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Ventilation,Facial Protection Best Safeguards Against Airborne Covid


New Delhi: In a recently published report in The Lancet stated SARS-CoV-2, the virus that causes Covid-19, is an airborne pathogen. The paper written by six experts from the US, the UK, and Canada, say that the evidence supporting airborne transmission is overwhelming, and evidence supporting large droplet transmission is almost non-existent.

Speaking to IANS Professor Srinath Reddy, president Public Health Foundation of India said: “While the virus can spread by air even in the open, the flow of air currents will not allow large viral clouds to form and hang around while such clouds can form easily and waft around slowly in closed spaces.” He stressed on wearing proper mask and eye protection to prevent from virus entering through nose, mouth or eyes, and ventilation a key ally in keeping the viral load low. Excerpts from the interview:

Q: A report recently published in The Lancet stated SARS-CoV-2, is an airborne pathogen, isn’t it worrying? If Covid is airborne, wouldn’t it require an overhaul of modification of established Covid-19 safety protocols.

A: I believe that both droplet and aerosol modes of transmission are important. Droplet transmission occurs in close proximity in open or closed spaces while airborne infection is more likely as viral clouds form in closed rooms. While the virus can spread by air even in the open, the flow of air currents will not allow large viral clouds to form and hang around while such clouds can form easily and waft around slowly in closed spaces. In either case, wearing a proper mask and eye protection is likely to prevent the virus from entering through nose, mouth or eyes. Ventilation is a key ally in keeping the viral load low.

Q: The Lancet paper said, “Long-range transmission of SARS-CoV-2 between people in adjacent rooms but never in each other’s presence has been documented in quarantine hotels.” If this report is accepted by the broad scientific community, then it will have major implications on how people fight Covid-19?

A: Viral clouds forming in closed buildings can drift between rooms. Ventilation and facial protection are still the best safeguards. We will need better quality masks or double masking. Indoor ventilation systems have to be improved. Open cross ventilation is ideal.

Q: With infectious variants emerging, which can escape the immunity and vaccines, even after a year into the Covid pandemic. Do you think there is a possibility of a third wave, or things would finally begin to settle after this second wave?

A: It is difficult to predict the levels of infectivity and vaccine escape future variants will have. We must hope that the inactivated virus vaccine (Covaxin), which presents a bigger platter of viral antigens for invoking an immune response than vaccines which focus only on the spike protein, will have less threat of vaccine escape from variants which develop spike protein mutations. Whether there will be a third wave of serious infections will depend on how fast we strengthen our public health system and how widely we vaccinate.

Q: According to genome sequencing data “double mutant” has become the most common variant. However, patterns have not emerged to establish that the double mutant is driving spike in cases amid the on-going second wave. Do you think double mutant will become a dominant variant similar to Kent variant?

A: It is possible that a variant which exhibits greater infectivity than the original wild virus will become dominant over time. Given different variants operating now in different parts of India, it is possible that may see patterns of regional dominance by different variants in different parts of the country. The emerging patterns will also depend on how effectively we can contain transmission from now on, within and between states.

Q: In the first wave, the cases peaked in September, almost one lakh every day for weeks, but later it declined. Today, there are more than two lakh cases every day. Is it the peak of the second wave and when will it begin to decline?

A: This time the pandemic resurfaced in a fully open society, with high levels of mobility and crowded events. Last time the unlocking was in stages and some restrictions continued for several months. So, the surge soared swiftly. How long it will last will not merely depend on models of how the virus behaves but on how we behave. If we can all wear the right kind of masks the right way whenever away from home and crowded events are curbed with resolve, we can see a downward trend in a few weeks. Otherwise, this wave can get stretched over some months.

Q: Today, the government claims to have a fairly good idea about which mutated variant is prevalent where, but all of them are increasing. Isn’t it a worrying situation?

A: A batsman like Rahul Dravid, with a sound ‘Wall’ like defence, can face a left arm bowler with as much confidence as he faces a right arm bowler. If we wear the right kind of facial protection the right way and avoid super spreader events involving crowds, we can block both the wild virus and its variants from entering our body. If we expose ourselves and play carelessly, we can be bowled leg stump or off stump. We have to determinedly play the right kind of defence- for some months to come.

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