JIPMER Study: 1 in 20 districts in Puducherry showed evidence of COVID by end of July 2020
JIPMER proposes to undertake a repeat survey in the second/third week of September 2020 (time period B in Figure) to assess the extent of exposure by the last week of August 2020 (time point B1 in Figure) and further serial surveys at appropriate time points as the pandemic continues.
Puducherry: In an attempt to find the extent of the spread of novel Coronavirus infection (SARS-CoV-2) in the population of Puducherry, JIPMER conducted a community-based survey to study the presence of antibodies in the blood (serum). Experts from the Departments of Preventive and Social Medicine and Microbiology of JIPMER were involved in the selection of patients and collection of blood samples, the conduct of the tests as well as analysis of the results.
For this study, blood was collected from randomly-selected adults aged 18 years and above from 30 different clusters, with a ratio of 21 from urban and 9 from rural areas to reflect the population distribution of the Union Territory of Puducherry. The samples were collected from 11-16th of August 2020 (time period A in the figure below).
The presence of antibodies was studied using an immunoassay (Elecsys Anti-SARS-CoV-2; Roche) with a reported sensitivity of 99.5% and specificity of 99.8% at more than 14 days after exposure to the virus. Of the total of 869 adults tested, 43 had antibodies against novel Coronavirus (4.9%). The positivity rate for antibody was higher in the city (urban) population than in the rural population (5.7% in comparison to 3.1%) and among women than in men (6.3% in comparison to 3.6%).
The results of this study reflect the occurrence of exposure in people residing in Puducherry by the 24th of July, 2020 (time point A1 in Figure below). The total number of confirmed cases in the district by that date was 2271, with a cumulative incidence of 0.19% for the population of Union territory (=2271/12,00,000). Thus, the proportion of persons with the presence of antibodies in blood was nearly 26-fold (4.9/0.19) larger than that of the cases diagnosed by a Real-time PCR test as on 24th July.
JIPMER proposes to undertake a repeat survey in the second/third week of September 2020 (time period B in Figure) to assess the extent of exposure by the last week of August 2020 (time point B1 in Figure) and further serial surveys at appropriate time points as the pandemic continues.
