A child cries as a doctor wearing protective gear takes a swab from him to test for coronavirus disease (COVID-19) at a residential area in Ahmedabad, India, April 8, 2020. REUTERS/Amit Dave

India has recorded its 1,000th novel coronavirus death, but the head of a government think-tank said on Wednesday that its 1.3 billion people, strained from weeks of lockdown, were not experiencing the feared exponential surge in infections.

India has now reported 31,331 cases, including 1,007 deaths, according to figures from the Health Ministry. Prime Minister Narendra Modi must decide soon whether to extend the world’s biggest lockdown, now 40 days old, beyond May 3.

Meanwhile, officials pointed out that the number of COVID-19 hotspot districts in India as on Wednesday morning has come down to 129 from 170 a fortnight ago.

However, the number of infection-free districts or green zones too decreased from 325 to 307 in the same period. The number of non-hotspot districts, also known as orange zones, increased from 207 to 297, they said.

Red zones indicate infection hotspots, orange denotes some infection, while green indicates an area with no infections.

On April 15, the federal government had declared 170 districts across 25 states and Union Territories as coronavirus hotspots. Of these, 123 were hotspot districts with large outbreaks and 47 with clusters.

Health officials say the shutdown has prevented an explosive surge of infections that would have crippled India‘s modest health care system.

“Our analysis finds that the rate of growth in positive cases and fatalities has been consistently lower – linear but non-exponential,” said Amitabh Kant, chief executive of the government thinktank Niti Aayog.

Niti Aayog urged a phased exit from the shutdown, but the government has a difficult decision ahead.

The big cities of Delhi, Mumbai and Ahmedabad – which are also India‘s economic growth engines – top the list of cases and there are no signs of the pandemic abating there, Health Minister Harsh Vardhan said.

“When I see Delhi’s COVID-19 map, I see only red and orange colours which is extremely worrying.”

The government has already identified 15 districts in nine states, including Delhi, Maharashtra and Gujarat, as having “high case load”.

Of these, seven – Hyderabad (Telangana), Pune (Maharashtra), Jaipur (Rajasthan), Indore (Madhya Pradesh), Ahmedabad (Gujarat), Mumbai (Maharashtra) and Delhi show particularly high case volumes.

Other high case load places that are “critical” in the battle against COVID-19 include – Vadodara (Gujarat), Kurnool (Andhra Pradesh), Bhopal (Madhya Pradesh), Jodhpur (Rajasthan), Agra (Uttar Pradesh), Thane (Maharashtra), Chennai (Tamil Nadu) and Surat (Gujarat).

“These 15 districts are critical in our battle against COVID-19. Of them 7 show particularly high case volumes. India’s success in battling COVID-19 is dependent on them. We must aggressively monitor, contain, test, treat in these districts! We must win here,” Kant tweeted on Monday.

A senior health ministry official said the doubling time of coronavirus cases in India was three to 3.25 days before the nationwide lockdown was imposed on March 25 and now it is 10.2 to 10.9 days.