Rise in Covid cases, R number in some states worrying, but premature to declare third wave: scientists

PTI, Aug 4, 2021, 4:19 PM IST

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New Delhi: The rise in fresh Covid cases and the effective reproduction number – an indication of how fast an infection spreads — in many states are worrying but don’t panic. Instead, mask up and get vaccinated, say, experts, stressing that it is too early to declare the beginning of a new wave. In fact, it could be that the second wave is not over, said several scientists who have been closely monitoring India’s Covid graph and have noted the surge in a few pockets.

In the northeast, for instance, cases have certainly not gone down to the low levels that are being seen in Delhi and other northern states, observed Gautam Menon, professor, Departments of Physics and Biology at Ashoka University in Haryana. ”In that sense, we are likely seeing a continuation of the second wave rather than the initiation of a new Covid wave distinct from the previous one,” he explained. On Wednesday, India recorded 42,625 fresh Covid cases with a daily positivity rate of 2.31 percent and a weekly one of 2.36 percent.

India’s Covid situation is seemingly under control. However, 13 states/union territories recorded a surge in coronavirus infections last week with Kerala reporting half of India’s daily new cases. Last week, Kerala reported 1.4 lakh new COVID-19 cases, around 20,000 more than the previous week.

In the week ended August 1, Delhi, Himachal Pradesh, Uttarakhand, Mizoram, J&K, Sikkim, and Karnataka also witnessed a rise in cases.

With the government warning that the pandemic is “still raging”, there is also an increase in India’s effective reproduction number (R) which represents the number of susceptible people one Covid positive person may infect.

A recent analysis by researchers at the Institute of Mathematical Sciences, Chennai, found that the effective R number in India has crossed 1 for the first time since May 7.

The government on Tuesday also said the R-value is more than one in eight states and UTs, which is a cause of concern.

Researcher Sitabhra Sinha, who has been tracking the value of R since the beginning of the pandemic, is alarmed that this rise is not driven by the increase in cases in any particular region but seems to be resulting from several states having R values greater than 1 roughly around the same time.

“Apart from Kerala which has had R above 1 for more than a month and the northeastern states where the second wave has not yet subsided after beginning in July, we saw in the past week R increase above 1 in Karnataka, Himachal Pradesh, and Haryana, and possibly in Uttarakhand,” Sinha, from the Institute of Mathematical Sciences, told PTI.

“The cities of Chennai, Kolkata, Bengaluru, and Delhi also are showing R above 1. This suggests a rise in the active cases that is coordinated across widely scattered regions which would be hard to contain,” he added.

The need of the hour is to press the accelerator on Covid protocols.

“We need to be prepared but not overtly panic. It is time people mask up and get vaccinated,” Delhi-based physician-epidemiologist and health systems expert Chandrakant Lahariya told PTI, adding that the numbers clearly indicated the need to be cautious. He noted that COVID-19 cases are mostly being reported from states that had succeeded or avoided transmission earlier. Some of this, he said, is attributable to the high transmissibility of the Delta variant.

“We should not be looking at the proportion contributed by a state of the total new cases reported in India. That is not very helpful as we end up comparing the states with better reporting systems with states with weak disease surveillance systems,” the public health expert said. The wave or cycle is of academic significance only. If cases are rising, it does not matter whether that is a continuation of the second wave or the start of the next wave, he said.

“The interventions have to be very similar.” Scientist Gautam Menon agreed that while it is too early to declare the third wave, the surge in cases is certainly worrying.

“The next few weeks will be critical to see whether the rise in case numbers, currently confined to the south and northeast of India, will spread across other parts of the country where cases have been declining for the past month,” Menon told PTI.

Explaining the rise in cases, Menon said the spike in Kerala can be traced to the relatively low levels of seropositivity there, indicating that much of the state has not undergone a prior infection and should therefore be susceptible.

“From the few serosurveys that exist for the northeast, a similar situation should hold there,” he added.

The results of the fourth national serosurvey by the ICMR have shown that nearly 79 percent of samples from Madhya Pradesh had antibodies against coronavirus, while the seroprevalence was the lowest in Kerala at about 44 percent.

Sanjeev Galande, dean of the School of Natural Sciences, Shiv Nadar University, Delhi-NCR, was also of the view that it is early to predict whether this is the beginning of the next wave.

“The national weekly average hasn’t altered significantly. A small increase is seen in a few states. It is too early to predict whether this is indeed the beginning of the next wave,” Galande told PTI.

He noted that although the second wave had not completely subsided, the R-value had decreased below 1 in most of the states, and the total number of new cases had come down to 30,000 by July 19, indicating a steady decline.

“Due to regional surges, now the daily new cases in India have crossed the 40,000 mark,” said Galante, adding, however, that this is a marginal increase compared to what happened in the month of May.

Menon hoped that what may prevent an India-wide wave is simply the fact that a substantial fraction of people in populous northern states, including Uttar Pradesh and Bihar, have already been infected in the first two waves of the disease.

“This will very likely slow the progress of the disease and should lead to a wave that is blunted in extent compared to the devastating second wave. The current levels of vaccination, although limited, will also help,” he explained.

Galande cautioned that other states have to be vigilant and prepare for a rise in the number of cases.