Herd immunity has to be acquired over time: Dr K Srinath Reddy

The measures taken so far were intended to slow down the transmission, even if the chain is not completely snapped countrywide.

Published: 16th April 2020 08:30 AM  |   Last Updated: 16th April 2020 08:44 AM   |  A+A-

Dr K Srinath Reddy

Express News Service

To avoid high death toll, India needs to contain the spread from high case density zones to low case density zones, Dr K Srinath Reddy, president of the Public Health Foundation of India and member of the National Task Force on Covid-19 management, tells Sumi Sukanya Dutta.

Q. The government’s approach so far has largely been to contain the Covid-19 outbreak through lockdown and social distancing. How do you think the outbreak pattern has been in India? Can we avoid going the US, Italy or Spain way? Is there an estimate on when could the outbreak peak in India?
The measures taken so far were intended to slow down the transmission, even if the chain is not completely snapped countrywide. It appears from the hospital admission records that there has been no surge. Given the lag time between viral entry into the body and death, this cannot entirely be attributed to the impact of lockdown. However, the rate of doubling of new cases has slowed down despite the number of tests increasing. These are positive signs. If this trend continues, we can expect the epidemic to peak by April-end. To avoid going the way of the high-toll countries, we need to continue social distancing and contain the spread from high case density zones to low case density zones.

Q. The government has reposed a lot of faith in anti-malarial drug hydroxychloroquine. But evidence of its efficacy against the disease seems to be mixed. Are there new therapies we could see being tried in India in coming days?
All drugs being tried out for treatment of Covid-19 are under investigation as no definitive evidence of benefit in clinical outcomes is as yet available. Several clinical trials are underway testing the impact of hydroxychloroquine, antiviral drugs used in other conditions and passive immunity through infusion of plasma from recovered patients. The results of these trials will provide the needed evidence. Till then, clinicians can use their best judgment.

Q. What are the tools and systems India needs to fight the outbreak? Are we prepared enough?
We need to step up our community based surveillance, combining symptom based syndromic surveillance and lab testing to the extent resources permit. We need to provide PPE to all healthcare providers and support staff. For this, we must quickly ramp up domestic production...We need to expand the health workforce with addition of retirees, trainees and auxiliaries. We need a nationally coordinated policy, state level planning and district level implementation.

Q. There is growing evidence from some countries that SARS CoV2 could be re-infecting some people or getting reactivated again in same hosts? If true, won’t that be a big worry?
We do not know what parts of these are due to re-infection, reactivation or inaccurate test results. We do not know how long acquired immunity lasts with this virus. We also do not know if the clinical impact is less severe in these patients. We’ll have to deal with this by further intensifying our public health response and augmenting clinical care systems.

Q. Some epidemiologists in India have suggested that herd immunity against the virus, with or without vaccine, could be only way to stop the storm? What are your views on that?
Herd immunity arises when a large proportion of the population, between 60-70%, is infected, recovers, frees itself of the virus and thereby stops transmission to others. Actually, it is herd protection, because the uninfected person has no acquired immunity. If such a person goes to another community where only 20-30% have been infected, he/she becomes vulnerable, too. Herd immunity will have to be acquired over time rather than as a sudden exposure of large numbers to the virus. That will trigger a rush to hospitals which will be overwhelmed.

Q. The ICMR is now allowing all symptomatic people in hotspots to be tested as well but some experts feel random testing among both symptomatic and asymptomatic people could be crucial to assess the extent of the outbreak. Your views?
Random sampling is needed. We  must get district wise profiles through such testing. Testing in asymptomatic cases is fraught with a higher risk of false positives but we must still perform such surveys to profile each district. This must be supplemented with community based syndromic surveillance and hospital based statistics. We need a three-dimensional picture.


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