The first shot would prime the immune system, helping it recognize the virus, and the second shot would strengthen the immune response, USA Today reported Thursday.

Barry Bloom, an immunologist and professor of public health at the Harvard T.H. Chan School of Public Health in Boston, said about 100 vaccines are in various stages of testing.

“As far as I am aware, with one set of exceptions, all the frontline vaccine developers are contemplating two shots," Bloom said. "The one exception is Merck, which last week pushed forward on two vaccines, each of which they hoped would be one-shot vaccines.”

L.J. Tan of the Immunization Action Coalition told USA Today the two doses would be given about a month apart. Scientists also said the coronavirus vaccine might require booster shots in later years.

Of the drug companies racing to develop a coronavirus vaccine, scientists with Moderna in the US and Oxford University in England have started clinical trials in humans.

Show Sources “Coronavirus vaccine might require two doses, NIH chief says.”
USA Today: "A coronavirus vaccine could require you to get two shots. Here's why."
WebMD. “Moderna Starts Phase Two of COVID-19 Vaccine Study.” “Oxford Starts Human Clinical Trials for Vaccine.”

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