New Delhi, The 21-day nationwide lockdown gives India an opportunity to flatten the new coronavirus curve, especially if widespread testing is carried out during this period -- the absence of which will increase chances of resurgence of cases after the lockdown period is over, leading health experts warned on Thursday.

Total number of coronavirus cases in the country rose to 649 from 606 a day before, the Ministry of Health and Family Welfare said on Thursday. The number of cases were just about half four days ago.

"The number of cases doubling in a few days is not actually a surprise because these people acquired infection sometime in the past before the lockdown. They are developing symptoms and coming to light now," Professor Vivekanand Jha, Executive Director at The George Institute for Global Health in India told IANS.

In fact, the number of cases are likely to continue to increase in the next one or two weeks at least.

"Because the incubation period is two weeks, if someone got infected, for example the day before yesterday, that patient may develop symptoms even after two weeks," Jha informed.

"The lockdown will obviously flatten the curve somewhat, but there is a risk of resurgence of the disease. Or the curve will go up again unless in the meantime we strengthen our healthcare system, both in terms of providing more testing, but also in terms of augmenting our hospitals so that if cases appear later on, the hospitals will be able to provide appropriate care to those people," he emphasised.

There are 29 private laboratory chains, accredited by the Indian Council of Medical Research (ICMR) for conducting tests for novel coronavirus, Joint Secretary of Health Ministry Lav Agarwal told reporters on Wednesday.

These labs have 16,000 collection centres across the country, where at least 12,000 tests can be conducted per day.

Besides private labs, there are 119 government laboratories approved by ICMR, of which 104 are operational for testing COVID-19 and 15 are in the process of being functional according to ICMR data put out on March 24.

Mugdha Tapdiya, Associate Consultant, Internal Medicine, Fortis Hospital Vasant Kunj in New Delhi also agreed that "only lockdown is not enough" to flatten the coronavirus curve in India.

"We have to lead by the examples of South Korea and Japan, where they have managed to flatten the curve with wider testing and lockdown with self-discipline. There are lots of minimally symptomatic or asymptomatic people (without a history of travel) at this time who are sitting at home with the elder family members," Tapdiya said.

"Once they become sick they will never be tested because there is no travel history which is a huge mistake. Test, treat, isolate should be the norm. Larger bounce back will be staring at us once the lock down is over if we do not test more and allow positive people to spread undiagnosed infection in community," Tapdiya added.

According to the revised strategy of testing for COVID-19 infection, issued by the Ministry of Health and Family Welfare last week, all asymptomatic individuals who have undertaken international travel in the last 14 days, should stay in home quarantine for at least 14 days.

They should be tested only if they become symptomatic (fever, cough, difficulty in breathing). Besides, all family members living with a confirmed case should be home quarantined.

The revised strategy further stated that all symptomatic contacts of laboratory confirmed cases will be tested, all symptomatic health care workers will also be tested. All hospitalised patients with severe acute respiratory Illness (fever and cough and/or shortness of breath) will also be tested for novel coronavirus.

What is needed now is more effective isolation of infected people and continued education and communication to raise awareness among people, said Navin Kumar, Head of Clinical Microbiology & Infection Prevention, Manipal Hospitals, Dwarka, New Delhi.

Meanwhile, according to the Medical Technology Association of India (MTaI), an association of research-based medical technology companies, in the current situation, quick movement of medical equipment is paramount for timely diagnosis, monitoring and treatment of patients suffering from COVID-19 and other critical ailments.

However, manufacturers and distributors of crucial medical devices are facing several logistical challenges due to restrictions on inbound passenger flights and as well as movement of vehicles between cities and states, it added.

The lockdown is majorly affecting courier agencies like Bluedart, SafeExpress, and FedEx which are not allowed to move freely even while carrying medical devices. If the logjam continues, hospitals could face an acute scarcity of medical devices very soon, MTaI said in a statement on Thursday.