BEIJING (Reuters). – Sinopharm’s protein-based COVID-19-vaccine elicited a stronger immune response than a third dose.

This study was published Tuesday without peer review. It came amid concern over Sinopharm’s BBIBP–CorV shot (one of two COVID-19 vaccines that China exports most effectively against Omicron variant), and its effectiveness.

In a previous study, it was found that Omicron neutralization by a BBIBP CorV booster is weaker than for an older strain of coronavirus from Wuhan.

Sinopharm’s NVSI-04-07, a protein-based vaccine that is approved by the United Arab Emirates for immediate booster use, uses a different technology from the BBIBP CorV shot, which contains inactivated forms of coronavirus.

Researchers found that the Omicron neutralizing antibody levels in healthy adult vaccine recipients who had received two BBIBP CorV doses over six months were significantly higher than those who received an NVSI-06/07 booster.

However, the antibody-based results differ from those derived from efficacy readings relating to how effectively the NVSI06/07 booster after BBIBP CorV vaccine would protect individuals from Omicron disease.

The paper’s authors, which included researchers from Sinopharm’s units as well as Sheikh Khalifa Medical City of Abu Dhabi, warned that it was still unclear how long the NVSI06-07 booster would be effective.