Vaccination during pregnancy reduces infections in infants; vaccines only modestly reduce long-term COVID risk

June 2 (Reuters) – The following is a summary of some recent studies of COVID-19. They include research that warrants further study to confirm the findings and has yet to be certified by peer review.

Vaccines during pregnancy reduce infants’ COVID-19 risk

Vaccination against COVID-19 during pregnancy appears to lower the risk of coronavirus infection in newborns, according to a study in Norway.

Norwegian researchers followed 9,739 babies whose mothers received a second or third dose of a Pfizer COVID-19 vaccine. got (PFE.N)/BioNTech (22UAy.DE) or Moderna (MRNA.O) during pregnancy and 11,904 babies whose mothers have not been vaccinated before or during pregnancy. Overall, COVID infections were rare in the babies. But the risk of a positive COVID-19 PCR test during the first four months of life was 71% lower during the Delta era and 33% lower when Omicron was dominant for babies whose mothers were vaccinated during pregnancy compared to babies from unvaccinated mothers, the researchers reported on Wednesday in JAMA Internal Medicine†

“There may still be a protective effect of antibodies after the first four months, but there are likely to be individual differences,” says Dr. Ellen Oen Carlsen of the Norwegian Institute of Public Health. Babies get a different type of antibodies from breast milk, she noted, and the findings may be due in part to antibodies acquired through breastfeeding, or because vaccinated mothers are less likely to get COVID-19 and infect their babies.

Babies born to women who received a booster shot during pregnancy had an even lower risk of COVID-19 than those born to women who received only the original two-shot regimen. “This could mean that women who have been vaccinated with two doses before pregnancy should consider getting a booster dose during the latter parts of pregnancy,” Carlsen said.

Vaccines only modestly reduce long-term COVID risk

The risk of developing long-term COVID after infection with the coronavirus is lower for vaccinated people than for unvaccinated people, but not much, according to a large study by the US Department of Veterans Affairs.

Researchers compared outcomes among nearly 34,000 people who had breakthrough SARS-CoV-2 infections after receiving vaccines from Johnson & Johnson (JNJ.N)Pfizer (PFE.N)/BioNTech (22UAy.DE) or Moderna (MRNA.O), and more than 113,000 unvaccinated people who were infected. The study, conducted when the Delta variant was dominant, was published in naturopathy, found that vaccination reduced the chance of long-term COVID after infection by only about 15%. There was no difference in type or severity of long-term COVID symptoms between vaccinated and unvaccinated patients.

The researchers also compared hospitalized patients with breakthrough COVID to hospitalized patients with seasonal flu. “Breakthrough SARS-CoV-2 was associated with a higher risk of death…than flu,” said study leader Dr. Ziyad Al-Aly of the VA St. Louis Health Care System in a tweet. “The findings indicate that relying on vaccines as our only line of defense is not an optimal strategy,” he told Reuters.

Impact of coronavirus variants is location dependent

A new approach to viewing viral evolution could help predict whether and when a new coronavirus variant is likely to outpace current dominant versions, researchers say.

“Mutations alone cannot answer the question” of whether a variant will hold up, said Venky Soundararajan of Massachusetts-based data analytics firm nference. To estimate the potential impact of a variant, the “distinguishability” of its mutated gene sequences from previously circulating variants must be considered in the context of each geographic region, Soundararajan said. Genetic changes that confer distinctiveness in one geographic region may not do so in another region, depending on which variants were distributed there, his team said in a report published Thursday at medRxiv in anticipation of peer review† The researchers studied a database of nearly 8 million SARS-CoV-2 samples from around the world and tracked and compared the evolving genetic sequences of the variants that populations in different regions have been exposed to — so-called herd exposure. The distinctiveness of an ancestry in a particular country during a specific time window was significantly linked to the change in prevalence in that country over the next eight weeks, they found.

The researchers are working with the US National Institutes of Health on a system that will alert public health officials when new variants emerge to which communities are likely to be vulnerable. These are variants that show the most differences, both from the original version of the virus on which current COVID-19 vaccines are based, and from variants against which local residents have acquired some immunity through exposure of the herd.

Click for a Reuters image on vaccines in development.

Reporting by Nancy Lapid; Editing by Bill Berkrot

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