The White House Chief Medical Advisor Dr. Anthony Fauci said Monday that Americans should continue to receive two doses of the Pfizer and Moderna Covid-19 vaccines despite a recent study which showed the shots are highly effective after just one dose. A study published last week found that a single dose of Moderna's or Pfizer's Covid 19 vaccine was 80% effective in preventing coronavirus infections among health care personnel and other workers. Two doses are better than one, the federal health officials said, adding that the effectiveness of the vaccines was increased to 90% two weeks after the second dose. While the 80% figure was great news, Fauci said Monday that he is still concerned about the length of protection after a single dose, particularly with the emergence of highly contagious variants that have shown the ability to evade the protection of vaccines.
When you look at the level of protection after a dose, you can say it is 80% but it is somewhat of a fragile 80%, says Fauci during a White House news briefing on the pandemic. When you take it at once, the question is how long does it last? Highly infectious Covid-19 variants that have shown some resistance to vaccines also pose a challenge, said Fauci. If you do n't have the full effect of two doses, he said, you are in a tenuous zone. Fauci's comments come as some health experts and public health officials argue that the U.S. should prioritize introducing only one dose of the vaccines before moving on to second doses, accelerating the speed of vaccinations across the nation.
Unlike Johnson Johnson's vaccine, which requires one dose, Pfizer and Moderna's vaccines require two shots taken three to four weeks apart. In the UK, health officials decided to stretch the time between the first and second doses to 12 weeks in an effort to speed up vaccinations. Fauci has said repeatedly over the last few months that the United States should stick to the two-dose regimen. Paul Offit, a voting member of the FDA Vaccines and Related Biological Products Advisory Committee who reviewed both Moderna's and Pfizer's vaccine for emergency use authorization, told CNBC last week that studies have shown immunity appears to be longer after the second dose, meaning protection may last longer. The two dose vaccine regimen also produces 10 times the amount of neutralizing antibodies, which play an important role in fighting the virus, from the first to second dose, Offit told CNBC. Scientists also detected so-called T cells after the second dose, another important part of the immune response that usually provides longer-lasting immunity, he said. Fauci said Monday that he respects arguments for a one-dose strategy, but added that the United States currently has enough doses to provide first and second doses for Americans. Although we always have an open mind, we consider the route we 're on to be the best, he said.