Why is Delhi seeing a third surge in Covid-19 cases even as most of India’s numbers are going down?

India may have seen its peak in terms of Covid-19 cases in September, with the graph resolutely pointing downwards since then, but its capital city has not been able to rest easy. That is because Delhi, after already dealing with two spikes in new cases in June and September, has in November seen its worst figures yet.

On November 19, the city recorded 7,546 new cases with 98 deaths, taking the total toll to 8,041. The highest number of cases had been reported on November 11 with around 8,593 cases. That week, the city recorded an average 7,000 fresh cases daily. On November 18, Delhi recorded 131 deaths, the highest so far because of the virus. Additionally, it recorded 21% of all new deaths in India in the past week, Livemint reported on November 19.

Chief Minister Arvind Kejriwal called this surge the “third wave” of the virus in Delhi. In response, the Delhi government has increased fines for not wearing masks from Rs 500 to Rs 2,000, withdrawn a decision to allow weddings with up to 200 guests and forwarded to the Central government a proposal to shut down markets that are seeing big crowds. Additionally, the Union Home Ministry has intervened to scale up RT-PCR testing to 60,000 per day by the end of November, and to increase the number of beds and facilities.

Why Delhi, why now?

For months experts have been warning of a likely spike in Covid-19 cases around India’s festive season, generally October and November annually. Yet the surge in Delhi seemed to surprise authorities, who scrambled to provide more facilities for the capital.

And the situation also brought up another question – why is only Delhi seeing the brunt of cases in a pan-Indian festive season?

According to some epidemiologists, the answer comes from the way the virus has travelled through the population of the capital, affecting the poor first – since they have no option to stay at home – and now reaching the more well-off who had started to step out.

“Each place, even though it is geographically the same, has different people, some people or communities that get infected fast… those who have to go for daily wage, the poorer section, they will get infected fast because they are exposed to it,” said Dr Jayprakash Muliyil, one of the country’s foremost epidemiologists.

Muliyil said that certain parts of Delhi had reached their threshold of immunity, while the transmission had increased among other susceptible populations.

“The poorer sections have finished their epidemic [in Delhi],” Dr Muliyil said. “Now, it is the richer groups that are getting infected. This is my impression. There may be a slight increase because people are gathering together, shopping together.”

Another expert concurred with Muliyil and said this was possible.

“What we are seeing now in Delhi, as opposed to what we saw earlier, is that even in affluent areas you see a lot of people coming down with Covid-19,” said Dr Shahid Jameel, a virologist and the director of the Trivedi School of Biosciences at Ashoka University.

Winter and pollution

Still, Delhi is not the only city with a segment of the population still susceptible. Other experts pointed to several more factors that may explain this third surge.

For one, they cited the cold weather in the city, which set in by late October. Cultures of viruses survive better in the cold, said Dr Jameel. “People in cooler weather tend to stay more indoors which increases the possibility of transmission from an infected person to a susceptible person,” he added.

The other aspect was pollution.

With more particulate matter, it stabilises the virus in the air, Dr Jameel said. “What the particulate matter does is increase inflammation in the nasal and throat areas, and lungs, and that makes you susceptible to more infections, not just Covid-19,” he said.

Delhi’s pollution levels have worsened over the months as cooler temperatures have set in. This, coupled with the burning of stubble in the neighbouring states of Punjab and Haryana, and a decreased wind speed have turned the national capital into a gas chamber.

Nearly 13% of the spike in Covid-19 cases in the beginning of November has been linked to air pollution, claims the Indian Medical Association.

Jameel said that other cities did not have the combination of various factors that Delhi has. “Punjab is also getting cooler but it is not seeing the surge,” he said. “Everything has come together in Delhi. No other city has the pollution levels that Delhi does. But the biggest cause is that people are not taking care.”

Other states

The combination of factors may explain why Delhi’s figures – around 7000 cases a day in the previous week – were so much higher than new cases elsewhere.

As of November 18, around 5,792 cases were recorded in Kerala, 2,732 cases were recorded in Maharashtra, 1,336 cases in Karnataka, 1,395 in Andhra Pradesh, 1,652 in Tamil Nadu, 1,420 in Uttar Pradesh, 948 cases in Telangana, 644 in Odisha and 601 cases in Bihar, according to the Press Information Bureau’s daily bulletin. The lowest numbers emerged from states like Assam and Jharkhand that recorded less than 300 cases on that day.

Another factor for this disparity between cities comes from the serological positivity rate noted in the serological surveys in various cities, said Dr Muliyil.

Serological surveys reveal how many people may have been infected with the novel coronavirus in an area but they do not show how many people are immune to the virus.

“This [seropositivity rate] is the percentage of people who have been infected,” Muliyil said. “It is the best indicator of how much the epidemic has spread.”

Delhi’s seropositivity rate is around 25.5%, according to the results of the fourth sero survey that was conducted in the beginning of November, Hindustan Times reported.

The fourth survey found a marginal increase from the results in the third survey in October that had recorded 25.1% sero positivity among Delhi residents. The second survey in September recorded 24.8%, while the first one in August recorded 29.1%.

Seropositivity surveys may show a drop in prevalence because antibodies are less detectable over time, though this does not mean those individuals are now vulnerable to the virus again.

In comparison to Delhi numberes, in Mumbai, the second sero survey conducted in October found the overall seropositivity rate to be 33.4%. This was a significant fall from 40%, the rate recorded in the first survey in June.

In Chennai, the first sero survey conducted in July showed an antibody prevalence of 21.5%. This figure increased in October in the second sero survey that recorded 32.3% of prevalence among the city’s population.

The seropositivity rates in Mumbai and Chennai are comparatively higher than the rates recorded in Delhi. A higher rate shows the presence of antibodies in a greater number of people which in turn explains a lower number of cases being recorded in these cities, Muliyil said.

“What I think is that Tamil Nadu will finish the epidemic first not because they did something smart but because the infection was spreading anyway,” he said.

Scramble for beds

Meanwhile, the increase in the number of cases in Delhi has burdened the health systems as several beds, including ICU beds, continue to remain occupied, said doctors in various city hospitals.

“We as a city are at the brink of being overwhelmed,” said Dr Sumit Ray, head of department for critical care medicine at Holy Family Hospital. Ray said he noticed a surge in cases in the middle of October.

Another doctor said that they too were overwhelmed with Covid-19 patients in the hospital. “Our ICU is full and we have created new beds for it as well as a semi-ICU,” said Dr Suranjit Chatterjee, a senior consultant for internal medicine at Apollo Hospital.

Chatterjee said that the general ward for Covid-19 patients was occupied as well. “We have been almost always full since navratri started,” he said, indicating that the surge began with the onset of the festive season.

Chatterjee added that the Covid-19 patients that were coming for treatment were “more serious than [the patients that came] before”. The complications had increased and patients were not being discharged easily because of their comorbidities, he said.

“Quite a few of our patients are those who have had kidney transplant, liver transplant, bone marrow transplant...they are coming back with Covid-19,” Chatterjee said. “Covid-19 in them is more tedious than in the normal population. They are having more respiratory issues. Their kidneys, liver are getting compromised.”

At least 88% of the ICU beds were occupied in 99 hospitals across Delhi, Indian Express reported on November 16. There were no ventilator beds in ICUs in 62 of these hospitals, including the ones that are run by the government, the report stated.

On Thursday, Delhi’s Health Minister Satyendar Jain said that the government had ordered 90 private hospitals to reserve 60% of the total beds for Covid-19 patients. This would add 2,644 more beds in private hospitals for the treatment of the virus, Jain said.

The lack of vacant ICU beds indicated the critical nature of the illness in Delhi’s patients, said doctors.

“Critically ill Covid-19 patients stay in the ICU for much longer than other critically ill patients,” said Ray. “So once they occupy a bed, it is gone for three to four weeks. It is a long stay. It does not get vacated easily.”

The outcomes of an overburdened system means that doctors have to first hold a triage to decide on the need for treatment in the hospital depending on the severity of the patient’s symptoms, he said. “The maximum cause of death is when the systems are overwhelmed and that is starting to happen in Delhi,” said Ray.

This reporting was supported by a grant from the Thakur Family Foundation. Thakur Family Foundation has not exercised any editorial control over the contents of this article.