Researchers are looking for powerful antibodies against many variants; advanced cases may be less infectious

August 23 (Reuters) – Here is a summary of some recent studies on COVID-19. They include research that justifies a subsequent study to corroborate the findings and has not yet been certified by the peer review.

Researchers working towards a vaccine for many variants

Last week, two different research teams reported on laboratory tests of monoclonal antibodies that appear to protect against a wide range of COVID-19 virus variants. A study, published Wednesday in the New England Journal of Medicine, identified “high-level, broad-spectrum” antibodies in blood samples from survivors of the original SARS outbreak in 2003 who recently received the Pfizer / BioNTech vaccine against SARS- CoV-2, the virus that causes COVID-19. In test-tube experiments, some of the antibodies from vaccine-induced SARS survivors could neutralize not only all current variants of SARS-CoV-2 concern, but also five viruses that have been identified in bats and pangolins and have the potential to cause human infection. In a separate study, published Thursday in the journal Immunity, another research team describes an antibody that was highly protective at low doses against a wide range of COVID-19-causing variants in mice. “The antibody binds to a part of the virus that differs little between variants, meaning that resistance is unlikely to appear at this point,” the authors said. The results of these studies could be a step toward developing new antibodies that would be effective against multiple different coronaviruses, according to both teams.

The spread of infectious viruses may be less in advanced cases

A new study suggests that people vaccinated who become infected with COVID-19 have high levels of virus in their nose and throat, but not all of this virus is infectious. Among the 24,706 vaccinated health workers in the Netherlands, 161 developed mild or asymptomatic infections, mainly due to the Delta variant of the coronavirus. Viral levels in nose and throat swab samples from these patients were as high as in unvaccinated health workers who were infected last year with the original strain of the virus. But in experiments with test tubes, the vaccinated patient virus was less efficient in reproducing than the unvaccinated patient virus, probably because some of them had been neutralized by vaccine antibodies, the researchers speculate. In a report published in medRxiv on Saturday before the peer review, they conclude that the reduction in infectious viruses is reduced in advanced cases, although patients are still contagious.

Antibodies fade faster after the vaccine versus the actual infection

Protective antibody levels decrease more rapidly in Pfizer / BioNTech COVID-19 mRNA vaccine receptors than in COVID-19 survivors, according to doctors at one of Israel’s largest HMOs. They monitored antibody levels in 2,653 adults who received two doses of the vaccine and in 4,361 COVID-19 survivors who were never vaccinated. Antibody levels fell by up to 40% per month in vaccinated participants, compared with less than 5% per month in so-called convalescents. After six months, about 84% of vaccine recipients still had detectable antibodies, while approximately 90% of convalescents still had detectable antibodies after nine months. Dr. Ariel Israel of Leumit Health Services, co-author of a report published Sunday in medRxiv prior to the peer review, noted that antibodies are not the only weapon in the immune system against the virus. However, he said, the data suggest that antibody protection in Pfizer vaccine receptors is declining at a higher rate than in COVID-19 survivors. Leumit researchers had already reported that advanced infection rates increase from five months after vaccination. Dr. Israel said the combined data argue for a booster shot five months after the second injection, especially for high-risk individuals.

Click for a Reuters chart on developing vaccines.

Nancy Lapid Reports; Edited by Tiffany Wu

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