Gilead's remdesivir fails to show benefit in European trial; no fetus risk seen with first trimester vaccination

The following is a summary of some recent studies on COVID-19. They include research that warrants further study to corroborate the findings and that has yet to be certified by peer review.

Two promising drugs for COVID-19 fail to deliver

Two drugs that looked like promising treatments for COVID-19 in preliminary studies - remdesivir for hospitalised patients and camostat for patients who are not seriously ill - failed to show a benefit in those groups in randomised controlled trials, researchers reported in two separate papers.

In five European countries, researchers studied 843 COVID-19 patients who were hospitalised between March 2020 and January 2021 and who needed oxygen or machines to help with breathing. Two week after patients had received either Gilead Sciences' antiviral remdesivir - sold as Veklury - plus standard of care or standard of care alone for up to 10 days, there was no difference between the groups in signs of improvement, investigators reported on Thursday.

In Japan between November 2020 and March 2021, researchers randomly assigned 155 patients with mild or moderate COVID-19 to receive the pancreatitis drug camostat mesylate from Ono Pharmaceutical Co 4528.T or a placebo for up to 14 days. Camostat blocks an enzyme that helps some versions of the coronavirus infect cells - including the variants circulating at the time of the study - but did not help patients get rid of the virus in their airways any faster than placebo, the Japanese researchers reported on Saturday. They said the results "highlight... the necessity of conducting well-designed studies to confirm whether preclinical findings translate into meaningful clinical efficacy." Both studies were posted on medRxiv ahead of peer review.

COVID-19 vaccines in first trimester of pregnancy appear safe

COVID-19 vaccination during the first trimester of pregnancy does not increase the risk for congenital defects in the fetus, preliminary data suggest.

Researchers at Northwestern University Feinberg School of Medicine in Chicago studied 1,149 women who received at least one dose of a vaccine from Moderna, Pfizer or Johnson & Johnson between 30 days before conception and 14 weeks into gestation, which is when the fetus is most vulnerable to developing birth defects due to medications taken by the mother. Compared to 2,007 pregnant women who either remained unvaccinated or were vaccinated later, women vaccinated shortly before or early in pregnancy were not at higher risk for having an abnormality in the fetus detected by their doctors on an ultrasound exam, according to a report published on Monday in JAMA Pediatrics.

The authors acknowledge that examining a fetus with ultrasonography is not as reliable as examining an infant, and because many of the women they studied are still pregnant, real proof of vaccination safety in the first trimester requires larger studies of newborns.

SARS-CoV-2 infects eye cells in test tubes

The coronavirus that causes COVID-19 can infect the vision-processing cells of the eye and reproduce there, lab experiments suggest.

Researchers used human cells in test tubes to grow a miniaturised, simplified version of the retina - the nerve tissue at the back of the eye that receives images and sends them as electric signals to the brain. When the researchers exposed these "organoids" to SARS-CoV-2, the virus infected a variety of retinal nerve cells that perform different functions. Furthermore, the virus could make copies of itself in those cells, the researchers reported in the journal Stem Cell Reports. In the infected organoids, genes that increase levels of inflammatory proteins associated with retinal damage were more active, the researchers also found. They also found that younger retinal cells were more vulnerable to the virus, possibly because younger cells have more of the protein on their surfaces that the virus uses as a gateway for entry.

Antibodies that block those gateways and make it harder for the virus to infect cells appeared to protect the retinal organoids, further experiments showed. The findings suggest that the persistent syndrome known as long COVID may also include retinal problems, researchers said.