A Mayo Clinic Health System team examined more than 31,000 people in four states who had received at least one dose of either vaccine – and found that their vaccines were over 80% effective for prevent infection 36 days after the first dose.
The vaccine’s effectiveness was 75% 15 days after the first dose and appeared to be 89% effective from 36 days after the second dose, according to research, which has not yet been reviewed by pairs.
More than 59 million doses of the vaccine have so far been administered in the United States, according to data from the United States Centers for Disease Control and Prevention.
But Dr Christopher Murray, director of the Institute for Health Metrics and Evaluation at the University of Washington, said on Friday that the United States is unlikely to gain herd immunity to the virus before winter.
“We know Covid is really seasonal, so when the next winter rolls around we need to have a much higher level of protection to stop Covid on its tracks than we are likely to achieve,” he said.
Collective immunity does not take effect until 80% or more of the population is immunized, either by infection or by vaccination. And the new variations can complicate the picture, Murray said. If people can be re-infected with the new variants, the pandemic can start again.
While officials hope the vaccines will be widely distributed by the end of the summer, President Biden said on Friday that issues such as weather, strain mutations and manufacturing delays made it difficult to establish ‘a calendar.
Too risky to give single doses, says Fauci
Some experts suggest that one of the ways to protect more people quickly is to prioritize the administration of the first doses of the vaccine.
“Would that really be a problem, because if we could do that we could immunize a lot more high risk people, quickly … Everyone needs a second dose, but I think we can do it? in a way that stays safe and protects a lot more people, ”Jha told CNN’s Poppy Harlow.
But Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said on Friday that a single-dose plan would be too risky.
Fauci said he was concerned that if large numbers of people received a single vaccine and had less than optimal immune responses, they could be exposed to the virus and start incubating viral mutations. In theory, new variants could emerge, he said.
“We will stick to the scientifically documented efficacy and optimal response of a premium followed by a boost with mRNA vaccines,” Fauci said at a White House briefing.
Jha, for his part, said he agreed that everyone needed a second dose, “I think the question is, at the moment we are waiting four weeks between the first and the second dose. . What if we went six weeks or eight weeks or 10 weeks – not much longer than that. “
School can reopen regardless of virus spread, CDC director says
In the hope of regaining some sense of normalcy, a priority for many families and officials has been to allow students to resume in-person learning.
And CDC director Dr Rochelle Walensky said on Friday that, given the right precautions, schools could open regardless of the spread of the virus in the community.
CNN’s analysis on Tuesday indicated that about 90% of children lived in so-called red areas under CDC leadership – meaning there is a high level of community spread of the virus. But even under these conditions, schools can safely reopen if they take precautions, Walensky said at a White House briefing.
The CDC said schools can reopen if they ensure they reduce the risk of the spread through the use of a universal mask, measures to keep children and staff six feet away from one of the other, frequent cleaning and disinfection, testing and contact tracing.
The CDC director’s assurances came as Fauci announced that the United States should have vaccine safety data for high school-age children by early fall.
The companies are just starting to test younger age groups but have tested their vaccines on young people between the ages of 12 and 17, Fauci said at a White House briefing. Safety data for young children is unlikely to be available until early next year, he said.
Reluctance to immunize is no excuse for inequalities
At the same time, the testing and distribution of vaccines has highlighted inequalities in the medical field.
People of color have been grossly under-represented in U.S. vaccine trials over the past decade, according to a new study released Friday by researchers at Fred Hutchinson Cancer Research Center, Harvard, Emory and others. institutions.
The study found that whites made up the majority, or 78%, of participants in trials conducted between June 2011 and June 2020.
The study, published in the JAMA Network Open, comes as the nation grapples with a pandemic that has had a disproportionate impact on people of color. Health leaders are working to tackle mistrust of vaccines among blacks and browns, saying the vaccine is the key to preventing their communities from becoming more devastating.
But that hesitation shouldn’t be an excuse for officials to explain racial disparities in immunization, Fauci said.
“It’s that we really have to reach out into the community to have access to minority populations that they don’t have,” Fauci said in an interview with MSNBC.
CNN’s Christopher Rios, Amanda Sealy, Lauren Mascarenhas, Kevin Liptak, Maggie Fox, Nicholas Neville and Nicquel Terry Ellis contributed to this report.