The Pfizer vaccine is slightly less effective but appears to still protect against the more transmissible Indian strain of the virus that causes Covid-19, according to a study by France's Pasteur Institute.

“Despite slightly diminished efficacy, the Pfizer vaccine probably protects” against the Indian variant, according to laboratory test results, said Olivier Schwartz, the institute's director and co-author of the study that was published ahead of peer review.

The study sampled 28 healthcare workers in the city of Orleans. Sixteen of them had received two doses of the Pfizer vaccine, while 12 had received one dose of the AstraZeneca vaccine, AFP reports.

People who had received two doses of Pfizer saw a three-fold reduction in their antibodies against the Indian variant, B.1.617, according to the study, but were still protected.