Why Bengaluru is seeing a surge in Covid-19 cases

In the last five days, there has been a concerning increase in the number of Covid-19 cases in Karnataka, especially in Bengaluru Urban, which experts say is due to a cocktail of more social-distancing violations, interstate travellers and possibly even the entry of new variants of the novel coronavirus.

Since March 10, there has been a surge of cases during which the state has registered 4,231 new cases. Such numbers have not been seen since the start of the new year. According to the data, 65.3% of the state's cases (or 2,764) have been in Bengaluru Urban.

A deeper look shows that the largest increases over the last seven days have been in the city’s South Zone (548 cases), followed by Bommanahalli (457) and East (383).

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While it was noted that social-distancing violations have generally been high, officials could not clearly nail down what was causing the surge, except that increased testing was netting more cases, some of whom are interstate travellers.

Epidemiologist Dr Giridhar Babu pointed out that surges only begin if the number of cases rise above a threshold level — and that this rise only happens if there are a critical number of susceptible persons.

"Many susceptible people are traveling from outside due to the opening up of literally every place, many people who were protected erstwhile will also get infected. There is a possibility of newer variants transmitting also, which are more infectious than the earlier strain," Dr Babu pointed out.

He added that the number of super spreader events in closed spaces such as colleges, marriages, cinemas and functions was increasing gradually.

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In Bommanahalli, this is clearly evident, said the Zonal Joint Commissioner, M Ramakrishna. "At nearly every cluster, there have been large numbers of people with a travel history. But we expect the numbers to come down as border screening intensifies," he said.

He added that increased testing at schools, slums and other high-population locations was netting a high number of cases. Official data shows that Uttarahalli and HSR Layout have the highest concentrations of cases in the last seven days.

In the South Zone, Joint Commissioner Veerabhadra Swamy attributed the testing of people working in the food and hospitality sector for netting a higher number of cases.