The coronavirus vaccine may not grant full immunity after just one dose, according to a new report.

When a vaccine proves effective, there’s a good chance it will entail a two-dose series, USA Today reported. Shots may need to be administered one month apart, with a booster following several years later.

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As of June 2, the World Health Organization (WHO) listed 10 vaccine candidates under clinical evaluation, with 123 candidates in preclinical evaluation.

Barry Bloom, immunologist and professor of public health at the Harvard T.H. Chan School of Public Health in Boston, told USA Today that almost all of the vaccine developers are considering two shots in their regimens.

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According to the outlet’s report, the first shot in the series would “prime the immune system” to help the body recognize the virus, followed by a second shot to “strengthen the immune response.”

Almost all of the vaccine developers are considering two shots in their regimens, one immunologist said. (iStock)

When vaccine candidates reach human clinical trials, more precise dosing will become clear, Dr. Kelly Moore, associate director of immunization education for the Immunization Action Coalition, told the outlet.

After the first dose of a vaccine, the immune system develops antibodies and immune cells in about 14 days, says L.J. Tan, chief strategy officer with the Immunization Action Coalition and co-chair of the National Adult Immunization Summit and National Influenza Vaccine Summit.

Tan estimated any COVID-19 vaccine requiring two doses would likely be administered about a month or two apart.

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In addition, WHO officials said the coronavirus isn’t mutating to become more dangerous during a briefing on Wednesday. Since the SARS-CoV-2 is seemingly stable so far, initial vaccines could act as boosters later on to extend immunity, Bloom told the outlet.

However, scientists aren’t sure how durable people’s immune response will be. For coronaviruses causing the common cold, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said immunity almost always lasts less than a year.

A two-dose regimen in treating COVID-19 nationwide may demand more extensive coordination and record keeping to ensure patients receive the full course of vaccination, experts say. (iStock)

"It may be completely different with this coronavirus, with SARS-CoV-2, it may be that they induce a response that’s quite durable," Fauci told the editor of the Journal of the American Medical Association.

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A two-dose regimen in treating COVID-19 across the country may demand more extensive coordination and record-keeping to ensure patients receive the full course of vaccination.

While scientists race for an effective vaccine, directors of state health agencies are reportedly using the time to prepare immunization registries. USA Today reported the agency directors are in frequent contact with the CDC and immunization registry managers to “record and track the vaccinations of large numbers of adults.”