(Bloomberg) -- South Africa has held extensive talks with the manufacturers of Russia’s Sputnik V vaccine and has concerns about its efficacy against a variant of the coronavirus first identified in the country, a government official said.

The country is also concerned about the adenovirus 5 vector used in the shot, which has in previous studies appeared to make people more susceptible to HIV infection, Anban Pillay, deputy director-general in the Department of Health, said on a webinar on Tuesday.

The country’s health authorities don’t think that the vaccine produced by Novavax Inc. is suitable for the country because of its low efficacy against the variant, he said. Talks have been held with India’s Bharat Biotech International Ltd., he said.

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