India has reported 1,637 novel coronavirus, or COVID-19, cases with 45 deaths. The country saw its single biggest jump of 386 cases in the last 24 hours, with Delhi's Markaz Nizamuddin religious gathering contributing most of the cases.

Luv Aggarwal, Joint Secretary, Ministry of Health and Family Welfare, said on April 1 that the rise in cases doesn't represent a national trend. India still is one of very few countries that has reported the lowest number of cases versus its population.

According to Worldometer - India has one COVID-19 confirmed case and 0.03 deaths for every 1 million population while the global average is 113.2 cases and 5.7 deaths.

Bangladesh and Nepal, along with a number of countries in Africa, have comparable numbers to India. This led to many experts wondering why India has so few cases, despite having the world's second largest population and a weak healthcare system. To be sure - COVID-19 is still emerging, things could change in a matter of days. The numbers could look very different.

COVID-19 Vaccine Frequently Asked Questions View more How does a vaccine work? A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine. How many types of vaccines are there? There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine. What does it take to develop a vaccine of this kind? Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time. View more Show

India has only tested about 47,951 persons. Capacity utilisation across 126 Indian Council of Medical Research (ICMR) laboratories so far stands at 38 percent. We also have narrow testing, i.e. we test only those with travel history to affected areas or those who came into contact with a COVID-19 positive case.

ICMR expanded the criteria on March 20 to include symptomatic healthcare workers and family members who are taking care of COVID-19 positive patients. The narrow criteria helps in reducing the burden on the public healthcare system, but clearly India is not testing enough.

The symptoms of COVID-19 like cough, cold, fever and breathlessness are also very common. Most Indians self-medicate or do not see it as a concern. Unless there is popular mechanism to enable people to take self-assessment test on a daily basis, it's difficult to identify cases. These self-assessment tests should be in regional languages.

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India is imposing one of the world's largest lockdown, asking people to stay home and practice social distancing. The aim of the lockdown is to cut the possible human to human transmission and reduce the number of cases. These are too early days to judge the impact of the lockdown, but could still playout by helping in reducing number of cases.The Bacillus Calmette-Guerin (BCG) vaccine is now discussed as a possible reason for low COVID-19 cases in India. The vaccine is universally administered in India to protect against tuberculosis. Scientists in US, Europe and Australia have started studying whether BCG vaccine is of any help to protect people against COVID-19.

There are currently no vaccines against COVID-19. BCG is not universally administered in most regions, including US and Europe. Poland is the only European country that is still recommending use of BCG vaccine. "We are awaiting more scientific data on BCG's effectiveness against COVID-19. These studies are interesting because BCG provides protection against tuberculosis, which infect lungs like SARS-COV2" said GVJA Harshavardhan, Director, Viral Vaccines at Bharat Biotech.

While there is still no evidence that a rise in heat and humidity will slowdown the transmission of coronavirus, many experts feel it's still possible. "Most viruses will not be able to survive in temperatures beyond 45 degrees, that we know," said K Anand Kumar, Managing Director at Indian Immunologicals.

Kumar, a microbiologist himself, said Indian summer where temperatures soar beyond 45 degrees may act as deterrent against coronaviruses. IML owned by National Dairy Development Board (NDDB) produces vaccines for animals and humans.

There is a prevalent notion even among certain experts that the coronavirus strain that is circulating in India is a less virulent mutation. Gagandeep Kang, Director of the Translational Health Science and Technology Institute, however rejects this theory.

"The two shared Indian sequences are from two Wuhan returnees at the end of January. They are near identical to sequenced strains from Wuhan. Nothing special here, move on. Trust the right scientists," she tweeted on March 30. But still this theory is a popularly discussed one.