An ICMR study, released online, has both good and bad news on the spread of the corona virus in India. In either event, it underscores the need for wider testing, including of patients admitted to hospital with Severe Acute Respiratory Illness; acute Covid-19 cases show SARI-like symptoms.
The study examined samples of 5,911 SARI patients from 41 places between February 15 and April 2. Since ICMR changed its testing protocol on March 20, the 5,911 samples can be divided into 965 before March 19 and 4,946 afterwards. Of the 965, two were positive for corona, or 0.2%. Of the 4,946, 102 tested positive, or 2%. Even if the higher 2% number is taken as more representative, it suggests the corona infection is low.
The bad news is that of the 102 patients who tested corona-positive (the after-March 19 patients), 40 did not report any history of either travel overseas or contact with a person who had corona. That suggests community transmission has begun. But there is a caveat here.
The results are based on self-reporting, not rigorous collation of a matrix of contacts which are then investigated for corona.
It is, for instance, possible that Person A with corona didn’t know that Person B she met was infected. Had the mapping exercise been more thorough, it would have shown Person B was infected; this is called local transmission.
While all the SARI cases that were Covid 19-positive were from just 52 districts in the country, Gujarat, which has seen a high fatality relative to the number of cases detected, reported 13 of the cases, from just four districts; Maharashtra reported 21 cases from eight districts and West Bengal, where there have been many reports of mass flouting of social distancing measures, reported nine cases from six districts.
In either case, the study shows more testing as well as thorough mapping an investigation of contacts is required for a complete picture of the spread of the infection.
Given the fact that testing of SARI patients for Covid 19 would have likely gone up at the laboratories after the testing strategy was expanded to include them, and that the majority of the patients were hospitalised at public sector facilities in urban areas, it is likely that the study doesn’t capture the true extent of the spread in a district. However, the study’s findings should indicate the spread in certain areas, which makes identification of hotspots easier as also the determination of community infection.
The government changed the testing strategy for SARS CoV-2 on April 9, requiring all symptomatic (fever, cough, sore throat, runny nose) cases of influenza like illness (ILI) to be tested for the viral genetic material (PCR test) within seven days of the illness manifesting, and an antibody test after seven days of the illness, with a confirmatory PCR test if the antibody test is negative.
This is in addition to the all symptomatic cases who have undertaken international travel in the past 14 days, all symptomatic contacts of laboratory confirmed cases, all symptomatic healthcare workers, all hospitalised cases of Severe Acute Respiratory Ilness (SARI) and asymptomatic direct and high-risk contact of a confimed cases (to be tested between the fifth and the fourteenth day of having come in contact).