Rising R Values
There is a worrying trend in the COVID situation in India, of late. The R number in the last week of August shot up to 1.17, as reported by scientists working at the Institute of Mathematical Sciences (IMS), Chennai. As a comparison, let's look at the R-value just a week earlier. It was just 0.89 during Aug. 14-17, 2021. Dr Sitabhra Sinha, lead author of the latest report, says that "Not only is it greater than one, it is much higher than the last time there was a scare of a third wave (it was 1.03 at that time)."
Why is R number so important. It signifies the number of people an infected person can transmit the disease (in this case COVID-19) to, on an average. A value of 1 means that an infected person, on an average, is transmitting the disease to 1 uninfected individual. If R dips below 1, the pandemic will gradually taper off. However, if R is greater than 1, the number of infected people would increasing in each round and the disease will be in the epidemic phase (that is, surging ahead fast). In that case, the outbreak may go out of control and there may be a new wave of the pandemic.
Let's say the R number is 1.1. This roughly means 100 infected persons could transmit the disease to 110 people (in the first round), with correspondingly higher numbers of infected persons in further rounds. The R-value denotes how fast an infection is spreading, a slight rise in the value may indicate an imminent upward trend in the wave again! India's R number rise may be attributed to surge in Covid-19 cases in some states. As per data released by IMS, R-value of Kerala is 1.33 (HT, Sep 4, 2021). Some other states with high R numbers are: Mizoram (1.36), J & K (1.25), Andhra Pradesh (1.09) and Maharashtra (1.06).
During the peak of the 2nd wave (Mar-May, 2021), the R-value was 1.37. During May 15-June 26, the value declined to 0.78. But it gradually started rising: it was 0.88 (June 20-July 7), 0.95 (July 3-22), 0.96 (July 24-27). The threshold value of 1 was crossed for the first time after the 2nd wave during July 27-31 (R-value, 1.03). The R number then started waning again: 0.92 (Aug. 6-9), then rose again: 0.99 (Aug. 12-14). The number dipped to 0.89 (Aug. 14-17) but abruptly jumped to 1.17 in the last week of August 2021.
Although we may not be fully certain, this shifting trend may be a sign on an impending third wave of COVID-19 in India!
Possible Third Wave
The possible imminence of a third wave is the likely outcome of several factors: rise of new variants, adherence to Covid-appropriate behaviour (CAB), level of susceptible population, rate of vaccinations, and rigour of pandemic control authorities. Ironically, except the first one, all other factors are partly or fully under our control. Still, we have failed to contain the pandemic even after more than one and half years. Possibly, human behaviour is more whimsical than that of the viruses!
Let's reflect on some of these factors. First, the emergence of new variants. The WHO has recently dubbed a new coronavirus variant, Mu variant, as a 'variant of concern (VOI)." It's technically designated as B.1.621. It was first detected in Columbia in January 2021 and has since spread to about 39 countries. It has acquired mutations that enable it to partly escape the immune response triggered by the vaccines. WHO has dubbed it as a VOI. There are now 5 variants of interest now: Eta, Iota, Kappa, Lambda and Mu. If Mu acquires more changes that make it more harmful, it may become a 'variant of concern (VOC)." At present, there are 4 VOC: alpha (B.1.1.7), beta (B.1.351), gamma (P.1) and delta (B.1.617.2). The Mu variant now accounts for 39% of new COVID cases in Columbia; luckily, there are as yet no recorded Mu cases in India.
The delta variant has given rise to 13 sub-lineages: AY.1-AY.12 and AY.3.1. AY.1 is what is often referred to as Delta Plus (technically, B.1.617.2.1). Recently, one of these sub-lineages AY.12 has been found in some states in India including Uttarakhand (News 18, Aug. 31, 2021). Whether this or other sub-lineages of the Delta variant will cause a third wave in India remains to be seen.
Another variant called C.1.2 has been found in South Africa and some other countries. Preliminary reports claim that it could be more infectious and may evade the protection provided by vaccines. It has not been categorized yet as either a VOI or VOC. It was first dtected in South Africa in May 2021 has since spread to China, DRC, Mauritius, England, New Zealand, Portugal, and Switzerland etc. So far, it has not been found in India. It possibly has the fastest mutation rates among the variants (41.8 mutations per year). This strain could be more transmissible and has the potential to escape immune protection (IT, Aug. 30, 2021).
Another concerning strain called the Epsilon variant has been detected in Pakistan (www.india.com/; last accessed, Sep. 4, 2021). The most worrisome aspect is that this strain is possibly resistant to all the available vaccines. This varaint was first detected in California in 2020 and has now landed in our backyard! This variant is technically called CAL.20C. It has been found in 34 nations besides the US. It's possibly as transmissible as the Delta variant. It triggered the 4th Covid wave in Pakistan.
This or a sub-lineage of Delta could possibly trigger a third wave in India. But the severity or timing of the wave is subject to how strictly we follow the CAB and how soon we scale up double jabbing the majority of the population in India and Manipur. Let's remember that the virus needs a susceptible host, irrespective of the social status of the host. Therefore, we must strictly avoid crowding of any kind: religious, cultural, recreational, or political etc. We cannot allow certain kinds of crowding while banning other types. We got two powerful weapons against the variants: masks and vaccines. Let's note that, amidst the raging variants, 1 dose isn't effective; so, the target has to be, to fully vaccinate (double jabbing) 70-80% of the population as soon as possible.
