Jennifer Haller receives the first administration of an mRNA vaccine, made by the biotech firm Moderna, against the pandemic coronavirus.
PHOTO: AP PHOTO/TED S. WARREN
Many viruses, including HIV and hepatitis C, have thwarted vaccine developers. But the new enemy, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), doesn't appear to be a particularly formidable target. It changes slowly, which means it's not very good at dodging the immune system, and vaccines against the related coronaviruses that cause SARS and Middle East respiratory syndrome (MERS) have worked in animal models. Corey heads the United States's HIV Vaccine Trials Network, which has seen one candidate vaccine after another crash and burn, but he is optimistic about a SARS-CoV-2 vaccine. “I don't think this is going to be that tough.”
One concern is whether people develop durable immunity to SARS-CoV-2, which is crucial given that vaccines try to mimic a natural infection. Infections with the four human coronaviruses that typically cause minor colds don't trigger long-lasting immunity. Then again, researchers have found long-lasting immune responses to the viruses causing SARS and MERS, and genetically they are far more like SARS-CoV-2. And unlike cold-causing viruses, which stay in the nose and throat, the new coronavirus targets the lower respiratory tract, where the immune response can be stronger, says Mark Slifka, an immunologist who studies vaccines at the Oregon National Primate Research Center. “When you get an infection in the lungs, you actually get high levels of antibodies and other immune cells from your bloodstream into that space.”
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