Jara chronology samajhiye.

@shekhargupta cites an ICMR study of SARI patients, begun in mid-February, across some 50 hospitals in the country, to track the Covid-19 virus, which probably explains the decision to lockdown on 23rd March.

https://www.business-standard.com/article/opinion/shekhar-gupta-middle-path-medicine-120041100033_1.html

Read here.

First of all the ICMR sample of patients to track is deeply biased. Note they are tracking only SARI patients; those with “Severe Acute Respiratory Infection.”

Why is it biased?

The Covid-19 virus takes between 21 to 23 days to kill a patient.

From infection to day 1 to day 14, the viral infection is largely asymptomatic. Safe to say that the infected person doesn’t even know he has an infection in the first 10 days. Respiratory problems surface about 5 days before death.

So the ICMR sample left out a large subset of asymptomatic patients in its study.

But worse, emergence of SARI patients lag - repeat lag - actual infection by about 10 to 14 days.

So the sample is biased but also it is a lagging - instead of leading - indicator sample.

This 14 day lag, as we shall see is very crucial in the delayed decision to initiate lock down. This is Bourne out by another piece by @soutikBBC reporting on spread of the infection from Indore where there was clear community transmission from the first week of March itself.

. @soutikBBC story can be read here. It is crystal clear:

In early March, 40-year-old Ravi Dosi, a chest specialist in India, saw a baffling surge in patients with respiratory problems at outpatient clinics. https://www.bbc.com/news/world-asia-india-52242806

But back to @shekhargupta’s story in BS and the ICMR study with all its flaws.

From mid February to end February, ICMR was tracking only late stage symptomatic cases and tested 826 cases finding no infection.

SG doesn’t mention any date but says by the time 965 cases were tested, 2 positive cases had emerged. He mentions a date of 190th March later on but it makes no sense.

865 were tested in 15 days to end Feb. Going by averages, the first 2 positive cases would emerge by 2nd March

SG’s contention that by 19th march 2 positive cases had emerged to trigger lockdown points to a chronological mystery somewhere. My guess is the Govt delayed the decision to lockdown by a good 2 weeks after the alarm bell was sounded by ICMR around 2nd March.

Note @soutikBBC also doesn’t give an exact date but cites early March first week for a surge in SARI patients in Indore hospital’s OPD.

Why did Govt. delay the lockdown by two weeks? Fog of pandemic?

Mind there was a lot going on in the first 2 weeks of March.