Oral antiviral pills from Merck & Co and Pfizer Inc/BioNTech SE have been shown to significantly blunt the worst outcomes of Covid-19 if taken early enough, but doctors warn vaccine-hesitant people not to confuse the benefit of the treatments with prevention afforded by vaccines.

While 72 percent of American adults have gotten a first shot of the vaccine, according to a Kaiser Family Foundation poll, the pace of vaccination has slowed, as political partisanship in the United States divides views on the value and safety of vaccines against the coronavirus.

Vaccine mandates by employers, states and the administration of US President Joe Biden have helped increase vaccinations but also fueled that controversy.

Some disease experts fear...