Pfizer vaccine less effective against Omicron variant, claims study

A major real-world study has suggested that Pfizer Covid vaccine has weaker efficacy against the Omicron variant. The study revealed that the Pfizer vaccine had efficacy of just 70 per cent against hospitalisation.

The study released on Tuesday by South Africa's largest private health insurance administrator, Discovery Health, was based on more than 211,000 positive COVID-19 test results. Around 78,000 of those results from Nov. 15 to Dec. 7 were attributed to Omicron.

The 78,000 results are not confirmed Omicron cases, meaning the study cannot offer conclusive findings about the variant labelled "of concern" by the World Health Organization and reported in more than 60 countries.

South African scientists have so far confirmed around 550 positive tests as being Omicron, with the variant accounting for 78% of sequences from November, more than the previously dominant Delta variant.

South Africa alerted the world to Omicron late last month, triggering alarm that it could cause another surge in global infections, and leading to the imposition of travel restrictions on southern Africa. South Africa's daily infections have since risen to around 20,000 in recent days.

The findings from a real-world analysis are some of the earliest on protection against Omicron outside of lab studies, which have shown reduced neutralising activity against the variant. read more

Based on analysis by Discovery's clinical research and actuarial teams, and in collaboration with the South African Medical Research Council, the study calculated that two doses of Pfizer-BioNTech offered 70% protection against hospitalisation compared with the unvaccinated during the recent surge in cases and 33% protection against infection.

It said this represents a drop from 80% protection against infection and compares with 93% efficacy against hospital admission during South Africa's outbreak of the Delta variant, which is the globally dominant variant and considered to be the most infectious to emerge during the pandemic.

Discovery cautioned that the study's findings should be considered preliminary.

(With inputs from agencies)