A new study published in one of the most prestigious peer-reviewed medical journals shows that the Pfizer vaccine is largely ineffective against the dominant local variant of the novel coronavirus that causes COVID-19 in South Africa.

The worrying results of the fresh study were published in the New England Journal of Medicine on Wednesday, suggesting that the African variant of the coronavirus may decrease antibody protection from Pfizer’s COVID-19 vaccine by two-thirds.

The South African government is counting on the Pfizer vaccine, developed with German partner BioNTech, to boost its COVID-19 vaccination program in the coming months.

The new study comes less than two weeks after interim data on British drugmaker AstraZeneca’s COVID-19 vaccine also heightened concerns about its efficacy against the more contagious South African variant, prompting Johannesburg to temporarily postpone the rollout of the AstraZeneca vaccine.

The detailed laboratory study took into account all the key mutations of the 501Y.V2 variant, whereas a paper released late last month only measured the impact of three key mutations of the variant on the Pfizer vaccine.

The African country, with nearly 1.5 million cases and about 48,500 deaths, has recorded nearly half the COVID-19 fatalities and more than a third of confirmed infections in the entire continent.

The South African strain shares some of the mutations with the previously discovered UK variant, known as B.1.1.7.

SS