Dat

Data | States which tested more in the initial days of the coronavirus outbreak found it easier to contain the spread

A lorry driver being screened by a health-care worker at Inchivila on the Kerala-Tamil Nadu border on Monday.  

Data from Indian States and a town in Italy show that ramping up testing in the initial days helps flatten the COVID-19 curve

How a region deals with the initial days of the COVID-19 outbreak determines its handling of the crisis.

Regions which ramped up testing in the first few days were able to flatten the curve early, while those which increased testing only later continued to record steep infection curves.

Lesson from Italy

A recent data blog published by the World Bank compares the case curve in the town of Vo in Italy (3,305 residents) with the case curve in the Diamond Princess cruise ship (3,711 travellers).

Vo tested almost all its residents after registering its first few cases, while the ship tested only those who showed symptoms. In the first round of testing, Vo detected more cases than the ship. In the second round, the number of new cases in Vo dropped.

Viewing in app? Click to see table.

image/svg+xml *Infection rate per 100 people = (100 x total infected) / total population Parameter Vo Ship Population 3,305 3,711 Cases (1 st test) 87 10 Infection rate* (1 st test) 2.6 0.3 Cases (final test) 6 712 Infection rate (final test) 0.2 19.2

Table appears incomplete? Click to remove AMP mode.

In the ship, asymptomatic persons spread the infection to others causing a surge in cases in the second round of testing. Notably, while Vo initially quarantined only those who were infected, the ship quarantined most of its passengers.

Therefore, while lockdowns and quarantines help slow the spread, ramping up testing in the initial days flattens the curve.

How States tested

The chart plots the seven-day rolling average (median) of COVID-19 tests conducted per million population since the 10th case in select States where such data were available.

Viewing in app? Click to see chart.

image/svg+xml 0510152025303540455055 Days since the 1st case 1 2 5 10 20 50 100 200 500 1,000 2,000 Median calc 2000 500 100 20 5 1 0 10 20 30 40 50 Bihar Kerala W.B. M.P. T.N. Maharashtra Avg. no. of tests per million Days since the 10 th case In the first 24 days after identifying the initial infections, Kerala's test rates were much higher than others West Bengal's and Bihar's responses were poor initially and continue to be so TN had a sluggish start, but it recovered well Though they initially responded slower than Kerala, Tamil Nadu and Maharashtra ramped up testing in the later days of the outbreak and even surpassed Kerala's test rate
 

Impact on case curve

The chart plots the infection rate per crore^ people for every 10 days since the 10th case. Kerala is the only State which recorded a drop in the infection rate. In most States, the infection rate is increasing in varying degrees.

Viewing in app? Click to see chart.

image/svg+xml 500 100 20 5 1 1 to 10 11 to 20 21 to 30 31 to 40 41 to 50 Bihar Kerala W.B. M.P. T.N. Maharashtra Infection rate per crore people Days since the 10 th case Despite Maharashtra's and T.N.'s late ramping up of tests, infection rates in these States continue to increase. This indicates the importance of ramping up testing in the initial days of the outbreak Infection rates in Bihar and W.B. are still low as these States continue to conduct fewer tests than other States
 

^Infection rate per crore = (1 crore x total infected) / total population

Source: World Bank, State health ministries.

Why you should pay for quality journalism - Click to know more

Next Story