The population of West Bengal is three times that of Assam. Yet, as of April 20, the number of swab samples that two states had tested to detect Covid-19 among their residents were almost comparable. West Bengal had tested 5,469 samples while Assam only marginally fewer at 5,112.

Normalised for population, these numbers look even starker: Assam had tested 163 people per million people, while the number for West Bengal stood at 60. The national testing average is 317 people per million, as of April 20.

Even by India’s relatively low testing numbers compared to other countries, West Bengal lags – and by a far margin. It has tested the least among all the large states. For instance, neighbouring Bihar, a state of comparable size and population, had tested twice as much till April 20. Yet, Bihar had reported 96 cases till April 20, while Bengal had 339 cases and 12 deaths.

This is the other reason West Bengal stands out: it has a high positivity rate. For every 16 samples the state has tested, it has found a positive case. The corresponding number for India as a whole is 26.

“When your testing rate is low and your positivity rate is high, it means you are missing out positives,” said Giridhar R Babu, professor and head of life course epidemiology at the Public Health Foundation of India.

What explains this? After all, the testing guidelines are centrally set by the Indian Council of Medical Research.

Poor contact tracing

Doctors and health officials Scroll.in spoke to pointed to several reasons for West Bengal’s low testing numbers. For starters, the Trinamool Congress government was not following the ICMR’s guidelines strictly enough, said Manas Gumta, a doctor who works at a tertiary hospital in Kolkata and is the general secretary of an association of the government doctors in the state. Even high-risk healthcare workers were not being tested as ICMR guidelines mandated, Gumta alleged.

“The people of Bengal are sitting upon a volcano at the verge of explosion at any moment,” he wrote in a letter to the government on behalf of his association on April 14. “The apparent less number [of Covid-19 cases] that is reflected here is due to the low number of tests performed.”

As far as the high positivity rate is concerned, a district health official in the state said it was the result of inadequate contact tracing. According to the ICMR’s guidelines, all contacts of laboratory-confirmed tests need to be screened. While the low-risk contacts are to be home-quarantined and tested only if they show symptoms, high-risk contacts such as immediate family members and closely attending healthcare workers have to be mandatorily tested irrespective of clinical manifestations.

West Bengal, the official alleged, was not doing that robustly enough. “Contact tracing is not done properly, so very few people are actually tested,” said the doctor, who requested anonymity fearing reprisal.

Another leading epidemiologist closely tracking the situation in the state agreed. “They are not finding enough cases because they are not doing enough contact tracing,” said the epidemiologist, who did not want to be identified since he was wary of a backlash from the government. “If you compare the number of contacts they are tracing per patient to other states, you will know what Bengal is doing.”

Another reason for low testing numbers was the sub-optimal utilisation of laboratory resources, claimed Gumta. “Only one of the 10 approved testing facilities is optimally functioning,” said Gumta. “That is the one in the Institute of Post-Graduate Medical Education and Research. All the other centres are practically lying idle.”

The epidemiologist said the lacklustre state response was not entirely surprising. “How can you expect the state that does not report dengue properly to report Covid properly?” he said. In the past, West Bengal has been accused of fudging data related to dengue outbreaks in the state.

A vegetable vendor next to the figure of a demon holding placards to raise awareness about the Covid-19 pandemic. Credit: Dibyangshu Sarkar/AFP

‘The numbers are constantly improving’

State officials, though, said the reality was more complex and there had been delays on account of factors beyond the government’s control.

“There were faulty kits being given to us by NICED,” said a senior health official who asked not to be identified by name. The National Institute of Cholera and Enteric Disease is a research organisation that functions under the Central government. “We had to run tests twice to get conclusive results, so it was taking 72 hours for test results to come,” the official said.

On Monday, NICED admitted some of the kits it had supplied to the Bengal government were defective. The next day, it said it would withdraw the consignment of defective testing kits and replace them with kits assembled by the Pune-based National Institute of Virology.

In any case, the health official said the state was gradually ramping up its testing and increasing the number of testing facilities. “Yesterday, we did 713 RT-PCR tests in one day,” he said. “The numbers are constantly improving.”

The official also dismissed allegations of the state’s contact tracing process not being robust enough. “The total number of people who have been kept in institutional quarantine so far is 13,560 and 9,598 have already been released after having done their 14 or 28 days,” he said. “These figures cannot come if you are not doing robust contact tracing and quarantining.”

Silent areas

Experts still recommended caution.

“It is important to move beyond hotpots – we know surveillance is functioning there, that’s why a lot of cases,” said Giridhar R Babu. “We need to be hugely suspicious of silent areas.”

Otherwise, he warned, once the lockdown is lifted, “it is fire everywhere, especially with the inter-state migration”.