No new coronavirus variants have emerged during China’s recent surge of Covid-19, scientists said on Wednesday, releasing a study that has vindicated Indian researchers who had challenged forecasts of a spillover surge in India.

The study has found that over 90 per cent of the local Covid-19 infections in Beijing — among the hardest hit cities in China — involved the sub-variants called BA.5.2 and BA.7 that emerged from the omicron subvariant, which had caused surges in India and other countries in early 2022.

Scientists say the new findings show that speculation about a possible spillover surge in India that had prompted the Union health ministry to issue cautionary advice to the Bharat Jodo Yatra and the Indian Medical Association’s caution about “an impending outbreak” were unfounded.

Health minister Mansukh Mandaviya had in December written to the Congress asking it to consider stopping the Yatra — a series of walks across the nation — if it cannot be held following Covid-19 protocols.

Through December, as new Covid-19 infections raged across China after the Chinese government lifted its earlier strict pandemic control policies, medical researchers in India had sought to allay fears of any spillover surge, asserting that Indians were protected through vaccination and infections.

Anurag Agrawal, a physician-researcher and dean of biosciences at Ashoka University, had predicted that omicron variants had swept through a billion people across India without evolving into new and more dangerous variants and there was no reason why they should do so in China.

The new study from China which covers infections between November 14 and December 20 has found that all 413 strains sequenced belonged to existing, known Covid-19 strains, with BF.7 accounting for 76 per cent and BF.7 accounting for 16 per cent of the cases.

“Two known variants — rather than any new variants — have been chiefly responsible for the current surge in Beijing and likely China as a whole,” said George Gao, the study’s lead author at the Institute of Microbiology at the Chinese Academy of Sciences. Gao and his colleagues published their findings in The Lancet on Wednesday.

“Omicron has evolved around the world — we have a soup of omicron variants at present,” said Rajesh Karyakarte, professor of microbiology at the BJ Medical College, Pune, who leads Maharashtra’s Covid-19 genome sequencing efforts.

“India has had cases of both BA.5.2 and BF.7 sub-variants but they could not establish themselves in the country where the BA.2.75 and XBB sublineages dominate,” Karyakarte said.

Scientists say immunity acquired through earlier infections and vaccination protects people from severe disease and only dramatic genetic changes in the virus that transforms the omicron into a significantly different variant could cause fresh surges in the future.

“What I would worry about is a jump of currently circulating variants into animals, acquisition of mutations that are harmless to the host animal, but increase virulence to humans, then a jump back into humans. That is what we need to build surveillance for going forward — while continuing human surveillance,” said Agrawal.