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AstraZeneca began a Phase 3 U.S. human trial of its COVID-19 vaccine on Tuesday, hoping to enroll up to 30,000 people to test its shot, developed with Britain’s Oxford University. This will be the third final-stage trial of a COVID-19 vaccine in the U.S. The U.K. is already in the midst of its AstraZeneca-Oxford Phase 3 trial, and preliminary results could be released as early as October. The U.S. trial’s launch had been postponed for a couple of days for reasons researchers could not explain, Bloomberg reports. An article in the Palm Beach Post had speculated that U.S. regulators were pressured into delaying the trial so as to pave the way for emergency use authorization before the U.S. presidential election. William Hartman, a University of Wisconsin investigator helping to lead the trial, and AstraZeneca CEO Pascal Soriot both emphasized that the research will be conducted carefully, rigorously, and free of political pressure. [Bloomberg, Palm Beach Post]

Researchers have officially confirmed a U.S. case of coronavirus reinfection. A 25-year-old Reno, Nevada, man tested positive for COVID-19 back in April after showing mild symptoms. He tested positive for the virus again in May and developed more severe symptoms as a result of a second, separate infection, according to a study released Friday that has yet to be peer reviewed. The University of Nevada, Reno School of Medicine and the Nevada State Public Health Laboratory confirmed it wasn’t just the first infection re-emerging in this case because the second virus had a different genetic strain than the first. The reinfection will have big implications for coronavirus vaccine developers worldwide. Promising vaccines have so far produced COVID-19 antibodies in human trials, but cases of reinfection suggest the antibodies gained from catching COVID-19 don’t necessarily guarantee immunity or even lessen the virus’ symptoms the second time around. [The Lancet]

Researchers at the University of Arizona said it stopped a potential coronavirus outbreak before it started by conducting regular tests of sewage from 20 buildings across campus. Subsequently, two students — both asymptomatic — were found to be infected. Wastewater testing is reportedly sensitive enough to detect the virus up to a week before an individual develops symptoms, which means there’s a better chance of locating a case before a person can spread the virus widely. “So, you have seven precious days in which you can undergo intervention,” said Ian Pepper, an environmental microbiologist who is leading the effort. University of Arizona scientists have also been analyzing samples from wastewater treatment plants across the country, researchers launched a countrywide program in the United Kingdom, and scientists in Israel have hailed it as an effective, non-invasive tracking method. [NBC News]

A study published in Nature concludes that men produce a weaker COVID-19 immune response than women do. The researchers examined the immune responses of men and women who were hospitalized with COVID-19, and discovered the women “produced more so-called T cells, which can kill virus-infected cells and stop the infection from spreading,” The New York Times reports. Men were found to have weaker T cell activation, especially the older they were. “If you look at the ones that really failed to make T cells, they were the ones who did worse with disease,” Dr. Akiko Iwasaki told the Times. However, “women who are older — even very old, like 90 years old — these women are still making pretty good, decent immune response,” Iwasaki explained. Based on these findings, Dr. Marcus Altfeld told the Times that “you could imagine scenarios where a single shot of a vaccine might be sufficient in young individuals or maybe young women, while older men might need to have three shots of vaccine.” [The New York Times]

The Food and Drug Administration has granted Abbott Laboratories emergency-use authorization for its quick, inexpensive COVID-19 antigen test. The test, called the BinaxNOW COVID-19 Ag Card, is about the size of a credit card, will cost $5, and returns results in about 15 minutes. It works kind of like a pregnancy test but still involves a nasal swab and needs to be administered by medical professionals, typically in a doctor’s office or by a school nurse. It won’t be sold directly to consumers for home use. Similar antigen tests are processed in boxlike machines and cost anywhere from $15 to $50, The Wall Street Journal reports. The newly approved antigen test has been shown to accurately detect positive cases about 97 percent of the time. It should help meet a growing demand for cheap, less-accurate COVID-19 tests that some public health officials argue the U.S. needs to return to school and work. Abbott plans to ship tens of millions of the tests in September. [The Wall Street Journal]

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