With India’s daily tally of COVID-19 infections surging by records, public health experts worry that a new — possibly more virulent — coronavirus variant could be racing through the crowded nation of more than 1.3 billion people.

The new variant, which has a so-called double mutation, is thought to be fueling India’s deadlier new wave of cases that has made it the world’s second worst-hit country, surpassing Brazil again, and has already begun to overwhelm its hospitals and crematoriums. India has reported more than 14.5 million COVID-19 cases so far and more than 175,600 fatalities.

"This is a variant of interest we are following,” Maria Van Kerkhove, the World Health Organization’s technical lead officer on COVID-19, told reporters Friday. "Having two of these mutations, which have been seen in other variants around the world, are concerning,” she said, adding that there was a similarity with mutations that increase transmission as well as reduce neutralization, possibly stunting the ability of vaccines to curb them.