A study by Indian Council of Medical Research (ICMR) indicates patients with severe acute respiratory illness (SARI), who contracted the coronavirus infection, did not have any travel or contact history. ICMR, an important body in the country's fight against the deadly coronavirus infection, concluded 39.2 per cent of COVID-19 cases did not report any history of contact with a known case or international travel.
The ICMR conducted surveillance among SARI patients, as it can help identify the spread and extent of transmission of coronavirus. SARI surveillance was initiated in the early phase of the COVID-19 outbreak in India. The study was also to check the possibility of community transmission of the viral infection.
The study involved examining SARI patients admitted at 41 sentinel sites from February 15 onwards were tested for COVID-19 by real-time reverse transcription-polymerase chain reaction. Most patients in India have acquired the viral infection from their travels to foreign countries having reported positive coronavirus cases, or establishing contact with somebody who has traveled to these countries. The stage of community transmission is arrived when it is not possible to trace the origin of the viral infection and there is an exponential rise in the number of positive cases.
The median age of COVID-19 positive SARI patients was 54 year (interquartile range: 44-63), and 85 (83.3 per cent) were males; 83 (81.4 per cent) of the affected patients were more than 40 years of age. Positivity was higher in males (2.3 per cent) and in 50-70 years of age group (4.4 per cent), said the study.
"COVID-19 positivity among SARI patients increased from 0 per cent before March 14, to 2.6 per cent by April 2. In 15 states, more than one 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 case or international travel, and such cases were reported from 36 Indian districts in 15 states. These districts need to be prioritized to target COVID-19 containment activities", said the study.
Maharashtra reported the highest 21 SARI patients who tested positive for COVID-19. Delhi had 14 cases followed by Gujarat with 13 cases. ICMR has said the data involved in the study is not representative of the entire district or state.
In the study, a total of 5,911 SARI patients were tested for COVID-19. Of these, 104 (1.8 per cent) were tested positive. Among the 965 SARI patient samples that were tested retrospectively between February 15-29 and March 19, two (0.2 per cent) were positive for COVID-19. When the COVID testing strategy was expanded to include all SARI patients, a total of 4946 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.
According to the study, in the 12th week, 2 out of 106 SARI patients were found positive for COVID-19. The steep rise came in the 13th week, where the number of positive cases jumped to 48 out of 2877 SARI patients. Between March 29 and April 2, 54 tested positive out of 2,069 SARI patients.
"Of the 102 COVID-19 positive SARI patients, 40 (39.2 per cent) did not report any history of contact or international travel, two (2.0 per cent) reported contact with a confirmed case and one (1.0 per cent) reported recent history of international travel. Data on exposure history were not available for 59 (57.8 per cent) cases", said the study.
The study concluded that COVID-19 containment activities need to be targeted in districts reporting COVID-19 cases among SARI patients." Intensifying sentinel surveillance for COVID-19 among SARI patients may be an efficient tool to effectively use resources towards containment and mitigation efforts, said the study.