India's steady uptick in new COVID-19 cases is continuing at full speed, but the rate of hospitalization has remained low. The country logged nearly 2,600 new infections in 24 hours, with the number of active cases inching toward 16,000. Meanwhile, as many as 44 deaths were reported on Sunday, taking the country's official death toll up to 522,193.

Experts say, however, that the government-reported death toll is a drastic underestimation of the true number of deaths in India related to the virus.

In response to the rising infections, states, including Delhi, Maharashtra, Haryana, Mizoram and Uttar Pradesh, have brought back mask mandates, and increased vigilance in monitoring infection clusters and tracking variants. Those five states account for nearly 75% of all of the new cases.

"There are a few states which are reporting a higher contribution to India's cases. The ministry has advised following a risk-assessment based approach on allowing economic and social activities," Rajesh Bhushan, the secretary of the Health and Family Welfare Ministry, said in a statement.

Record daily spike in cases

The national capital, Delhi, reported more than 1,000 cases over 24 hours, in its highest daily spike since February 10. Prime Minister Narendra Modi is expected to chair a COVID review meeting this week.

Scientists and epidemiologists say the increase in cases could reflect the increased transmissibility of a new subvariant of omicron, BA.2.12.1, which has recently been seen in sequencing studies in Delhi. However, this increase in cases has so far not been reflected in hospital or ICU admissions.

"There is every possibility that it will only very rarely lead to serious disease in people who have been vaccinated or have hybrid immunity. It is this that we should look for and not the infection numbers, which can fluctuate," Gautam Menon, a professor of physics and biology at Ashoka University, told DW.

Vineeta Bal, from the Indian Institute of Science Education and Research, Pune, told DW that the coronavirus would likely continue to spread through small outbreaks across the country.

"When the virus finds enough vulnerable hosts, it will continue to exist and continue to mutate. In general, vaccination has resulted in a significant decrease in serious COVID disease, and that in itself is an achievement," Bal said.

"Vaccination in children has started more recently, and they will remain vulnerable to infection until fully vaccinated, even though most of them will not become seriously ill," he added.

With nearly 98% of the adult population in India covered with at least one COVID-19 vaccine dose, and nearly 84% having been fully inoculated, India has built a strong shield against the notorious pathogen that has killed millions globally over the last two years.

WHO reports significantly higher death toll

Last week, The New York Times, reported that the release of a report by the World Health Organization (WHO) had been delayed for months because of objections from India by disputing the calculation of how many people had died there from COVID-19.

According to the report, the COVID-19 excess death toll in India is estimated to be abound 4 million — or about eight times the current official figure of 520,000. Similar reports have come out in such reputed journals as The Lancet and Science.

The Health Ministry issued a statement in response to the WHO's figures on the same day.

The ministry said the model of calculating the deaths was flawed and treated all countries with a "one-size-fits-all" model. It also argued that India is a large country, and, owing to its large population and geographical area, it should be studied differently from the smaller countries.

But not everyone is convinced by the Indian government's explanation.

"It is not just about the WHO estimate or methodology. There have been multiple estimates using different data sources and different methodologies and all point to about 3 to 4 million excess deaths in India over the last two years," Brahmar Mukherjee, an Indian-American biostatistician and data scientist, told DW.

Mukherjee said the concerns raised by the government revealed incomplete and inaccurate understanding of the methodology.

"For example, it is not true that a model constructed for other countries was blindly applied to India. The technical team spent an incredible amount of time producing robust estimates and conducting sensitivity analysis," she said

Menon said she did not believe that the numbers had been by and large fudged deliberately, but that they simply reflect preexisting problems with collecting accurate statistics on health care data.

"However, it seems likely from broad epidemiological principles that deaths have been undercounted by a factor of four at least, although the WHO numbers are still larger," Menon said.

Prabhat Jha, an epidemiologist and director of the Center for Global Health Research in Toronto, who has worked closely on the issue, told DW that it was apparent that the official number of COVID-19 cases and deaths in India were substantially underestimated.

During the second wave of the COVID-19 pandemic in India, people witnessed distressing scenes of floating corpses in the Ganges, long queues outside crematoriums, full crematoriums with several pyres burning simultaneously, and riverbeds strewn with numerous unmarked graves.

"It would be of great help if India released all-cause mortality data for the whole nation for the last two years. Then one does not have to extrapolate from the subnational data, and this additional data can help improve the precision of the estimates," Mukherjee said.

Edited by: Leah Carter