The novel coronavirus has swept the globe and caused a pandemic that's become one of humanity's gravest health crises. The virus wrecking havoc across the world is a new type of coronavirus that originated in China late last year.

Scientists are still trying to understand how the novel coronavirus -- officially named Sars-CoV-2 -- functions, infects and spreads. And so, we're sure you have a number of questions of the novel coronavirus and Covid-19, the disease caused by the virus.

In two exclusive interviews with India Today TV's Rajdeep Sardesai, the director of Delhi's All India Institute of Medical Sciences, Dr Randeep Guleria answers all the questions regarding Covid-19 and what can be done to safeguard oneself from the infection. Use the links below to navigate:

1. Who should get tested for novel coronavirus?

2. How long does it take for symptoms to appear?

3. Should everyone be wearing masks?

4. Should those with asthma wear a mask?

5. If a colleague gets infected, what should be done?

6. Is it safe to visit hospitals with Covid-19 patients?

7. Will summer or humidity kill the novel coronavirus?

8. Should malls and restaurants be avoided?

9. Can a person cured of novel coronavirus get it again?

10. Is social distancing the best way to tackle this disease in a country like India?

11. Do yoga and pranayam build immunity against Covid-19?

12. Are blood donors screened for novel coronavirus?

13. Will sipping hot water kill the virus?

14. Are hand sanitisers better than soap?

15. Will cleaning doorknobs keep novel coronavirus away?

16. How long does the virus survive on surfaces?

17. Will a cough droplet that falls on one's clothes infect someone?

18. Should non -vegetarian food be avoided?

19. What precautions should pregnant women take?

20. Any precautions before taking a flight?

21. What underlying conditions can prove risky?

22. Will Covid-19 outbreak worsen before it ends?

23. Are Indians more immune to coronavirus than others?

24. Does smoking affect chances of recovery?

25. What type of a mask is preferred?

26. At what point should one get tested for Covid-19?

27. Can an asymptomatic person spread the virus?

28. Should senior citizens with mild cough also get tested?

29. Is fecal transmission of coronavirus possible?

30. How long does it take to recover from Covid-19?

31. Why are youngsters getting infected more in India?

32. Does hydroxychloroquine work?

33. Do vitamin-supplements build immunity against coronavirus?

34. Does staying in the sun between 10 am and 11 am build immunity against Covid-19?

35. What should patients awaiting surgeries do?

36. Is it safe to buy newspapers?

37. Are takeaway pizzas and food delivery safe?

38. Is it safe to receive packages from areas with Covid-19 cases?

39. Is the virus less virulent in countries with BCG immunisation?

40. Why do fatality rates vary in different countries?

41. Are blood tests as effective as oral swabs?

42. Can rapid testing help in containing the outbreak?

43. Have we managed to avoid community spread?

44. Coronavirus in India is less virulent than in the rest of the world?

Watch: Coronavirus FAQs | Part 1

Dr Guleria: Even if you have a fever and a severe cough, or a sore throat, you still need not get tested as of now unless you fit in two criteria. The first criteria are whether you have travelled abroad in the last 14 days, especially to a country where an outbreak of novel coronavirus is happening or you have come in close contact with a laboratory-confirmed case of Covid-19.

Dr Guleria: This is what we call the incubation period. It usually takes between 2-7 days but it varies up to 14 days. Rarely, it has been reported that sometimes it can take even longer but in most patients, within 5-7 days symptoms will start to appear in the form of fever, cough and sore throat.

Dr Guleria: Everyone need not wear a mask. It is important to understand that if you have a cough and cold, you should wear a mask so that you don't transmit the infection to others. If you are a healthcare worker looking after patients, it's worthwhile to wear a mask. Otherwise, a common person going out for day-to-day work or is at home or even going out for some time need not wear a mask, it does not protect you. Sometimes it can be harmful because you might end up touching your face to re-adjust the mask and end up transmitting disease from an infected surface on to your face using your hands.

Editor's note: Dr Guleria's answer on wearing masks is from a Q&A session conducted before countries started modifying their advisories on masks. Based on evidence that masks can stop an asymptomatic carrier of Covid-19 from unwittingly spreading the virus, several countries including India are now recommending or even mandating that people wear homemade masks or face covers while stepping out of their homes. This would, theoretically, help reduce the risk of large-scale outbreaks of the novel coronavirus. The fact remains that there is not much scientific evidence that masks protect the wearer from the novel coronavirus.

Dr Guleria: Those with asthma need not necessarily wear masks. However, they need to wash their hands regularly and maintain social distancing apart from avoiding crowded places.

Editor's note: Dr Guleria's answer on wearing masks is from a Q&A session conducted before countries started modifying their advisories on masks. Based on evidence that masks can stop an asymptomatic carrier of Covid-19 from unwittingly spreading the virus, several countries including India are now recommending or even mandating that people wear homemade masks or face covers while stepping out of their homes. This would, theoretically, help reduce the risk of large-scale outbreaks of the novel coronavirus. The fact remains that there is not much scientific evidence that masks protect the wearer from the novel coronavirus.

Dr Guleria: If you have come in contact who is infected, it is important to start the process of self-quarantine because you could get the infection or end up transmitting it.

Editor's note: The Ministry of Health and Family Welfare has urged anyone who has knowledge of prior contact with a confirmed Covid-19 patient to come forward and inform local healthcare authorities as a precaution.

Dr Guleria: It's safe to visit hospitals because patients infected with novel coronavirus are being kept in isolation wards. However, one must not visit the hospital at this time unless it is absolutely necessary. Routine healthcare visits should be postponed.

Dr Guleria: My feeling is that it would not. It might decrease the transmissibility of the virus. We still have cases in tropical countries like Singapore and Thailand. A large number of us spend a lot of time inside the house or shopping malls, areas which are air-conditioned. And here the temperature is low and there is crowding. If one person has the infection and he is coughing, the person can spread the virus.

Dr Guleria: As of now, till we are not sure about the resolution of this pandemic, I would say that we should take to the process of social distancing.

Dr Guleria: This is a viral infection unlike swine flu or H1N1 but once you are exposed to the infection, there is a chance of getting it again. Once you get the infection, there are antibodies produced in the body which protect you against subsequent infection or make it less severe. If you get exposed to novel coronavirus, later on, it will be a mild infection.

Dr Guleria: The UK is following a similar model where it is allowing the infection to spread to the community but protect the high-risk groups (elderly, diabetic, hypertension, heart or respiratory issues). Since the mortality in the younger age group is very low, you may have a large number of individuals who may get the infection and cause herd immunity and therefore, you might not have a very large outbreak.

However, young people can still transmit the disease to the elderly which is why herd community can create problems in a country like India.

Dr Guleria: There is no evidence to support that yoga or pranayam or ayurvedic or homoeopathic drugs are effective as far as treatment of Covid-19 is concerned.

Dr Guleria: Blood donors are not tested for novel coronavirus. It is important to understand that this is a novel coronavirus which was not there as far as humans are concerned as of last year. It is an animal virus that mutated and jumped species and became a human virus and it also developed the ability to sustain human-human spread. But the chances of it being significantly present in the blood are low; it is mainly in the upper-respiratory fact. Blood testing is not required for healthy people as of now.

Dr Guleria: Neither sipping hot water nor consumption of alcohol will kill the virus. Alcohol-based sanitisers kill the virus on your hands but once in your throat, the virus infects the cells and alcohol cannot help there.

Dr Guleria: If you can use soap with water, it is a better thing. One uses soap more thoroughly and it helps clear the virus in between the fingers and under the nails. If you do not have soap, use hand sanitiser but clean your hands thoroughly and regularly.

Dr Guleria: One of the ways the novel coronavirus spreads is through droplet infection. Droplet means that it is in the air for some time and people who come in close contact with someone who has the infection get infected. But these droplets also settle on surfaces and touching these surfaces can lead to infection. If someone infected with novel coronavirus touches a doorknob with his hands, the infection will settle on the doorknob for a few hours and it is a good idea to clean it.

Dr Guleria: Depends on the surface. Some data suggests that it can survive on cardboard for a few hours or other surfaces which are metal-based and especially if the temperature is low and the humidity is high, it may even survive 6-8 hours. That is why it is important to regularly wash hours.

Dr Guleria: If you touch the cough droplet on your clothes with your hands and then touch your face, it can lead to infection. Touching one's face should be avoided. The cough droplet cannot reach one's respiratory tract by itself.

Dr Guleria: There is no evidence right now. Eating well-cooked non-vegetarian food outside or at home poses no risk of coronavirus.

Dr Guleria: There is no data suggesting that like swine flu, pregnant woman are at a higher risk. Pregnant women should avoid crowded areas.

Dr Guleria: One should avoid non-essential travel. If you are travelling, regular hand washing is important.

Dr Guleria: Whatever data we have from China suggests that some groups are at a higher risk. These include elderly; those above the age of 60 have a more severe infection. People with co-morbidities such as diabetes, hypertension, chronic heart or respiratory diseases are also at a higher risk and need to be extra careful.

Dr Guleria: Global trends suggest that the infection is still on the rise and has not reached a plateau. The number of cases is rising all over the world. There will be rise over the next few weeks until that plateau is reached and then we will see a downward trend as can be seen in China and South Korea.

Dr Guleria: There is no data to suggest this.

Dr Guleria: Smoking does decrease the respiratory defence mechanism and therefore, the recovery does slow down. I would advise people to either decrease or quit smoking.

Dr Guleria: The N-95 and triple-aid masks are for healthcare workers operating in hospitals and infected areas. The self-made face cover does not have a very strong filter but it helps in reducing the transmission. If everyone covers their face with self-made masks, including people who have a very mild coronavirus infection, the droplets of water will not jump from host to host.

Dr Guleria: The symptoms of coronavirus are very non-specific. If I have a little bit of fever and get tested, it would be a waste of resources. It is important to get people with severe symptoms and healthcare workers tested because we do not want them to contract the infection. The elderly and those with co-morbid conditions are at a higher risk, diagnosing them and treating them is important.

Dr Guleria: Initial data pointed out that this was unlikely but some data suggests that some percentage of individuals may be having no symptoms but they could still be spreading the disease, especially in the younger age group and that has emerged in the last few weeks.

Dr Guleria: There is no need for that. However, senior citizens must try and stay at home and wash their hands frequently. Solution is not testing, the solution is preventing not getting the infection.

Dr Guleria: Studies suggest that there can be a fecal-oral transmission. It is unlikely to be a major area of transmission but this is still an area of research.

Dr Guleria: It depends on what type of illness you have. According to the breakup that we have, 80 per cent of individuals will have a mild or asymptomatic disease and they will recover on their own within 5-7 days. You have another 15 per cent who have a border disease, may need hospitalisation and they will recover within 10-15 days. The remaining 5 per cent who have a severe disease will be in the ICU, may need ventilator support and they may take about three weeks to recover.

Dr Guleria: India has a younger population as compared to other countries and the degree of mobility is much higher and that's why the transmission is much higher in youngsters. Mortality is directly linked to age.

Dr Guleria: We had initially one study from France. More recently, another study has come up from China which suggests that giving hydroxychloroquine to Covid-19 patients can decrease the viral load, decreasing the days of admission in hospital required. So, there is some evidence although it is limited. We need more data to establish a clear link.

Dr Guleria: Some data suggests that Vitamin-C may be helpful. For the other vitamins, there is not much data. There is no harm in taking it but it cannot be said for sure that it may help.

Dr Guleria: There is no data suggesting that staying in the sun or warmer temperature helps against the virus. The virus is inside the body and body temperature won't decrease by staying in the sun. Also, we are having another outbreak in Singapore where the weather is much warmer and tropical. Similarly with southern India where the temperature is not helping in the reduction of transmission.

Watch: Coronavirus FAQs | Part 2

Dr Guleria: In this era of Covid-19, we should also focus on non-coronavirus patients. We should also see once what can be done about surgeries once the lockdown is lifted. Emergency surgeries are being done, dialysis is also being done. We are also working on teleconsultation. It's important for people with co-morbid conditions. A person on hemodialysis should be getting it as per schedule.

Dr Guleria: It is safe to buy newspapers because it is not like the person delivering the newspaper is infected because if he was infected, the delivery person would have symptoms and those who are concerned can see how they can clean their newspapers thoroughly. The chance of transmission through newspapers is very little.

There are issues about how long can the virus survive on surfaces. It can survive on newspapers, cardboard boxes, and metal cans for some hours and even on plastics and steel surfaces for a longer period of time. If you are using these boxes or getting them from the market, take time and clean it properly with an antiseptic solution.

Dr Guleria: Pizza itself is cooked at a very high temperature. It will kill any bacteria or virus that is there. If you are still concerned, clean the outer surfaces which may have been touched by people with cloth dipped in an anti-septic or alcohol-based wash. That will provide enough safety.

Dr Guleria: Chances of transmission of the coronavirus through packages are quite low. If you are really concerned, clean the package from outside with an anti-septic solution.

Dr Guleria: There is this hypothesis which suggests that those in countries with BCG immunisation, their immune system are a bit more resilient due to the vaccines. However, it is too early to say whether BCG can prevent Covid-19 because it is meant to counter micro-bacterial tuberculosis.

Dr Guleria: Fatality rates depend on the age of the population and the number of cases per day. Flattening the curve by means of the lockdown has led to a reduction of mortality.

Dr Guleria: A nasal swab is meant to pick up the virus in your throat or the posterior part of your nose, therefore, it tells you whether the virus is there and you are infected or not. The blood test does not pick up the virus. If you have early symptoms, the blood test will be negative for Covid-19. It looks at anti-bodies your body produces once you have had the infection and these anti-bodies will remain positive for months.

If I was infected with coronavirus a month ago but I'm all right now and decide to get an antibody test done, my anti-body will still be positive although I have no infection.

Dr Guleria: The rapid test will give us information about how the Covid-19 infection is panning out in different parts of the country. If the rapid test suggests that a lot of people in one region test positive, then one can say that there is still ongoing infection in that region. If you do rapid tests in a region where a lot of people are symptomatic but most of them test negative, it can be said that their symptoms are not related to coronavirus but common flu.

Dr Guleria: Extensive community spread is not there but there are definitely hotspots that have developed where there is suspicion about limited community spread and we need to really see how to clamp down on this because this should not further progress. If we can aggressively prevent localised spread which has occurred in hotspots then we can prevent community spread.

Dr Guleria: Not too much data suggests that the virus is behaving differently in different parts of the world but I do believe that we have to look at the virus more critically, find out whether it has mutated and are we getting a strain that is less virulent.

The lockdown has helped because the rise in the number of cases is not rapid in other countries. Data coming in after April 12 will give us a clear picture of whether or not it is wise to partially lift the lockdown.

(The first part of this interview was aired on March 17, 2020)

(The second part of this interview was aired on April 4, 2020)