In Virginia, nearly 66 percent of adults are fully vaccinated, according to federal data, and the state has seen its daily average of coronavirus cases increase from a low of 129 on June 20 to 1,279 on Wednesday, according to a New York Times database.
“The arrival of the Delta variant, combined with the number of people who are not vaccinated, is driving our case counts back up,” Mr. Northam said at a news conference.
“The way that we’re going to win this war is to roll up our sleeve and get vaccinated,” he added.
Mr. Northam called for companies and local governments in Virginia to institute vaccine mandates of their own, and said he supported other mitigation measures, like masking, but that he was more focused on getting his state vaccinated than imposing a statewide mask mandate.
That approach is similar to that of Mayor Bill de Blasio of New York City, who called this week for proof of at least one vaccination before people can participate in indoor activities, like going inside a restaurant, gym or theater. He has strongly recommended that people wear masks indoors, but he has so far opted not to impose a mask mandate.
The Centers for Disease Control and Prevention last week recommended that even vaccinated people wear masks indoors in virus hot spots.
Mr. Northam said he had witnessed the ravages of fatal illness firsthand while working as a doctor.
“I have watched individuals fight for every breath, and I have also watched individuals take their last breath,” Mr. Northam said. “And so I want you to know that as your governor I will do everything that I can to keep you from that scenario.”