In an email interview with IANS, Prof. K. SrinathReddy, President, Public Health Foundation of India, said some evidencesuggests the novel coronavirus infection will wane in hot weather, like othercoronaviruses, but it is too early to conclude on it. He insisted herdprotection may develop over time. If we try to rush it through, we willinitially have a surge of cases which will overwhelm the health system andresult in many avoidable deaths.
Q: When do you think coronavirus cases will beginto decline, after two weeks May will begin; and under extremely hightemperature and dry conditions, how do you think this virus will respond?
A: The novel Corona virus causing Covid 19 is anew virus whose seasonality and response to hot humid weather is not yet fullyunderstood. Some evidence suggests that it will wane in hot weather, like othercorona viruses but that is still a conjecture. This view is still beingdebated.
Q: Some experts say we need to build herdimmunity, would not this put our health system under extreme pressure, and alsohave a cascading effect on patients visiting hospitals with other ailments?
A: Herd immunity, better called herd protection,may develop over time. If we try to rush it through, we will initially have asurge of cases which will overwhelm the health system and result in manyavoidable deaths. Even if you want to fill the sports stadium for the big game,you still have to regulate the flow at the entry gates to prevent a stampede.
Q: There is a huge demand for testing, would thishelp in containing the highly contagious viral infection?
A: Testing at higher rates would certainly helpto identify infected persons better. However, high rates of transmission havebeen reported even in the pre-symptomatic period. That makes testing decisionsdifficult, as it would be logistically impossible to test all asymptomaticpersons in the population. So, we have to use contact history and symptoms asthe testing criteria to begin with. Syndromic diagnosis, which is symptom baseddiagnosis of influenza like illness, also helps to isolate persons at home evenif testing is not widely available due to logistic constraints.
Q: Relapse of Covid-19, do you think is anotherbig challenge, in the absence of a vaccine?
A: We do not yet know whether these arereinfections, reactivations or false positive tests in the first instance. Wealso presently know how long the acquired immunity lasts. If true reinfectionsoccur, we have to manage them as we do fresh infections. Since the rate of�true reinfection’ is unknown, we cannot presently estimate how serious athreat it would be.
Q: Is there a straight jacket approach to counterthis deadly viral infection, if not, then what is the solution to combatCovid-19?
A: While public health principles are broadlycommon, specific strategies have to be customised to the country or state’spopulation characteristics (such as urban-rural population ratio and agestructure), health system capacity, availability of testing kits and competentlabs and adequate supply of personal protection equipment and intensive carecapacity in hospitals. Social distancing and personal hygiene practices areuniversal, while lockdown policies have varied between and within countries.
Q: District administrations across the countryare closely monitoring hotspots and clusters and conducting random surveys onlarge populations under these areas, will this strategy yield concrete results?
A: This is the ideal strategy in a large countrylike India. We need coordinated policy making at the central level,multi-sectoral planning and coordination at state level and decentralisedimplementation, with scope for context specific innovation and adaptability, atthe district level. Community engagements and multi-agency partnerships arealso best energised at the district level.
Q: What is a gold standard test for Covid-19,which is capable of highly accurate results and completely removing falsenegatives?
A: RT-PCR with collection from the throat throughswabs is currently the most advocated method. While it has been found to havevery high sensitivity in hospital testing conditions, the sensitivity may varyin field conditions depending how well the sample is collected. Bronchiallavage will give an even greater assurance of adequate virus samples but thatis not possible under field conditions and takes effort and time even inhospital settings.
Q: False positive result in asymptomatic persons,do you consider this a huge challenge?
A: False positive results become more frequent inpersons who have a low prior probability of infection, especially at highlevels of test sensitivity. An asymptomatic person, who has no travel historyto an affected country or a domestic hotspot location in the country or has nocontact history with an infected person, has a higher probability of testingfalse positive. However, this is presently considered as an acceptable risk bythe public health agencies as isolation of a person who �might be infected’ isconsidered necessary to break the chain of transmission. Even then,indiscriminate testing in the population should be avoided and clear criteriamust be established for suspect case or exposed person testing and for randomsample surveys in the population.