MRNA vaccines stimulate the lymph nodes for long-term protection; The accuracy of the COVID-19 test may vary depending on the time of day

(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 the lymph nodes for long-term protection

Along with inducing antibodies for immediate defense, mRNA vaccines against COVID-19 also stimulate lymph nodes to generate immune cells that provide long-term protection, a new study confirms. The early wave of antibodies is generated by B cells called plasmablasts. In healthy volunteers, blood tests showed that two doses of Pfizer / BioNTech vaccine induced “a strong plasmablast response,” said co-author Ali Ellebedy of Washington University School of Medicine in St. Louis. The immune cells that will produce antibodies after exposure to the virus in the coming years – called memory B cells – are generated by germ cells in the germ center that are found only in the lymph nodes near the vaccine injection sites, his team said in a statement. peer review work possible publication in a journal Nature. In repeated biopsies of volunteers’ lymph nodes, “we saw a robust germinal response,” Ellebedy said. The answers lasted at least seven weeks, “without any signs of cooling soon,” he added. Although we do not yet have long-term evidence, it is safe to assume, given the magnitude and persistence of the germline reaction, that those individuals will develop a lasting immune response to mRNA vaccines. Modern Vaccine Inc. also uses mRNA technology. (bit.ly/3tnAiYw)

The accuracy of the neck swab test may vary depending on the time of day

The accuracy of gold standard PCR tests of nasopharyngeal buffer 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 posted on medRxiv on Saturday before the peer review, they report that the tests were most likely to be positive around 2 p.m., and the proportion of positive tests in the early afternoon was twice as high as smaller proportion observed at other times during 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 late evening and early morning,” said co-author Dr. Candace McNaughton of Vanderbilt University. “If our findings are confirmed, clinicians and public health teams could focus their efforts on reducing the risk of viral spread during peak viral periods,” she said. This could involve highlighting masking from mid-day to early afternoon at home while isolating yourself or encouraging early morning shopping for vulnerable populations. “There could 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 is recommended after COVID-19

Whenever possible, surgery should be postponed for at least seven weeks after infection with the new coronavirus, and patients who are still experiencing symptoms at that time may benefit from an additional delay, the researchers under anesthesia recommend. They reviewed data on 140,231 patients operated on in 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 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. 5-6 weeks preoperatively. The mortality rate dropped 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 chances of death increased 3.6 to 4.1 times in patients who underwent surgery within six weeks of being diagnosed with COVID-19. “Patients with ongoing symptoms at least seven weeks after diagnosis may benefit from an additional delay” in surgery, the researchers said. (bit.ly/3bLbFim)

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