Could rise in Covid cases across India be 4th wave, match IIT-K models?

On June 1, the number of fresh Covid-19 cases in Tamil Nadu spiked mildly from 98 to 139 after remaining below 100-mark for several weeks. Nothing alarming; isolated clusters and mild spikes in educational institutions and congested neighbourhoods, assured health officials. On June 7, the State had reported 144 fresh cases after hovering over 100 through the week. The Test Positivity Rates in Chennai and Chengalpattu have also spiked to 2.4%; Chennai reported a TPR of 4.6% on June 3, according to the State’s Covid-19 bulletin. A TPR of 5% or above indicates that the testing is inadequate and a lot more cases might go undetected. On Sunday (June 4), Health Minister Ma Subramanian announced that genome sequencing of 150 samples from the State resulted in detection of four cases of BA4 variant and five cases of BA5 variant.

In neighbouring Kerala, the situation is even more alarming. On Tuesday (June 8), the number of fresh cases surpassed the 2,000-mark with Ernakulam district reporting 662 cases, Thiruvananthapuram reporting 416 cases and Kottayam reporting 224 fresh cases indicating a clear rising trend, especially in thickly populated urban areas. For the past seven days, the state has been consistently reporting over 1,000 fresh Covid-19 cases.

This upward trend is similar in Maharashtra too where the number of fresh Covid-19 cases breached the 2000-mark on June 8 with the State reporting 2701 new cases of which 1765 patients are from Mumbai.

On Tuesday, Maharashtra reported 1881 new cases, a hike of 81% from the previous day.

Until the early hours of June 8, a total of 5,233 fresh Covid-19 cases had been reported across the country with Maharashtra and Kerala pushing the numbers as had been the case with all the previous three waves. Maharashtra, and Mumbai in particular, had been the first to report a major spike in cases which later replicated across the country. A communique from the union health ministry to five states, including Tamil Nadu, Maharashtra, Kerala, Karnataka and Telangana, on June 3 mentioned 2 districts in TN, 11 districts in Kerala, six districts in Maharashtra, and one in Karnataka where an increase in the cases have been reported. If these numbers indicate anything at all, a fourth wave of Covid-19 is very likely here.

In February this year, researchers at IIT Kanpur had put out a report titled ‘Fourth Wave of Covid-19 in India: Statistical Forecasting’ by the Department of Mathematics and Statistics in a preprint server Medrxiv which concluded that that the fourth wave of Covid-19 in India could arrive after 936 days from the initial data availability date, which is January 30, 2020. Therefore, the fourth wave was predicted to start from June 22, 2022, reaching its peak on August 23, 2022 and ending on October 24, 2022. ‘Moreover, the 99% confidence interval for the date, when the curve will reach the peak, is approximately from August 15, 2022 to August 31, 2022,’ the report stated. The study conducted in the Gaussian Distribution model compared the Covid-19 trends in Zimbabwe and India. A previous study by IIT Kanpur on the third Covid-19 wave was also very close to the actual rise and fall of cases due to the Omicron variant.

The fourth wave was predicted to start from June 22, 2022, reaching its peak on August 23, 2022 and ending on October 24, 2022.

However, the union health officials had claimed that the reports could be inaccurate on this occasion as a vast majority of adults in the country had been fully vaccinated and vulnerable groups had also been administered precaution doses. Minister of State for Health and Family Welfare Dr Bharati Pravin Pawar had told Rajya Sabha the study was an independent one conducted by IIT Kanpur’s Department of Mathematics and Statistics and conducted taking a relatively small actual sample and extrapolating the results to the entire population which, in turn, has failed to give reliable results for a large and diverse population.

Health experts have also pointed out that while there may be small surges, a major wave of Covid-19 cases was unlikely unless a new variant which could evade immunity more efficiently than all existing variants emerged and spread across the world. As on date, data put out by the World Health Organization on emerging and existing Coronavirus variants of concern across the world reveals that Omicron remains the dominant variant across the world with all the sub-lineages BA.1, BA.2, BA.3, BA.4, BA.5 and descendent lineages have taken over all previous variants. It also includes BA.1/BA.2 circulating recombinant forms such as XE.

A report put out by the UN News on April 13, 2022 claimed that Omicron BA.4 and BA.5 variants were not more severe or transmissible so far. WHO Director Tedros Adhanom Ghebreyesus said that they were following Omicron sub-lineages including BA.2, BA.4 and BA.5 and another recombinant detected, made up of BA.1 and BA.2, closely and that sub-lineages BA.4 and BA.5 were reported in a number of countries including South Africa and some European nations. “There are less than 200 sequences available so far and we haven’t seen any change in epidemiology or severity (for BA.4 and BA.5)”, she highlighted.

WHO’s lead scientist Dr. Soumiya Swaminathan, warned that sub-lineages and recombinants will continue to appear, and the world must continue investing in improved tools such as new vaccines. “We have to be prepared for the possibility that this virus can change so much that it might be able to evade existing immunity”, she told UN News.

As the WHO lead scientist suggested, a robust vaccination programme appears to be the best bet against the two new sub-variants BA.4 and BA.5 detected in TN last week and are likely behind the rise in fresh cases over the past few days.

According to a bulletin released by the TN health department on June 7, the State has so far administered 11,18,06,826 doses of Covid-19 vaccine with around 95% coverage for the first dose while the numbers for second dose are around 82%. Considering the rise in cases at Chennai and Chengalpattu, the state government has organized another mega vaccination camp in the coming days with around 1 lakh vaccination centers to ensure maximum coverage.

As several months have passed since the most active phase of the vaccination programme in the State, a booster dose which is pending for many of those who are eligible is the way to go in the battle against BA.4, BA.5 and any other emerging variants of Covid-19.