By Nancy Lapid
March 15 (Reuters) – The following is a summary of some of the latest scientific studies on the new coronavirus and efforts to find treatments and vaccines for COVID-19, the disease caused by the virus.
mRNA vaccines stimulate lymph nodes for longer-term protection
Along with the application of antibodies for immediate defense, mRNA vaccines against COVID-19 also stimulate the lymph nodes to stimulate immune cells that provide long-term protection, a new study confirms. The early wave antibodies are generated by B cells called plasma blasts. In healthy volunteers, blood tests showed that two doses of the Pfizer / BioNTech vaccine “caused a strong plasma blast reaction,” said co-author Ali Ellebedy of the Washington University School of Medicine in St. Louis. Louis said. The immune cells that will produce antibodies in the coming year, called memory B cells, are generated by B cells that occur only in lymph nodes near the vaccine for injections, his team explained in a paper currently being published. in a Nature journal. In repeated biopsies of volunteers’ lymph nodes, “we saw a strong response to the germ center,” Ellebedy said. The responses lasted at least seven weeks, “without it going to cool off any time soon,” he added. “Although we do not yet have long-term samples, it is safe to assume given the extent and persistence of the germ response that those individuals will develop a lasting immune response” on mRNA vaccines. The Moderna Inc. vaccine also uses mRNA technology. (https://bit.ly/3tnAiYw)
The accuracy of the throat swab may vary according to the time of day
The accuracy of gold standard PCR tests of samples of nasopharyngeal swab may vary according to the time of day, according to new data. Researchers analyzed 31,094 tests performed on symptomatic and asymptomatic individuals on 127 tests, including 2,438 tests that showed COVID-19. In an article published on medRxiv before peer review on Saturday, they report that the tests were likely to be positive around 2pm – and the share of positive tests in the early afternoon was twice as high as the lowest percentage found on others that day. The study “suggests that people may be more contagious at certain times of the day and this raises questions about whether tests for SARS-CoV-2 may be less accurate when collected between late evening and early morning,” said co-author , dr. Candace McNaughton, said. of Vanderbilt University. “If our findings are confirmed, clinicians and public health teams can focus their efforts on reducing the risk of viral spread during times of peak viral shedding,” she said. This may involve emphasizing the mask from noon to early afternoon at home while setting it apart, or encouraging early-morning shopping for vulnerable populations. “There may be greater benefit in repeat tests if a negative test is collected when viral error is generally less,” McNaughton said. (https://bit.ly/2NjcZiY)
Delay of operation is recommended after COVID-19
If possible, surgery should be delayed for at least seven weeks after infection with the new coronavirus, and patients who still have symptoms at that stage may benefit from further delay, researchers recommend in anesthesia. They reviewed data on 140,231 surgery patients from 116 countries, including 3,127 with a history of COVID-19. The mortality rate 30 days after surgery was 1.4% in patients who had never had COVID-19. It was 9.1% among patients diagnosed within two weeks before surgery, 6.9% among those diagnosed within 3 to 4 weeks, and 5.5% when diagnosed 5 to 6 weeks before surgery. . The mortality rate dropped to 2% when at least 7 weeks elapsed between diagnosis and surgery. For patients with persistent symptoms, the 30-day mortality rate was 6% even after a 7-week delay, researchers found. After adjusting for other risk factors, the chance of death within six weeks after a COVID-19 diagnosis is increased 3.6-to-4-fold in patients who have undergone surgery. “Patients with persistent symptoms that are at least seven weeks after diagnosis may benefit from further delay” of their surgery, the researchers said. (https://bit.ly/3bLbFim)
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(Reporting by Nancy Lapid; Edited by Bill Berkrot)