India’s rural districts, home to nearly 74% of India’s population, accounted for 65% of all Covid-19 tests conducted in August, and 55% of new cases reported that month.
Urban districts, on the other hand, are home to 14% of the population and accounted for nearly 22% of all tests conducted in August, with 28% of the cases reported that month coming from them.
The government this week released in Parliament data on the number of Covid-19 tests conducted in each of India’s 734 districts in August. This is the first time that district-level data on testing from across the country was made public.
Rural areas have a disproportionately lower share of tests, and an even lower share of cases
This analysis has divided India’s districts into three large groups – urban districts (less than 40% rural population), mixed districts (40% to 60% rural population) and rural districts (more than 60% rural population). The proportion of the rural population is based on the 2011 Census (the latest data available). Data on the number of cases has been sourced from How India Lives (11 revenue districts of Delhi have been taken as one single unit because the Delhi government does not release a district-wise breakup of confirmed infections). The number of tests conducted per million people in rural districts was 14,880, compared with 26,115 tests per million in urban districts.
Lower positivity rate indicates that rural areas are better covered by Covid-19 testing
Nationally, about 8% tests in August came out positive. But this figure was 10.5% in urban areas and 6.9% in rural areas. Both were higher than what is recommended by the World Health Organisation, which says the positivity rate from a region that has a comprehensive testing programme should be at or below 5% for at least two weeks before it can be considered that the outbreak is under control.
To be sure, the government has not given a breakup of tests by method. A Reverse Transcription-Polymerase Chain Reaction (or RT-PCR) test, seen as the gold standard in Covid-19 testing, tends to result in a higher positivity rate because the other common method, the rapid antigen test, may throw up false negatives for people who are infected with a low viral load. The government said on August 4 that about a quarter of all Covid-19 tests across the country were rapid antigen tests. A greater share of rapid antigen tests in a region may lead to a lower positivity rate there. Anecdotally, Bihar and Uttar Pradesh, which account for 18% of all rural districts in the country, depend heavily on antigen tests. Some predominantly urban areas, such as Delhi, also use a disproportionate number of antigen tests.
Urban districts have 2.7 times as many cases per million residents than in rural districts
In August, rural areas reported 1,023 confirmed cases per million people compared to 2,736 confirmed cases per million people in urban areas. While it is possible that the infection spreads at a slower rate in the rural areas because of the low population density (people per square kilometre) there, it is equally possible that the results have been skewed by states such as Uttar Pradesh and Bihar (which have a large proportion of rural population) depending largely on inaccurate antigen tests. To be sure, the population density metric ought to be read with care. For example, Bihar’s Vaishali district (more than 80% rural population) has a population density of 2,164, more than Haryana’s Gurugram (1,267), which has 31% rural population. The positivity rate in Vaishali was 2.8% compared to 4.3% in Gurugram — but this again, may be because of Bihar’s dependance on antigen tests which lower the positivity rate.
Massive variance across India’s districts in positivity rate, often within states
332 districts reported at least 1,000 infections in August. Of them, the positivity rate was below 5% in 96 districts and more than 30% in six districts. Maharashtra’s Nandurbar and Ratnagiri districts had the highest positivity rate (48% and 43% respectively) even though both are rural districts. Similarly, not all urban areas have a high positivity rate. Delhi, for example, had a positivity rate of 7%.
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