Antibody measurement after vaccination can quicken clinical trials: US govt

Antibody measurements shortly after people were vaccinated against COVID-19 revealed the potential for speedier clinical trials of new vaccine candidates with fewer participants, NIH said

Antibody measurements shortly after people were vaccinated against COVID-19 revealed the potential for speedier clinical trials of new vaccine candidates with fewer participants, the National Institutes of Health (NIH) said.

"In people who received two doses of the Moderna COVID-19 vaccine, levels of antibodies found in the blood correlated with protection against illness," NIH said in a press release on Tuesday.

"The findings show that measurement of certain antibody levels could allow for smaller, faster studies of vaccines against COVID-19 variants."

Researchers with the Fred Hutchinson Cancer Research Center measured antibodies of more than 1,000 Moderna COVID-19 vaccine recipients to look for associations between antibody levels and the risk of symptomatic breakthrough infections, the release said.

The team measured binding antibodies, which bind viruses to tag them for destruction, and neutralizing antibodies, which stop viruses from infecting cells by blocking the parts they need to enter, the release also said.

For people with no detectable neutralizing antibodies, the vaccine was only 51 per cent effective. For people with the highest levels, it was 98 per cent effective. Both types of antibodies had similar associations with vaccine effectiveness, the release added.

Researchers, however, said it is not yet known whether short-term antibody measures correlate with long-term protection, although study participants will be monitored for two years, according to the release.