Moderna and Pfizer have given a boost to the idea that Americans should get another dose of coronavirus vaccines.
Pfizer is seeking federal approval for another dose for patients 65 and older and Moderna is calling for another shot for all adults, notably those who already have gotten three inoculations of its vaccine.
The drug makers say their vaccines wane in potency to protect people over time. They have, at the same time, proven to be remarkably safe and effective in keeping giant numbers of patients around the globe from getting sick, falling so ill they must be hospitalized, or even from dying of the coronavirus and its prevalent variants.