Novavax has filed for regulatory approval of its Covid-19 vaccine in the United Kingdom; an estimated 115,000 health care workers have died during the pandemic; and more in this week's roundup of Covid-19 news.

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• A study published in CDC's Morbidity and Mortality Weekly Report found people who were vaccinated against Covid-19 were less likely to die of non-Covid causes compared with those who were unvaccinated, MedPage Today reports. For the study, researchers examined data from 11 million people who were enrolled in seven sites of CDC's Vaccine Safety Datalink between December 2020 and July 2021. Of the participants, 6.4 million were vaccinated, and 4.6 million were unvaccinated. Notably, researchers selected the unvaccinated group from individuals who had received a flu vaccine in the last two years "to ensure comparably health-seeking behavior." After excluding deaths related to Covid-19, the researchers found the standardized mortality rates (SMR) for Pfizer-BioNTech and Moderna vaccine recipients to be 0.35 and 0.34 per 100 person-years, respectively. In comparison, the unvaccinated mRNA vaccine comparison group had an SMR of 1.11 per 100 person-years. Similarly, recipients of Johnson & Johnson's (J&J) vaccine had a lower SMR (0.84 per 100 person years) compared with the group's unvaccinated comparison recipients (1.47 per 100 person years). According to the researchers, "The lower mortality risk after Covid-19 vaccination suggests substantial healthy vaccine effects ... which will be explored in future analyses." (Walker, MedPage Today, 10/22)

• According to updated clinical guidance from CDC, "moderately or severely immunocompromised" adults who received a third dose of an mRNA Covid-19 can receive a fourth dose of any Covid-19 vaccine at least six months after their third dose. CDC initially recommended third doses of Pfizer-BioNTech's and Moderna's Covid-19 vaccine for immunocompromised people in August. CDC also recommends moderately and severely immunocompromised individuals who initially received J&J's Covid-19 vaccine receive an additional dose of any Covid-19 vaccine at least two months after their initial dose. However, immunocompromised J&J recipients "should not receive more than two Covid-19 vaccine doses," CDC said. (Slotnik, New York Times, 10/27; Christensen, CNN, 10/26; Walker, MedPage Today, 10/27)

• The World Health Organization (WHO) estimates that around 115,000 health care workers died from Covid-19 between January 2020 and May 2021, STAT News reports. According to WHO Director-General Tedros Adhanom Ghebreyesus, two-in-five health care workers are fully vaccinated, but "that average masks huge differences across regions and economic groupings." For example, more than 80% of health care workers in wealthy countries are fully vaccinated, but in Africa, the rate is less than 10%. "The backbone of every health system is its workforce—the people who deliver the services on which we rely at some point in our lives," Tedros said. "More than 10 months since the first vaccines were approved, the fact that millions of health care workers still haven't been vaccinated is an indictment on the countries and companies that control the global supply of vaccines." (Joseph, STAT News, 10/21)

• Merck on Wednesday announced it granted a royalty-free license of its experimental antiviral Covid-19 drug, molnupiravir, to the Medicines Patent Pool, a United Nations-backed nonprofit that works to make medical treatment and technologies accessible worldwide. Under this license, companies in 105 low- and middle-income nations, primarily in Asia and Africa, will be allowed to produce the drug after it is granted regulatory approval. "From the beginning we knew we wanted to expand the geographic footprint of our generic partners," said Paul Schaper, Merck's executive director of global pharmaceutical public policy. He added that the company's licensing deals and supply agreements will provide "global access in high-income and low- and middle-income countries at the same time." (Knutson, Axios, 10/27; Nolen, New York Times, 10/27; Hopkins/McKay, Wall Street Journal, 10/27)

• A study published in Science Translational Medicine found that pregnant and breastfeeding women may have a slower immune response after the first dose of a Covid-19 vaccine than other women, the New York Times reports. For the study, researchers analyzed antibodies from 84 pregnant women, 31 breastfeeding women, and 16 nonpregnant women who had been vaccinated with either Pfizer-BioNTech's or Moderna's Covid-19 vaccines. The researchers found that after a first vaccine dose, pregnant and breastfeeding women had fewer antibodies and a less effective immune response than other women of the same age. However, the differences in antibody levels and immune responses largely declined after a second vaccine dose. According to the Times, the study's findings emphasize the importance of a second vaccine dose for pregnant and breastfeeding women since they may remain vulnerable to the coronavirus after an initial dose. (Mandavilli, New York Times, 10/27)

• Novavax announced on Wednesday that it has filed for regulatory approval of its Covid-19 vaccine in the United Kingdom, the Washington Business Journal (WBJ) reports. A phase 3 clinical trial of 15,000 participants in the U.K. found the vaccine had an overall efficacy rate of 89.7% against the coronavirus, including variants. Similarly, another trial of 30,000 people in the United States and Mexico demonstrated 100% protection against moderate and severe Covid-19 and an overall efficacy rate of 90.4%. Novavax president and CEO Stanley Erck said the company "will be prepared to deliver vaccine doses following what we anticipate will be a positive decision" from the U.K. regulatory agency. According to WBJ, Novavax also plans to seek regulatory approval in other countries, including the United States, Canada, India, and Indonesia. (Gilgore, Washington Business Journal, 10/27)