June 22, 2020 / 6:21 PM / 17 days ago

Diabetes drug may lower COVID-19 death risk in women; key immune cells fail to respond to virus

(Reuters) - The following is a brief roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for COVID-19, the illness caused by the virus.

FILE PHOTO: The ultrastructural morphology exhibited by the 2019 Novel Coronavirus (2019-nCoV), which was identified as the cause of an outbreak of respiratory illness first detected in Wuhan, China, is seen in an illustration released by the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, U.S. January 29, 2020. Alissa Eckert, MS; Dan Higgins, MAM/CDC/Handout via REUTERS/File Photo

Metformin tied to lower risk of COVID-19 death in women

Women taking the widely used oral diabetes medication metformin may be at lower risk for fatal COVID-19, according to a study posted on Saturday that has not yet been peer-reviewed. Among more than 6,200 adults with diabetes or obesity and commercial insurance who were hospitalized with COVID-19, there were fewer deaths among women who had filled their 90-day metformin prescriptions than among those not taking the medicine. After adjusting for other risk factors, they were roughly 21% to 24% less likely to die of the disease. The link was not seen in men. "We know that metformin has different effects between men and women. In the diabetes prevention trial, metformin reduced CRP (the inflammation marker C-reactive protein) twice as much in women as men," study coauthor Carolyn Bramante of the University of Minnesota told Reuters. Metformin also decreases levels of TNF-alpha, an inflammation protein that appears to make COVID-19 worse, she said. Studies have suggested metformin may bring down TNF-alpha levels to a greater extent in women than in men, she added. "The fact that we saw the benefit in women only, and the fact that metformin lowers TNF-alpha in female mice, might suggest that the TNF-alpha effects of metformin are why it helps in COVID-19," Bramante said. Formal clinical trials are needed to confirm the theories raised by this observational study. Metformin is a safe, cheap and widely available medicine, making it "a very realistic treatment" if proven in larger trials, she added. (bit.ly/317D2yi)

Crucial immune cells failing to respond to virus

An important set of immune cells is failing to respond properly to the novel coronavirus, providing a possible explanation for why some patients appear mildly ill at first and suddenly deteriorate, according to new research from Hong Kong. The dendritic cells are supposed to alert the immune system to the presence of virus or bacteria, so that other immune cells, called macrophages, can attack and "kill" the invaders. While infected macrophages respond properly to the virus, infected dendritic cells fail to send out their usual alarms in the form of proteins called interferons, researchers reported on Sunday in the Journal of Infectious Diseases. Furthermore, in dendritic cells the virus inhibits a crucial protein called STAT1, which activates interferons and other important substances, they report. Coauthors Kwok-Yung Yuen and Jasper Fuk-Woo Chan of the University of Hong Kong told Reuters in a joint email that these dendritic cell dysfunctions may contribute to symptoms in some patients. (bit.ly/2YnCd2x)

Ceramic used in spine implants inactivates coronavirus

Silicon nitride, a ceramic often used in spinal implants because it kills bacteria by releasing disinfectant chemicals from its surface, can also inactivate the new coronavirus, according to a new study. In laboratory experiments, researchers in Japan exposed coronavirus particles to silicon nitride, aluminum nitride, and copper particles. All three materials showed greater than 99% viral inactivation after one minute, but silicone nitride is the safest of the three. Virus treated by the other two substances could still damage cells in other ways, the researchers reported on Saturday in a not-yet-peer-reviewed paper. "Further studies are needed to validate these findings and investigate whether silicon nitride can be incorporated into personal protective equipment and commonly touched surfaces, as a strategy to discourage viral persistence and disease spread," the researchers said. Shares of ceramics company SiNtx Technologies Inc, which makes the silicon nitride powder, jumped 170% on the report. (bit.ly/2YlscCO)

Antibody levels in recovered COVID-19 patients decline quickly

Antibody levels in recovered COVID-19 patients fell sharply within a few months after infection, according to a Chinese study of 37 symptomatic and 37 asymptomatic individuals, raising questions about the length of immunity an infection may confer against the novel coronavirus. Over 90% of those who initially had IgG antibodies - one of the main types of antibody induced after infection - showed sharp declines in 2 to 3 months. The research, published in Nature Medicine, highlights the risks of using COVID-19 "immunity passports" and supports the prolonged use of public health interventions such as social distancing and isolating high-risk groups, researchers said. (reut.rs/2BsFjZZ; go.nature.com/2NkCay6)

New storage solution may allow safer collection, transport of coronavirus test swabs

Researchers in Brazil have developed a way to make handling infected test swab samples from COVID-19 patients less risky for healthcare workers. In every sample-collection kit, they include a storage solution that inactivates the infectious parts of virus without affecting the integrity of the viral RNA that diagnostic tests look for. The solution is made of a salt buffer with guanidine, explained Flávio Guimarães da Fonseca of Federal University of Minas Gerais in Belo Horizonte. "Guanidine is a denaturing chemical that destroys proteins. Therefore the protein components of the virus are degraded (killing the virus) while the virus genetic material is preserved for up to 16 days, even at room temperature," he told Reuters. "This is a particularly important feature in developing countries with limitations in diagnostic laboratory availability, as well as difficult logistics to take samples to the labs." The treated virus fails to grow on cultured cells, he said, adding that many laboratories in Belo Horizonte are already using the solution. One limitation of the work, he notes, is that researchers did not compare their results to those of labs working with a regular, non-denaturing sampling solution. The report, posted on Saturday on medRxiv, has not yet been peer-reviewed. (bit.ly/3epMdh9)

Reporting by Nancy Lapid, Roxanne Liu and Se Young Lee; Editing by Bill Berkrot

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