Covid-19 spread rate in Karnataka surges

The R0 for Covid-19 of both Karnataka and Bengaluru has crossed the value of 1, indicating that the virus is once again spreading. R0 or reproduction number, indicates the rate of spread.

The development comes even as Bengaluru city has been noting sharp increases in daily case numbers since Monday.

In the last two days, 965 new cases have been made public in the city (including 565 on Tuesday alone), with the curve likely to go up further in the days to come, according to experts.

These numbers represent 75 per cent of the state’s cases.

According to data from various scientists, Karnataka’s R0 crossed 1 on Christmas day and was 1.29 as of Monday. A senior official from the Health Department confirmed to DH that the R0 has crossed 1 in Karnataka prompting the state government to bring in measures like ‘night curfew’ to contain the spread. While the R0 had crossed 1 sporadically in previous weeks, there had not been a sustained high as is being seen now.

Meanwhile, Bengaluru’s reproduction number rose from 1.02 on December 22 to 1.11 as of Monday, according to calculations by Professor (Dr) Sitabhra Sinha of the Institute of Mathematical Sciences (IMSc) who has been conducting extensive R0 calculations for metropolises around the country.

Additional Professor (Dr) Ambarish Dutta, an epidemiologist with the Public Health Foundation of India (PHFI) said, “R0 is the number of cases that are expected to occur on average in a homogeneous population as a result of infection by a single individual,” he said, clarifying that an R0 of 1.29 means that one infected person is infecting at least one other person with a chance of infecting a second individual. If the R0 is 2, one infected person infects two other people.

The state’s peak R0 during the second wave was 1.91, on April 18.

Also read: Amid sudden spike in Covid cases, Govt writes to 8 states/UTs for 'immediate action'

“The increase in cases in urban areas across the country is likely due to Omicron even though genomic sequencing levels are too small to provide an accurate picture of which variants are driving the infection,” he added.

One clue that Omicron may be partly responsible is that similar, large gatherings of people for festivities during the Deepavali season did not produce a similar surge in cases.

“Evidence from other countries where genomic sequencing levels are adequate show Omicron’s hand in infections. In other countries beset by high levels of infection, the R0 is higher than 2,” Dr Dutta said.

Doubling Rate

Another scientist, who did not want to be named, pointed out Omicron’s case-doubling rate has reduced from three days a fortnight ago to two days currently and said that the number of cases in the country which are currently 974 could hit 2,000 by Sunday. He warned that places with at least 10 Omicron cases are just a few days from a surge.

Special Commissioner (Health) Dr Thrilok Chandra of the Bruhat Bengaluru Mahanagara Palike (BBMP) said that the city is still awaiting the genomic results from cluster cases which would better explain the driving force for these infections.

“The results are expected this week,” Dr Chandra said.

“We have all contingency measures in place if there is a further increase in cases. New Year’s restrictions have been approved. Surveillance, tracking and triaging activities are taking place. We are doing our best to track down every single case,” he added.

Check out the latest DH videos here: