COVID-19 Omicron variant
Test tubes labelled "COVID-19 Omicron variant test positive" are seen in this illustration. Image Credit: REUTERS

A COVID-19 vaccine that can be produced locally in low- and middle-income countries is yielding promising results in early clinical trials, researchers say.

The NDV-HXP-S vaccine, developed at Icahn School of Medicine at Mount Sinai in New York City, uses an engineered version of the harmless Newcastle disease virus studded with coronavirus spike proteins to teach the immune system to recognise and attack the virus that causes COVID.

Using blood samples from trial participants, researchers found that NDV-HXP-S induces proportionally more antibodies that can neutralize the virus and fewer non-neutralizing antibodies than the current mRNA vaccines from Moderna or Pfizer/BioNTech, they reported on Friday on medRxiv ahead of peer review.

"The NDV-HXP-S vaccine induced neutralizing antibody responses against wild type (the original) SARS-CoV-2 that matched what we see after mRNA vaccination, but the proportion of neutralizing antibodies in the response was higher for NDV-HXP-S," said Mount Sinai's Florian Krammer.

The vaccine can be manufactured like flu vaccines at low cost in chicken eggs at influenza vaccine manufacturing plants around the world, his team said.

Early clinical trials with a live version are underway in Mexico and the United States, while an inactivated version is being tested in Vietnam, Thailand and Brazil, a spokesperson said.

Mid-stage trials of the inactivated vaccine have also been completed and pivotal randomized trials are being planned.