States that ramped up testing have recorded a low positivity rate, reaffirming that tracing, testing and isolating is the only way to contain the virus spread even as India’s covid-19 cases touched 7.4 lakh on Wednesday.
Telangana has recorded the highest test positivity rate (TPR) of 28.27%. A high TPR indicates that testing is inadequate, and new chains of community transmission are being ignored. Only 19 of the 35 states and union territories in India meet the World Health Organisation (WHO) standards of a TPR under 5%.
“Unless testing is ramped up, we cannot contain the virus. A low TPR means testing is sufficient and there is robust surveillance. A high TPR indicates that states are not tracing enough people and checking them," says Dr Pramukh Natesh, surgeon and public health analyst.
An analysis based on Union health ministry data and Google community mobility reports shows that states with a high TPR had a low testing percentage. Maharashtra, which has the country’s highest covid cases, records a TPR of 21.76%. The state conducts just 9,246 tests per million people.
Delhi is a good example of ramping up testing and lowering the TPR. It’s rate has fallen from 36.9% in the second week of June to 10.45% on Wednesday.
The national average of TPR is 9.57%. Five states—Telangana (28.27%), Maharashtra (21.76%), Tamil Nadu (11.71%), Delhi (10.45%) and Karnataka (9.7%)—have a poor testing record and a hight TPR.
For a population of 8.3 crore and having the second highest number of positive cases, Tamil Nadu tests 18,157 per million population. Himachal Pradesh has the lowest TPR and for a population of 75 lakh, the state did 12,235 tests per million.
“We cannot lower our guard on testing. Aggressive testing and isolating are the only way to break the chain of transmission," said Dr Nagendra Swamy, Founder Chairman, Medisync Health Management Services.
Another critical measure to know the rate of spread is the effective reproduction number (RT). This checks the rate of spread or number of people infected from a single case. WHO recommends an RT below one to conclude that the outbreak is under control.
Barring four states and one union territory—Delhi, Uttarakhand, Manipur, Himachal Pradesh and Ladakh—all others have a score above one.
India tests only 7,637 persons per million, which is inadequate. The number of labs authorised to test must be increased, which will automatically reduce the waiting period for results as well as reduce the pile-up of cases, said Dr Swamy.