The second dose of vaccines (except J&J) is still needed for fullest protection

You got your first dose of the Covid vaccine. Now what? If your Covid-19 vaccine requires two doses, not much should change after you get your first shot, experts say. NBC News

Last Saturday, the U.S. hit a new high for the number of daily vaccinations: 4 million. The record day came as vaccinations have steadily risen over recent weeks, bringing the daily average to more than 3 million.

That means more and more people each day in the U.S. are receiving one dose of a Covid-19 vaccine. For the majority, who will receive either the Pfizer-BioNTech or Moderna vaccine, it’s just the first dose; in three to four weeks, they’ll be returning for a second.

But is a person protected after just the first shot?

Only if the vaccine was the Johnson & Johnson one-dose shot. For the other two vaccines currently available in the U.S., experts say it’s essential that people who receive a two-dose vaccine come back for the second in order to be fully protected.

People who are partially vaccinated shouldn’t change their behavior and instead should sit tight until they have completed their vaccination series, said Dr. Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia and a member of the Food and Drug Administration's vaccine advisory committee.

“It just frightens me that we have, in any sense, put out there the notion that [Pfizer and Moderna] are anything other than a two-dose vaccine,” Offit said.

Last week, the Centers for Disease Control and Prevention reported that the first dose of either the Pfizer or Moderna vaccine was 80 percent effective at preventing infection. That protection was measured two weeks after the first dose, but before the second.

During a White House Covid-19 response team briefing Monday, Dr. Anthony Fauci, the nation’s leading infectious disease expert, qualified those findings, saying, “It is somewhat of a tenuous 80 percent.”

“The question,” Fauci said, “is how long does [that protection] last?”

“The best reason to wait for that second dose is you want to get durable immunity,” Offit said.

Research from Pfizer, released last week, showed that protection lasted at least six months in people who received both doses of the vaccine.

“Getting the second dose is going to be really important for lasting protection,” said Dr. Peter Hotez, co-director of the Center for Vaccine Development at Texas Children’s Hospital and dean of the National School of Tropical Medicine at Baylor College of Medicine. ...