Jan 28, 2021 10:52am One infectious disease specialist said efforts to determine if existing vaccines will work against new COVID strains have left us "in a state of ignorance" due to incomplete data.(Bill Oxford/Getty Images) Just as the U.S. government is starting to ramp up purchases of Pfizer’s and Moderna’s mRNA vaccines to prevent COVID-19, a troubling question is emerging in the scientific community: Can these shots protect people against aggressive new variants racing through the U.K., South Africa and Brazil? Several analysts have scoured the medical literature and interviewed infectious disease experts in an effort to answer that question. Their conclusion? There is no clear answer. At least not yet.