NEW DELHI - A resurgence of Covid-19 cases in Maharashtra and a few other states in India has had a sobering impact on the country, after a steady decline in infections over the past five months.

The resurgence has yet to upset the nation's overall downward trend in cases.

Maharashtra, which has seen seen an increase in infections over the past two weeks, registered 5,210 fresh cases on Monday (Feb 22).

The increase has led to a ban on all religious, social and cultural programmes since Monday. The Vidarbha region was among the worst-affected area in the state with lockdown instituted in Amaravati. Other cities such as Pune have also recorded a rise in cases.

Maharashtra along with Kerala, which has also bucked the national downward trend, make up 75 per cent of active cases in India.

Three other states - Madhya Pradesh, Chhattisgarh and Punjab - as well as Jammu in Kashmir have similarly seen cases start to go up in what officials said was a cause for concern.

Epidemiologists believe the coronavirus is now being transmitted in sections of the population in areas less affected previously.

But they said that it was unlikely India would suffer a return to the peak when 97,000 new cases were being registered a day in September.

"The chances of that (returning to Covid peak) happening is very remote. There is no need to panic. It will come down like it came down in (the capital city) Delhi, which had a second and third wave," said epidemiologist Jayaprakash Muliyil.

"Once it (the virus) stabilises, there will occasionally be some groups, which have isolated themselves carefully and are starting to go out, getting infected. Such outbreaks will happen."

An apartment complex in the southern city of Bengaluru last week became a containment zone after 103 of its residents tested positive after two parties.

India, the world's second most populous country with 1.3 billion people, has been among the worst affected in the world with the total number of those infected at 11 million and 156,302 deaths.

There are no definitive answers on why infection numbers have come down.

Epidemiologist and health experts have pointed to everything from herd immunity to a stringent lockdown two months after the virus was first detected in the country. Others have argued greater immunity in South Asia and a young population.

Officials have for now ruled out the the possibility of new variations from the UK and South Africa for the current spike.

"There is no reason to believe these strains are responsible for the upsurge that we are seeing in some districts of Maharashtra and Kerala," said Dr Vinod K. Paul, a member of Niti Aayog (National Institute of Transforming India) who is a paediatrician by training.

"We are still vulnerable. This virus is still around and it surprises us. These are warning signals to us. The virus likes parties and large gatherings," he added.

Experts say the number of cases is likely to fluctuate until the population is vaccinated.

"India's experience so far is that it has been an urban phenomenon. It didn't spread through the length of and breadth of country as many had predicted. But there will be pools of susceptible people in rural areas and in districts which have so far been relatively untouched," said Professor Rajib Dasgupta, chairman of the centre for social medicine and community health at the Jawaharlal Nehru University.

"There will be ups and downs. The rural population is still relatively untouched as sero-prevalence surveys show. That is a huge pool of population where we can expect this to smoulder. We can expect this periodic surge. Whether the whole country will see a surge only time will tell."