NEW DELHI: A peer-reviewed study published in Nature Medicine found that while millions of people in 48 countries have received two shots of Sinovac, a Chinese-manufactured Covid-19 vaccine, the immunizations alone are ineffective against the Omicron variant.
Omicron infection elicited no neutralising antibodies among those who got the normal two-shot Sinovac vaccine regimen, according to a study of blood serum from 101 Dominican Republic residents.
Antibody levels against Omicron increased in those who also received a booster shot of Pfizer-mRNA BioNTech's vaccine, according to a new study from Yale University and the Dominican Republic.
When researchers compared these samples to blood serum samples maintained at Yale, they discovered that even those who had received two Sinovac shots plus a booster had antibody levels similar to those who had had two mRNA vaccine shots but no booster shot.
The two-shot mRNA regimen without a booster has been demonstrated in other studies to provide relatively minimal protection against Omicron. Persons who had been infected with earlier strains of the SARS-Cov-2 virus had limited immunological protection against Omicron, according to the researchers.