The uptick in daily Covid-19 deaths in China has put the spotlight back on the coronavirus pandemic.

The country’s health infrastructure is swamped with patients and the waiting period is growing longer at funeral homes.

Globally, scientists are concerned that the rapid spread of the disease across China could help the coronavirus mutate faster, creating newer variants. With no restrictions on international travel, new variants could easily spread to other countries.

In India, the health ministry this week advised states to send all positive Covid-19 samples for genome sequencing and asked laboratories to keep an eye out for newer variants. It also ordered airports to test 2% of incoming international passengers for Covid-19.

What does the surge in China mean for India? Do Indians need to rush to take a booster shot? spoke to experts about these and other questions.

What is causing the present surge in China?

China is seeing a much higher and steeper wave than it witnessed when the pandemic first broke out in the country in 2019. Experts say this is because the Chinese government inordinately delayed lifting Covid-19 restrictions, and then lifted them dramatically without protecting its population well.

Vinod Scaria, scientist at CSIR-Institute of Genomics and Integrative Biology, said China’s Zero-Covid policy ensured that the virus was restricted from circulation in the Chinese population for first three years of the pandemic, while the virus was spreading across the globe. As the virus jumped from one human to another, it mutated, evolved and became fitter to transmit faster and better.

In early December, China lifted all its restrictions against Covid following mass public protests. This allowed new variants of Sars-CoV-2, chiefly the Omicron variant’s family, which are better adept at evading immunity than the original variant, to circulate rapidly in the country.

“This would mean a large proportion of the population is susceptible to a rapidly spreading and immune evasive version of the virus,” Scaria said. China has a large ageing population which increases risk of severe infection in them, he added.

Epidemiologist Chandrakant Lahariya listed several other reasons contributing to the surge of cases in China. First, Sinopharm and Sinovac, the vaccines produced and administered in the country, have not been as effective as mRNA vaccines. Two, the country has had a poor booster dose coverage. Three, its population has no immunity induced by natural infection.

According to one projection, China could witness between 1.3 million to 2 million deaths in the current surge. Another projection estimates a million deaths. But Lahariya cautioned that these projections may not be reliable since China does not share data.

Source: Airfinity's risk analysis report

Why are other countries also seeing a rise in cases?

In addition to China, the United States, Japan, Korea and Brazil have also recorded a rise in cases recently. But experts say this is not connected to the surge in China.

“Vaccination began early in these three countries. There is waning immunity,” said Dr Sushant Sahastrabuddhe, epidemiologist and director of enteric fever at International Vaccine Institute in South Korea.

In addition, weather conditions in these countries are enabling the virus to spread. “This time we have a harsher winter,” Sahastrabuddhe said. “In Korea and Japan, it is snowing.”

Is India likely to see a fresh wave of cases?

Most experts believe the worst phase of the pandemic in India is over. Unlike the Chinese, the Indian population has hybrid immunity, induced by widespread natural infection caused by two waves in 2021 and 2022, and immunity generated through vaccines. Cases have been steadily declining in the country, with the daily tally of fresh cases down to 153, with zero deaths.

Even if the country sees a rise in cases, experts say it is unlikely to witness a large wave.

The variant associated with the current surge in China is BF.7, shorter for BA., is a sub-variant of BA.5 that has derived from the parent Omicron variant. The variant is not new: it has been in circulation in over 90 countries, including India, for a few months now.

Dr Rajesh Pandey, scientist at CSIR-Institute of Genomics and Integrative Biology (IGIB), told that BF.7 and whole compendium of variants are under monitoring and no red flags have been seen yet.

According to virologist Dr Gagandeep Kang, BF.7, and another Omicron sub-variant XBB, both considered highly infectious, have not driven a surge in India. “In the absence of an even more highly infectious variant, I do not expect a surge,” she noted.

Epidemiologist Lahariya agreed. The virus has already widely travelled in Indian population. “We do not have anything to worry here,” he said.

Sahastrabuddhe said lack of social distancing and a surge in travel may lead to a rise in cases in India. But, compared to previous waves, “fewer numbers of people will get infected and die,” he added.

Should Indians take a booster dose?

Over 95 crore Indians have been recieved two doses of the Covid-19 vaccines. Of them, 22.2 crore or 23.3% have also received a booster shot. Currently, India permits only one booster dose. It has still not approved a second booster shot, since experts say it is not needed.

Lahariya explained that the role of a booster dose is limited in India, since transmission of the infection has been high. “But if people want to take a booster dose, they can. It will not prevent infection though,” he said.

While younger age groups may not need a booster dose, most experts agree that it could help protect vulnerable people, including those above the age of 60 and those with multiple co-morbidities. “Vaccines do have some efficacy against the Omicron variant,” Sahastrabudhe said, adding that if Covid-19 cases indeed rise in India and the government has to prioritise, then it should first provide boosters to vulnerable groups.

Pandey from CSIR-IGIB said there was no harm in taking a precautionary booster dose. “I am 43 and have no comorbidity, and I have taken a booster,” he said.

A scientist from the same organisation, however, raised concerns over the current vaccines available in India and their diminished efficacy against Omicron. “They are efficacious against the original strain but not as effective against Omicron variant,” the official said, requesting anonymity.

Kang, who also works with Christian Medical College in Vellore, said for elderly people, a booster is a must even if there is no data of efficacy of the Indian vaccines. “For younger healthier people, the value is likely to be less, but not zero,” she said.