After the remarkable success of the mRNA vaccines in protecting people against COVID-19, scientists are turning their attention next to another annual respiratory scourge: influenza. Both Moderna and Pfizer—makers of the first vaccines to earn U.S. Food and Drug Administration (FDA) approval using the mRNA technology—are studying whether subbing in the influenza virus’ genetic material in that platform will prove equally fruitful. On Sept. 14, Pfizer announced that the first volunteers had received doses of its mRNA flu shot; the Phase 3 study will involve more than 25,000 adults in the U.S. ages 18 and up who will be randomly...
