In this week’s review, the latest scientific research on coronaviruses and efforts to find treatments and vaccines show that the rare cardiac effects of vaccines usually improve rapidly, and the accuracy of experimental saliva tests almost matches that of PCR.
According to preliminary findings, survivors who were previously infected with the virus that causes COVID-19 (known as SARS-CoV-2) may be at higher risk of re-infection with the omicron variant than earlier versions of the virus. In South Africa, where omicron was first reported, researchers reviewed data on nearly 2.8 million infections and found that when early beta and delta variants spread during the second and third waves of the pandemic, the risk of first infection increases. But the risk of re-infection may increase. The infection rate is very low and has not changed. But last month, with the spread of omicron, the number of daily re-infections surged. Researchers reported on the medRxiv website on Thursday before peer review. They say that the risk of survivors' re-infection may rise faster than ordinary people's risk of the first infection. SARS-CoV-2 infection is usually diagnosed without genetic sequencing to confirm the relevant mutations, so this study cannot prove that omicron can better evade the body's immune defenses against previous infections. Nor can it prove the defenses produced by vaccination. Nonetheless, the researchers stated that the increased time to reinfection "strongly suggests that they are driven by the emergence of omicron variants."
According to data from Israel, the booster injection of the Pfizer/BioNTech COVID-19 vaccine seems to provide strong protection at least in the short term. The data shows that compared with adults who received the second dose of the vaccine more than five months ago, adults who received the third dose of the vaccine have a much lower chance of testing positive for coronavirus. Researchers at Maccabi Health Services reviewed data from PCR tests performed on more than 306,000 adults after Pfizer/BioNTech booster doses are widely available. Approximately half of the tests were conducted in people who received the booster, and the other half was conducted in people who received only the standard two doses, at least five months before the second vaccination. Researchers reported in JAMA Internal Medicine last week that, overall, 1.8% of the booster group tested positive, compared to 6.6% of those tests that received only two doses. After considering various risk factors of the participants, they estimated that within 4 to 9 weeks after receiving the third shot, the chance of testing positive for the virus was reduced by 86%. When researchers compared two or three doses of closely matched subsets of recipients, the results were similar. The researchers said that over time, the protective effect of the vaccine "seems to be offset by the third dose in a short period of time", but longer monitoring is needed to understand how long the protective effect will last.
According to a report published on Monday by the American Heart Association (AHA) magazine "Circulation", a small number of pediatric recipients of the COVID-19 vaccine developed myocardial inflammation called myocarditis, which may have mild symptoms but will improve quickly. This rare side effect is most common in adolescents and young adult men. Researchers reviewed data from 26 children's hospitals in the United States and Canada, focusing on 49 patients aged 12 to 20 who were hospitalized with "diagnosed" myocarditis within one month of vaccination and 91 "probable" myocarditis patients. The majority (91%) are men, 66% are white, and the average age is about 16 years. Although 19% required intensive care, no one died. Half of the patients were sent home within two days. The researchers said that although myocarditis associated with the COVID-19 vaccine is usually mild and usually resolves quickly, the condition is still "very worrying" and it is not clear how the patient's long-term condition is. Nonetheless, they concluded that “the risk must be balanced with the critical illness and cardiovascular involvement associated with COVID-19.” In a press statement, Dr. Donald Lloyd-Jones, chairman of the AHA who was not involved in the study, said that the data showed that the benefits of COVID-19 vaccination "far outweigh the risks of very rare adverse events, including myocarditis."
British researchers have found that the method of mixing and matching COVID-19 vaccines is safe and effective, and some combinations can even improve the immune response.
They studied 1,079 volunteers, and their first shot was either AstraZeneca's adenovirus vector vaccine or Pfizer/BioNTech's mRNA vaccine. Then, the participants were randomly assigned to receive the same vaccine or Moderna's high-dose mRNA vaccine or experimental Novavax vaccine injection, which uses a different technology from other vaccines.
The research team reported in The Lancet on Monday that the mixed vaccine did not produce any adverse effects. Laboratory experiments have shown that no matter which injection people receive first, getting Moderna as a second dose will produce a stronger antibody response than the second dose of the original vaccine.
The researchers found that an important second-line response from the immune system-T cell activation-is most evident in the AstraZeneca vaccine, followed by the Novavax vaccine. Given that none of these require special frozen storage, this finding — and the fact that it is safe to mix any other tested vaccine — may be “closely related to 94% of people in low-income countries who have not received any doses,” they concluded road.
Researchers believe that the experimental saliva test can diagnose SARS-CoV-2 infection within minutes, almost as accurate as the gold standard PCR test.
Unless it is done immediately after a night of fasting, a typical saliva test is unreliable because the concentration of virus particles in the saliva drops sharply after eating or drinking. Like other rapid antigen tests, this test called PASPORT combines viruses with nanoparticles. But researchers reported on Microchimica Acta on Monday that PASPORT added a second type of nanoparticle, which would combine with the first group to produce a stronger signal and make detection more sensitive at any time of the day. A virus was found.
Tested on non-fasting samples from 139 volunteers — 35 of whom had known COVID-19 infections and 19 of them with other respiratory infections — and compared with PCR testing of swab samples from the back of the nose and throat In comparison, PASPORT’s accuracy in identifying SARS is 97%-CoV-2 and 91% accuracy exclude it.
“Although PCR has always been the gold standard, it requires well-trained personnel and laboratory infrastructure,” said Dr. Danny Jian Hang Tng, head of research at Singapore General Hospital and Duke-NUS Medical School in a statement. Reliable, painless, affordable and convenient saliva testing "will encourage more testing and more frequent testing."
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