CHICAGO (Reuters) — A study of Moderna Inc’s COVID-19 vaccine in mice lends some assurance that it will not increase the risk of more severe disease, and that one dose may provide protection against the novel coronavirus, according to preliminary data released on Friday, June 12.
Prior studies on a vaccine for SARS — a close cousin to the new virus that causes COVID-19 — suggests vaccines against this type of virus might have the unintended effect of causing more severe disease when the vaccinated person is later exposed to the pathogen, especially in individuals who do not produce an adequately strong immune response.
Scientists have seen this risk as a key hurdle that must be cleared before vaccines can be safely tested in thousands of healthy people.
While the data released by the US National Institutes of Allergy and Infectious Disease (NIAID) and Moderna was encouraging, mouse data is no guarantee of what will happen in humans.
The vaccine is currently in midstage testing in healthy volunteers. Moderna said on June 11 it plans to begin final-stage trials enrolling 30,000 people in July.
In the new study, six-week-old mice received one or two shots of a variety of doses of Moderna’s vaccine, including doses considered not strong enough to elicit a protective immune response. Researchers then exposed the mice to the virus.