One in every five persons in Puducherry district was infected with COVID-19 by August-end, the results of a Jipmer sero-survey have found.
The findings of the sero-survey, launched in two rounds in August and September, showed that between July-end and August, the antibody sero-prevalence showed a 4.2-fold increase.
This is in keeping with the 4.1-fold rise in the number of confirmed cases over the same period in Puducherry (from 2987 to 12,331), Jipmer said in a press note.
The first sero-survey had indicated that one in 20 persons in the district showed evidence of COVID-19 infection.
The second round data indicates that Puducherry had a high rate of transmission in August. Also, the prevalence of serological evidence with antibodies in the population is much higher than detected by RT-PCR as found at two time points; 19.6 (4.9/0.25) and 20.1 (20.7/1.03) fold respectively on July 30 and on August 30.
“Thus, by the end of August, nearly one-fifth of population in Puducherry had been infected with the Covid-19 infection,” the Jipmer release said.
According to the press note, two community-based serological surveys were conducted at intervals of four weeks in an attempt to find information on the extent of spread and trend of infection.
Blood samples were collected from randomly selected adults from 30 clusters in a ratio of 21 urban and 9 rural areas to replicate the population distribution in Puducherry. The two surveys were conducted during August 11-16 and September 10-16.
In the first round in August, 869 adults were tested and 43 (4.9%) had antibodies against SARS CoV-2 with a higher positivity in urban areas (5.7% versus 3.1%) and among women (6.3% versus 3.6%). The first round data reflects the cumulative proportion of Puducherry population infected as on July 30.
In the second round, of the 898 adults tested, 186 (20.7%) had antibodies against the SARS CoV-2 infection. In the second round, the positivity rate was similar in urban and rural population (20.7% versus 20.8%) and among men and women (21.4% versus 20%).
The second-round data reflects the cumulative proportion of Puducherry population which had been infected with COVID-19 as on August 30. The number of cases recorded in the district population on July 30 and August 30 respectively were 2,987 and 12,331 with incidence rates (population estimate for year 2020 is 12,00,000) of 0.25% and 1.03% respectively, the press note said.
