Corona Second Wave — How to Tackle it ?
Tags: Corona

The B.1.1.7 variant engulfed UK in no time and this video clearly shows how this happened over a small period of time

The best estimates shows that the B117 variant can be 50% more infectious and also 60% more deadlier. Now if no measures are undertaken, then many researchers are anticipating that the Ro( transmission rates ) can be as high as 4.3. That is every one single individual can infect 4 to 5 more individuals. However with various restrictions in place, the Ro of the virus is still in controllable levels and needs to the brought down to less than 1, where people stop spreading the virus.

Whatever people talk about the lockdowns in India? Lockdowns controlled transmissions in India for a very long time and it is one single reason why India had one of the lowest per capita death rates among all the nations infected by Covid. The number of infections were very less in India. Contrary to what is concluded from the seroprevalence surveys which are based on few samples ( not even random), i’m of the opinion that the infection rates in India were very low and timely intervention of masks along with strict social distancing norms kept the Ro lower in the country. So it is important to note that India had large number of susceptibles who could be infected by this virus.

The adaptive evolution of virulence: a review of theoretical predictions and empirical tests (nih.gov)

Refer to the above paper, which clearly brings the trade off between virulence and transmission. As per the above paper, there is a direct trade off between virulence and transmission. In the initial phases of pandemic, the virulence will be higher and hence the transmission increases and also the death rates. The excerpts from this is enclosed below:

However, a number of authors have studied how virulence evolves during the epidemic, rather than endemic, phase of epidemiological dynamics (Lenski and May, 1994; Day and Proulx, 2004; Day and Gandon, 2007; Bull and Ebert, 2008; Bolker et al. 2010). The consensus from this theoretical work is that, under a transmission–virulence trade-off, virulence will be higher during the early stages of an epidemic, when the abundance of susceptible hosts is high, and will evolve to lower levels as the endemic equilibrium is reached. Put another way, during an epidemic, the parasite population will be dominated by more virulent parasites than would be expected on the basis of the standard theoretical approach. This has important implications for understanding the dynamics of emerging infectious disease (Berngruber et al. 2013).

So, if any one is talking that India is reaching the end of the covid waves, then looking at the virulence and the transmission rates, it can be easily observed that India has lot more susceptible and hence the virulence is higher. So we are still in the initial phases of pandemic with large number of susceptibles who would be exposed with virulence and higher mortality rates. So it is very important for aggressive action so that vulnerables are not exposed to higher virulence of these viruses resulting in higher mortality rates. So the trend is clear wherever the number of suspectibles are higher, there will higher virulent forms like B.1.1.7 that will emerge and try to dominate. In India, we are seeing two variants right now B.1.1.7 and B.1.167 trying to dominate the species. But from other countries experience, if B.1.167 dominates B.1.1.7 then it will be surely more transmissible and more lethal than B.1.1.7. Notwithstanding the presence of B.1.167, a double mutant, even B.1.1.7 is a highly virulent virus which has a Ro of 4.3 which can spread very fast.

The detailed report on B.1.1.7 released by NIH, UK can be accessed here.

Investigation of novel SARS-CoV-2 variant: Variant of Concern 202012/01 (publishing.service.gov.uk)

Assessing transmissibility of SARS-CoV-2 lineage B.1.1.7 in England | Nature

Some important observations from this are given below

[1]With time, B.1.1.7 or B.1.167 will become the dominant strain.

The above image shows SGFT ( B117) dominating with time

[2] One good news is that stricter lockdowns, social distancing, school closures worked in controlling B.1.1.7 in UK. Initially piecemeal restrictions were placed and the virus kept rising even during November 2020 to December 2020(third week). Only after severe lockdowns were placed, the reproductive number started coming down.

If you look at India’s and UK R number, it is very clear that India is passing the R number now and the transmission rate is just increasing inspite of many restrictions placed all over the country. The samething happened in UK between Nov 16,2020 and Jan 5 2021. Only after severe lockdowns were placed combined with a vaccine doses, the cases have started coming down significantly all over UK.

So although the virus spreads faster, but there are now some empirical evidences that lockdowns can contain this virus. There is a double advantage of lockdown, it can contain non-variants and also variants and thus results in lower transmission levels.

[3] The secondary attack rates in contacts identified through national contract tracing were 30 to 40% higher for the variants and most of them were house hold contacts. So in spite of lockdowns the virus can spread through house hold infection route.

[4]B.1.1.7 case fatality rate are higher and they have greater risk of mortality. Refer this blog below which clearly shows that the risk of mortality is higher by 64%. So if this driving the growth in India, then its a matter of concern.

Infections with ‘U.K. Variant’ B.1.1.7 Have Greater Risk of Mortality — NIH Director’s Blog

[5] The Transmission is surely higher and one unique think about this is when the transmission is faster and the economy is open, then more number of asymptomatic people would be carrying the virus. Many estimate that the proportion of asymptomatic carriers in B.1.1.7 may be way larger than the earlier one and this is one of the primary reason for increased house hold attack rate. We have large number of so called healthy people infecting others.

Although this sounds crazy, practically a healthy person ( he/she thinks ) will never know that they will spreading the virus and hence it is almost impossible to see who is spreading the virus in the entire group. As a result since the virus is more infectious, it spreads faster among the young and then gradually moves into the vulnerables to kill the later. So if asymptomatic patients are driving transmission, then it is serious matter of concern, since under the present restrictions, there is no restrictions placed on the movement of the young population. Since you cant find out who is transmitting, it is almost impossible to test, trace, treat. So this strategy fails to some extend now.

India is surely at a stage which is precarious. A latest study by Financial Times published on 23rd April 2021 stated that many states are witnessing doubling rates of less than 7 days and most Indian states will see huge spikes in the coming days.

Doubling Rates for various states. States which are showing faster doubling rates should watch out and take corrective actions. Maharashtra has already reached the peak, but it needs to handle the huge influx of critically ill patients.( Source: ‘It is much worse this time’: India’s devastating second wave | Financial Times (ft.com) )

It also reported that there is significant underreporting of deaths and states that the deaths are probably 5x or 10x times more than what is reported.

Analysis of reported deaths and creamtorium deaths. So clearly India is already seeing large number of deaths and this juncture quick action and aggressive policy is the need of the hour.