New York : The World Health Organization (WHO) on Sunday warned that the newer Omicron variant (B.1.1.529) of SARS-CoV-2 is more transmissible than the Delta strain and reduces vaccine efficiency but caused less severe symptoms, based on early data, according to several news reports.

However, the global health body also said that it could not ascertain if the higher rate of transmission was because it was less prone to immune responses or a higher transmissibility or a combination of both because of a lack of data, news agency AFP reported.

According to the WHO, early evidence suggested that the newer variant Omicron caused “a reduction in vaccine efficacy against infection and transmission,” the global health body said in a technical brief. “Given the current available data, it is likely that Omicron will outpace the Delta variant where community transmission occurs,” it further said.

Meanwhile, Omicron cases have been reported from as many as 63 countries as of December 9, the UN health body noted. The UK, South Africa were among the countries where faster transmission of the cases have been noted. The Delta variant, previously, was less prevalent in South Africa while it was the dominant variant in Britain.

In India, several states and districts reported cases of Omicron variant on Sunday as the total caseload pertaining to the strain reached 38.

The variant was first identified in South Africa and the WHO announced it as a variant of concern back in November.

Covid-19 vaccine makers Pfizer and BioNTech had said last week that three doses of their vaccine appeared effective against the variant, based on initial laboratory tests.