Litmus test: Next 15 days will chart path of city’s Covid curve

FIGHTING COVID-19

Litmus test: Next 15 days will chart path of city’s Covid curve

Numbers Falling, But Experts Caution Against Premature Celebration

TIMES NEWS NETWORK

11.07.2020

The effects of the relaxation in lockdown norms since Monday – an increase in crowds in public places – may have its effect from Saturday. If in the next 15 days the number of cases and deaths do not increase, Chennai can say it has flattened the curve, say epidemiologists.

All the virus needs is a host, says infectious diseases expert Dr V Ramasubramanian. “We are giving it lots of hosts when we crowd shops and fail to wear masks,” he said.

Covid-19 symptoms – fever, cough, cold, breathlessness, loss or smell/ taste and diarrhoea – usually start between the 5th and 10th day of exposure. “It takes another 2-3 days for them to get to the doctor and receive the test results. This would mean we are likely to see an uptick in the number of cases over the next two weeks,” he said. The incubation period – the period between exposure to an infection and the appearance of the first symptoms – is 14 days.

It’s still unclear if the virus is spread via tiny droplets, or aerosols, or through larger droplets expelled when an infected person sneezes or coughs. “We know the virus can stay aloft for hours in tiny droplets in stagnant air and infect people as they inhale. This risk is highest in crowded indoor spaces with poor ventilation. So, if we have a symptomatic or presymptomatic person they can trigger outbreaks. The chance of it happening is bigger when rules of pandemic are not followed,” says infectious diseases expert Dr Subramanian Swaminathan.

Fresh cases in Chennai have been steadily dropping – from 2,206 on July 1 to 1205 on Friday – although adjoining districts such as Chengalpet, Kancheepuram and Tiruvallur have been seeing an up and down variation. On July 1, the three districts together had 4,67 cases, 629 on July 3, and 410 on June 7. But for the next two days, they together had 600 new cases and on Friday had 522.

Many ministers and officials have been tweeting that the city has flattened the curve, but public health experts warn it may be too early to say. Senior virologist Dr T Jacob John of Christian Medical College said the state is climbing towards the peak – when the same number of cases is seen for at least a week. “This week, if there is no increase Chennai can rejoice. This may happen if the surveillance during lockdown is good. If fever clinics are doing their jobs and testing numbers are high we will still be able to isolate positive cases and stop the spread,” he said.

National Institute of Epidemiology deputy director Dr Prabhdeep Kaur said flattening the curve will depend on doubling time, daily cases and deaths and positivity rate. “Each one of these factors shows the infection is down. During this time, the number of tests being done should not decrease,” she said.

We are giving Covid-19 lots of hosts when we crowd shops and fail to wear masks

Dr V Ramasubramanian | INFECTIOUS DISEASES EXPERT