A series of studies in mice of Moderna Inc's COVID-19 lent some assurance that it may 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.
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.