Taiwan became the latest place to ban arrivals from coronavirus-stricken India on Monday.

The variant, B.1.617, has reached at least 17 countries, from Britain and Iran to Switzerland, sparking global concern and spurring several to close their borders to people travelling from India.

Scientists are studying whether the variant, resulting from two key mutations to the outer “spike” portion of the virus that attaches to human cells, is driving an unexpected explosion in cases in India.

India’s tally of infections was just shy of 20 million on Monday, after it reported more than 300,000 new coronavirus cases for a 12th straight day.