CDC estimates more than a million people have received unauthorized booster shots, AstraZeneca will seek FDA approval later this year, and more in this week's roundup of Covid-19 news.

• HHS on Thursday announced it is requiring more than 25,000 health care workers to be vaccinated against Covid-19. Health care workers and research staff at the Indian Health Service, National Institutes of Health, and the U.S. Public Health Service Commissioned Corps will be required to get vaccinated. "Our number one goal is the health and safety of the American public, including our federal workforce, and vaccines are the best tool we have to protect people from Covid-19, prevent the spread of the Delta variant, and save lives," Xavier Becerra, HHS secretary, said. (Doherty, Axios, 8/12)

• The Department of Veteran Affairs (VA) on Thursday expanded its Covid-19 vaccine mandate to include an additional 245,000 workers, volunteers, and contractors within its health care system. The VA's initial mandate, which was announced last month, covered 115,000 frontline health care workers. Roughly 63% of the VA's 351,000 are currently vaccinated, the New York Times reports. (Steinhauer, New York Times, 8/12)

• The Supreme Court on Thursday declined to block Indiana University's Covid-19 vaccine mandate for students, faculty, and staff. Justice Amy Coney Barrett denied a motion for emergency relief from students challenging the university's mandate without comment. According to the New York Times, the justice did not refer the application to the full court or ask the university for a response—indicating that the application did not have solid legal grounds. (Liptak, New York Times, 8/12)

• CDC on Wednesday recommended pregnant and breastfeeding individuals be vaccinated against Covid-19. In issuing the recommendation, the agency cited new research indicating vaccinations do not lead to an increased risk of miscarriage, as well as additional research showing that Covid-19 significantly increases the risks of pregnancy complications, such as preterm birth. CDC Director Rochelle Walensky said, "CDC encourages all pregnant people or people who are thinking about becoming pregnant and those breastfeeding to get vaccinated to protect themselves from Covid-19 … The vaccines are safe and effective, and it has never been more urgent to increase vaccinations." According to CDC data, only 23% of pregnant women have received at least one dose of a Covid-19 vaccine, and Kaiser Health News reports that physicians are reporting a rise in the number of unvaccinated pregnant people being hospitalized with severe cases of Covid-19. According to the New York Times, pregnant patients—when compared with non-pregnant patients—have a 70% increased risk of dying from Covid-19, and are more likely to require intensive care, a heart-lung bypass machine, and ventilators. Sascha Ellington, an epidemiologist leading CDC's emergency preparedness response team in the division of reproductive health, said, "At this time, the benefits of vaccination, and the known risks of Covid during pregnancy and the high rates of transmission right now outweigh any theoretical risks of the vaccine." (Rabin, New York Times, 8/11; Bernstein/Shammas, Washington Post, 8/11; Axios, 8/11; Lopez, Kaiser Health News, 8/12)

• Tedros Adhanom Ghebreyesus, director general of the World Health Organization (WHO), on Wednesday said unless things change, the world could see another 100 million coronavirus cases by early 2022. "At the current trajectory, we could pass 300 million cases early next year," he said. "But we can change that. We are all in this together, but the world is not acting like it." During a media briefing, WHO officials also addressed how more transmissible variants, such as the delta variant, would affect herd immunity. Katherine O'Brien, head of WHO's immunization department, said, "What's been happening with coronavirus … is that as variants are emerging and are more transmissible, it does mean that a higher fraction of people need to be vaccinated to likely achieve some level of herd immunity." (Reyes/Miller, Axios, 8/11; Weixel, The Hill, 8/11)

• A new preprint study in medRxiv found that high antibody levels correlated with increased protection against Covid-19. The Coronavirus Efficacy (COVE) study, which took place between July and October 2020, included 30,415 participants, half of whom received two doses of the Moderna vaccine, and half who received a placebo. Of the participants who received vaccines, 1,051 had their neutralizing antibodies and binding antibodies measured twice, once after their second shot and then a month later. Overall, the researchers found that participants with more antibodies were less likely to get Covid-19, with the effect lasting at least four months after the second vaccine dose. According to the researchers, these findings suggest that measuring antibody levels against Covid-19 protection could be used by scientists to develop new vaccines and boosters without the need for large clinical trials. In fact, such "correlates to protection" have been used to develop vaccines for other diseases, such as influenza, USA Today reports. "The hope is that [FDA] will see these data and use them as a provisional approval mechanism," Peter Gilbert, a biostatistician at the Fred Hutchinson Cancer Research Center and one of the study's co-authors, said. (Weise, USA Today, 8/10)

• An internal CDC document estimates that 1.1 million people who received the Pfizer-BioNTech or Moderna vaccines have received an unauthorized third dose. According to ABC News, the number is likely an underestimate, since it does not include people who may have received an additional dose after first receiving Johnson & Johnson (J&J)'s one-dose vaccine. According to the document, Florida, Ohio, California, and Illinois, and Tennessee have reported the highest number of people getting third vaccine doses. (Flaherty/Strauss, ABC News, 8/12)

• J&J's Covid-19 vaccine is effective at preventing hospitalization and death in patients infected with the delta variant, according to preliminary data from a large-scale clinical trial in South Africa. The trial involved about 480,000 health care workers in the country who were vaccinated between February and May of this year. According to Glenda Gray, president of the South African Medical Research Council and the trial's co-leader, J&J's vaccine was 71% effective against hospitalization and 96% effective against death from the delta variant. (Prieb, The Hill, 8/6; Foley, Politico, 8/6)

• AstraZeneca last month announced it would seek full approval from FDA for its Covid-19 vaccine in the second half of this year. Although more than 170 countries have authorized AstraZeneca's vaccine for use, the United States has not. The company originally intended to seek emergency use authorization from FDA in April, but then decided to seek full approval instead, The Hill reports. Although AstraZeneca CEO Pascal Soroit acknowledged that the United States currently has several vaccine options, he said the company has "a good vaccine, and we just want to make sure it's ready to be used if needed." (Vakil, The Hill, 7/29)