Coronavirus: Community transmission was present by March third week, ICMR says in a study


In a paper published on April 9, ICMR says community transmission was seen by third week of March. The prevalence of coronavirus positive cases in the community may be much more than what SARI cases indicate as those who tested positive are restricted to select sentinel hospitals and the testing throws up false negatives.

Even as recently as March 29 when the Indian Council of Medical Research maintained that there was no case of community transmission of novel coronavirus (SARS-CoV-2) in India, the Health Ministry on its website had mentioned that there was “limited community transmission” and local transmission in a document on standard operating procedure for transporting a suspect/confirmed case of COVID-19. Now in a paper published on April 9 in the Indian Journal of Medical Research by a team led by Dr. Manoj Murhekar from the National Institute of Epidemiology, Chennai, ICMR confirms that community transmission was seen by third week of March.

If 1.9% (two of 106) patients admitted to hospitals for severe acute respiratory illness (SARI) tested positive for coronavirus during the period March 15-21, it increased to 2.9% (54 of 2,069 patients) during the period March 29 to April 2. If SARI patients admitted to hospitals February 15 and March 19 were randomly tested, the testing strategy was revised to include all SARI patients from March 20 onwards.

“When the COVID-19 testing strategy was expanded to include all SARI patients, a total of 4,946 samples yielded 102 (2.1%) cases. The positivity increased from zero during the initial weeks to 2.6 per cent in the 14th week [March 29-April 2],” they write.

Of the 102 SARI patients who positive for the virus, “40 (39.2%) did not report any history of contact or international travel” they write, thus clearly indicating that community transmission was prevalent. While two (2.0%) reported contact with a confirmed case and one (1.0%) reported recent history of international travel, exposure history was not available for remaining 59 (57.8%) cases.

The authors then add: “In 15 Indian States, more than 1% 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.”

A majority of the SARI patients were tested from Gujarat (792), Tamil Nadu (577), Maharashtra (553) and Kerala (502) with COVID-19. And these States reported the most coronavirus positive cases. positivity of 1.6, 0.9, 3.8 and 0.2 per cent, respectively.

The prevalence of coronavirus positive cases in the community may be much more than what SARI cases indicate. This is because the SARI patients testing positive for the virus are restricted to those seeking care in select sentinel hospitals that were predominantly in public sector in urban areas. “Hence might not be representative of the entire district, State or country. However, the trend of COVID-19 positivity among SARI patients could provide reliable information about its spread in the area,” they write. Also, since RT-PCR throws up false negative results, a certain number of infected patients could have been missed.

As on April 9, there were 5,865 cases and 169 deaths.