(Reuters) – The following is a summary of some of the latest scientific studies on the new coronavirus and efforts to find treatments and vaccines against COVID-19, the disease caused by the virus.
MRNA vaccines stimulate lymph nodes for long-term protection
A new study confirms, along with the induction of antibodies for immediate defense, mRNA vaccines against COVID-19 also stimulate lymph nodes to generate immune cells that provide long-term protection. The early wave of antibodies is generated by B cells called plasmablasts. In healthy volunteers, blood tests showed that two doses of the Pfizer / BioNTech vaccine induced “a strong plasmablast response,” said co-author Ali Ellebedy of the University of Washington School of Medicine in St. Louis. Louis. Immune cells that will produce antibodies after exposure to the virus in the coming years (called memory B cells) are generated by germ cell B cells that are only found in the lymph nodes near the sites of injection of the vaccine, according to his team in a document that is currently under peer review. possible publication in a journal Nature. In repeated volunteer lymph node biopsies, “we saw a robust germinal response,” Ellebedy said. The responses lasted at least seven weeks, “with no sign of cooling soon,” he added. “Although we do not yet have long-term samples, it is safe to assume given the magnitude and persistence of the germline reaction that these individuals will develop a lasting immune response” to mRNA vaccines. The Modern Vaccine Inc. also uses mRNA technology. (bit.ly/3tnAiYw)
The accuracy of the throat swab test can vary depending on the time of day
The accuracy of standard PCR testing of nasopharyngeal swab samples may vary depending on the time of day, new data suggest. The researchers analyzed 31,094 tests performed on symptomatic and asymptomatic individuals at 127 test sites, including 2,438 tests that showed COVID-19. In a paper published Saturday in medRxiv prior to the peer review, they report that the tests were probably positive around 2 p.m., and the proportion of positive tests in the early afternoon was twice as high as the lowest proportion observed in other times of the day. The study “suggests that people may be more contagious at certain times of the day and raises questions about whether SARS-CoV-2 tests may be less accurate when collected between the afternoon and morning,” the co-author said. Dr. Candace McNaughton. of Vanderbilt University. “If our findings are confirmed, doctors and public health teams could focus their efforts on reducing the risk of viral spread during times of maximum viral outbreak,” he said. This could involve emphasizing half-day masking in the early afternoon at home while isolated or encouraging early-morning shopping for vulnerable populations. “There may be a greater benefit in repeating tests if a negative test was collected when the viral spill is generally lower,” McNaughton said. (bit.ly/2NjcZiY)
Delayed surgery after COVID-19 is recommended
Whenever possible, surgery should be delayed for at least seven weeks after infection with the new coronavirus, and patients who are still showing symptoms at this time may benefit from a new delay, according to researchers on Anesthesia. They reviewed data on 140,231 surgery patients from 116 countries, including 3,127 with a history of COVID-19. The mortality rate at 30 days after surgery was 1.4% in patients who never had COVID-19. It was 9.1% among patients diagnosed in the two weeks prior to surgery, 6.9% among those diagnosed within 3 to 4 weeks, and 5.5% when diagnosed with 5 to 4 weeks. at 6 weeks preoperatively. The mortality rate was reduced to 2% when at least 7 weeks elapsed between diagnosis and surgery. For patients with ongoing symptoms, the 30-day mortality rate was 6%, even after a 7-week delay, the researchers found. After adjusting for other risk factors, the odds of death were increased 3.6 to 4.1 times in patients operated on within six weeks after the diagnosis of COVID-19. “Patients with ongoing symptoms at least seven weeks after diagnosis may benefit from a new delay” in surgery, the researchers said. (bit.ly/3bLbFim)
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Nancy Lapid Reports; Edited by Bill Berkrot