‘Too early to say that the second Covid-19 wave in India is dissipating’

While the rate of spread has seemingly slowed in a few states including Maharashtra the pandemic is still galloping in others Amid the second Covid19 surge vaccine shortages and talk of a third wave what answers do the numbers have for how Covid19 will behave in IndiaChennaibased researcher Dr Sitabhra Sinha a professor in the physics group of the Institute of Mathematical Sciences IMSc specialises in statistical analysis of epidemiological data mdash modelling the spread of infectious diseases through contact networks in a population His team has tracked Covid19 for over a year nowMiddaycom spoke to Sinha to understand the ongoing surge the missing links in data the role of vaccinations and his projections for the pandemicHere are the edited excerpts from the interviewWhat is the reason for the second surge in India When is it likely to slow and is there a likelihood of another surgeThe conditions conducive to another outbreak were existing for quite a while Very few individuals were adhering to any of the norms put in placemdash like wearing masks not crowding practising basic hygiene not spitting in the open mdash even though the pathogen had not gone away Possibly the fact that India fared relatively better than other countries during the first wave which I partly attribute to the early imposition of a national lockdown despite its quite problematic implementation which resulted in high social cost gave rise to a public perception that Indians are immune to the pathogenI would flag this complacency as the key factor that led to people not adhering to basic safety norms which could have prevented the second wave So the second wave as such is not surprisingIt was a disaster waiting to happen As to the actual causes that led to the outbreak happening in February that of course is a stochastic phenomenon mdash depending on several chance events coming together What is interesting is that unlike the first wave which broke in different parts of India at different times the second wave was much more coordinated across India The earliest was Punjab which showed the rise on February 9 followed by Maharashtra on February 12 and Madhya Pradesh on February 14 But after that the other states started showing the rise within a few days so that by early March most states had gotten into the second waveAs of April 24 there is a slight slowing down in the growth of active cases as characterised by R the effective reproduction number the average number of people infected by a single infected person which measures the rate at which the disease is spreading It has decreased from 131 estimated for the period between March 9 to April 21 to 116 for the period April 24 to April 30 This is possibly because Maharashtra has from April 24 actually shown a decrease in the number of active cases so that R is less than 1 Chhattisgarh has shown such a decreasing number of active cases even earlier from April 18 But what is really interesting is that I notice that several other states also show a decrease in their R although as the values are still greater than 1 the number of active cases will continue to increase However the states having the highest R at the moment havent shown this decrease so we still dont know whether this is the early sign of a flattening Its too early to say for sure that the wave is dissipatingYes a third wave is a distinct possibility if we cannot convince people to conform to basic norms such as wearing masksYour team observed a decline in the transmission rate in Maharashtra What can we make of thisFor Maharashtra R has gone down from 113 estimated for the period between April 7 ndash April 20 to 096 in the week starting April 24 If R is less than 1 it means each infected individual is on average being replaced by less than 1 person which means that the number of active cases is decreasing Thus the condition for an epidemic the number of active cases keeps increasing no longer holds in Maharashtra The same is true for Chhattisgarh which has had its R value of 156 estimated between March 10 April 16 decrease to 093 from April 18 onwards Of course these values are still close to 1 and liable to be reversed so that the number of active cases might again start increasing the next weeks will tell us if this is a sustained trend The measurement of R is done by statistically fitting exponentially growing or declining curve to the timeseries of the number of active casesCould the current decline in the number of cases in Maharashtra be linked to lockdown measuresTypically any change in R we see for Covid19 is related to events happening 10 14 days before that date So I would say if a particular event caused the decline in R in Maharashtra it occurred around April 10 April 14 How do vaccinations help in Covid containment and have you noted any changes in the transmission since vaccinations began hereIn general vaccinations are supposed to help contain an epidemic by reducing the number of susceptible individuals If a sufficiently high fraction of the population is vaccinated it also provides protection to unvaccinated individuals as the pathogen will not be able to find such individuals who are ldquohiddenrdquo in a crowd of vaccinated individualsThe critical fraction of the population that needs to be vaccinated so as to provide herd immunity is related to R0 Rnought the basic reproduction number which measures how quickly the disease spreads in a completely susceptible population For example for an epidemic with R0 of 2 at least 50 per cent of the population needs to be vaccinated to ensure that the epidemic doesnt occur I had estimated R0 for India to be close to 2 183 in factHowever Covid19 is quite complicated as even vaccinated individuals can get infected This means that the protection is only partial and a much larger fraction of the population mdash possibly even 100 per cent mdash needs to be vaccinated to ensure there are no epidemics As of now the number of people vaccinated is a few percent of the population of India and this will not make any practical difference to the rate at which the disease will spread Unsurprisingly the data shows no effect as yet of the vaccination What do we know about how damaging the variants of the virus areWe do not have data as to how many infections were caused by which variants so unfortunately its impossible to say what role the variants are playing Its complete speculation at this point with the data that we haveWhat has been Indiarsquos biggest challenge in dealing with Covid19 in the last one year What measures do you think India should be taking to prevent a worse wave in the futureThe challenge is balancing the social and economic needs of the population with the use of drastic measures to contain the epidemic such as lockdown I personally think that if people could have been convinced to adopt the much easier alternative of wearing masks in public and wearing it properly not under the nose or hanging from the chin and not congregating in high densities for various reasons religious or political we would not have needed to go to the extremely drastic option of lockdown which asymmetrically affects the economically weaker sections of the populationI think it should be clear by now that the most effective way to tackle Covid19 is simple nonpharmaceutical interventions such as convincing people to always wear masks in public in Japan for example many individuals wear masks in public for hygiene reasons mdash this was true even in preCovid times mdash so its just a matter of making it a social norm such that it becomes second nature to people ensuring that dense gatherings of people cannot happen and promoting basic hygiene like not spitting in public places not touching your face with unclean hands etc Vaccination is of course also important but even after vaccination people need to continue adhering to the above safety norms as the vaccine is not 100 per cent guarantee that someone will not get infected Apart from Maharashtra which are the other states showing an improvement and are there any states showing worrisome trendsAs I mentioned Chhattisgarh is another state which has had its R go less than 1 Among states which still have Rgt1 but for which R has decreased recently areKerala R decreased from 161 between April 13 ndash April 21 to 135 between April 24 ndash April 30Andhra Pradesh R decreased from 152 between March 11 ndash April 21 to 133 between April 24 ndash April 30Tamil Nadu R decreased from 140 between March 11 ndash April 21 to 109 between April 25 ndash April 30Bihar R decreased from 197 between March 29 ndash April 16 and 162 between April 16 ndash April 22 to 121 between April 24 ndash April 30Delhi R decreased from 160 between March 29 ndash April 20 to 110 between April 25 ndash April 28Telangana R decreased from 145 between April 10 ndash April 21 to 127 between April 24 ndash April 29Jharkhand R decreased from 150 between April 10 ndash April 21 to 121 between April 23 ndash April 30Odisha R decreased from 171 between March 31 ndash April 21 to 131 between April 23 ndash April 30It has been more than a year since the Covid outbreak How stressful has tracking its spread in India been for your team and what are your learningsIts been a humbling experience as we learnt that despite a lot of advances in epidemiological modeling techniques in recent decades the Covid19 pandemic still behaved in many ways that surprised us It has taught us that we are yet to know a lot about how epidemics evolve over time and space Is enough data being made available to data scientists to study the virus Would you like more numbers to be released by the government to help with future studyI use covid19indiaorg for obtaining data for my active cases I would really like to thank the team behind this website as they have been a godsend for scientists doing data analysis and modeling of Covid19 Of course we would love to have more data but without covid19indiaorg and other similar websites we wouldnt even have had that As I said there are many questions mdash like the role of variants mdash that we simply cant answer without the relevant data For this we need to identify the pathogen variant for each active case mdash which is pretty difficult to expect when hospitals are just getting overwhelmed trying to treat patients As a government public health official once told me during the 2009 Influenza H1N1 A pandemic do you want the doctors to treat patients or collect your data