Nearly 40 per cent of patients with pneumonia-like illnesses, who had tested positive for Covid-19 under community surveillance from samples picked up from hospitals by the Indian Council of Medical Research (ICMR), did not report any history of international travel or contact with a known case, reveals the latest study released by the national research body.

The research paper, published as India enters the third week of a 21-day lockdown, reveals that ICMR had recorded two Covid-19 positive patients among 956 with severe acute respiratory illness (SARI), with stored samples tested retrospectively between February 15 to 29, and March 19.

While 104 of 5,911 SARI patients tested positive for Covid-19 in 52 districts across 20 States and Union Territories, ICMR has published definitive data on 102 of them.

Of these, 40 (39.2 per cent) did not report any history of contact or international travel, two patients reported contact with a confirmed case and one patient reported recent history of international travel. Data on exposure history were not available for 59 (57.8 per cent) cases, the study further says.

China reported cases in December 2019 and WHO declared it a public health emergency of international concern on January 30, the same day India reported the first lab-confirmed case of Covid-19, from Kerala.

Sample studies

On February 15, ICMR labs started picking up throat and nasal swab samples of SARI patients for the virus at 41 sites — as the symptoms of Covid-19 mimic flu-like illnesses, including dry cough, breathlessness, fever and pneumonia — to check if the disease had entered the community spread phase.

Till March 18, ICMR had maintained that the 820 samples that it had picked up in two batches were all negative for the virus. From March 19 onwards, it stopped sharing data in the public domain and, on March 20, it re-hauled the testing strategy to include all SARI patients under Covid-19 surveillance, after the initial two positive cases were noticed in these stored samples of SARI patients hospitalised since February 15.

“When the Covid testing strategy was expanded to include all SARI patients, a total of 4,946 samples yielded 102 (2.1 per cent) cases. The positivity increased from zero during the initial weeks to 2.6 per cent in the 14th week,” the ICMR study said.

Pandemic hotspots

Maharashtra reported the maximum number of cases, spread over eight districts, with 21 positives (3.8 per cent) of 553 SARI patients, followed by Delhi with 14 positives (5.1 per cent) of 277 cases in five districts and Gujarat with 13 positive cases in 792 patients in four districts. The majority of the SARI cases surveyed were in Gujarat (792), Tamil Nadu (577), Maharashtra (553) and Kerala (502).

ICMR stated that 36 districts from where Covid-19 patients were being picked up need to be prioritised to target Covid-19 containment activities. “In 15 States, more than 1 per cent of SARI patients were Covid-19 positive. About a third of Covid-19-positive SARI cases did not have any history of contact with laboratory-confirmed cases or international travel, and such cases were reported from 36 Indian districts,” it added.

The study also noted that Covid-19 positive cases were higher amongst males and patients over 40 years. Eighty-five of the 104 positive patients, or 83.3 per cent, were males. Of them, 83 patients, or 81.4 per cent, were over 40 years of age.

Age-wise break-up

In the age group of 50-59 years, up to 31 from the 637 samples taken (4.9 per cent) tested positive. This was followed by 26 (3.9 per cent) of 672 patients in the age group of 60-69 years. In the age group of 40-49 years, 16 of 634 patients (2.5 per cent) tested positive. In the age group of 70 and above, 10 of 592 patients were positive, or 1.68 per cent. Two (0.5 per cent) of 368 children aged 0-9 years and 17 (0.7 per cent) of 2,390 patients from 20 to 39 years also tested positive.

ICMR has recommended that surveillance among SARI patients be intensified for better containment of the pandemic.

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