Third sero survey: Faridabad to be tested again due to 14% inconclusive results

A day after the results of the third statewide serological survey revealed that 14% of the samples collected from Faridabad were found to be inconclusive, the state health department on Tuesday announced that resampling would take place on October 25 and 26 in Faridabad district

A day after the results of the third statewide serological survey revealed that 14% of the samples collected from Faridabad were found to be inconclusive, the state health department on Tuesday announced that resampling would take place on October 25 and 26 in Faridabad district.

Officials said that preparation for the sero survey will be completed by October 22 by the district health department after which fieldwork for collecting samples will start. The testing of samples will be done between October 27 and 29. (Parveen Kumar/HT Photo)

Rajeev Arora, the additional chief secretary for health, Haryana, said, “As 14% of the samples collected from Faridabad yielded inconclusive results, the survey will be carried out again in Faridabad district. Sampling for the survey will be done on October 25-26 and results will be declared by November 1.”

Officials said that preparation for the survey will be completed by October 22 by the district health department after which fieldwork for collecting samples will start. The testing of samples will be done between October 27 and 29.

In the third serological survey, the Faridabad district reported the lowest seropositivity at 64.2%. In urban areas of the district, the seropositivity was found to be 64.1% while in rural areas, it was 64.2%. In the Faridabad district, 1,320 samples were collected for the survey conducted in September this year.

Dr Vinay Gupta, the chief medical officer of Faridabad district, said, “In the CLIA test (the type of serological test done by the health department this time) conducted for the sero survey, if results are above 0.3, then it is considered positive but if the result is below 0.2, then it is negative. In the samples collected from our district, results of 14% samples were between 0.2-0.3, which is why the survey will be conducted again.”

Gupta said that the survey is being conducted again as the current seropositivity of 64.2% is based only on results 86% of the samples. “As results for 14% of the population were inconclusive, we cannot say for sure that the current seroprevalence is correct. It can be possible that whole of the 14% of the population have antibodies developed or partially. As it is a big number of the sample size, the survey has to be conducted again,” he said.

A serological survey finds the level of antibodies that may have been developed either after an infection or being vaccinated. The results will help the department plan strategies and assess their preparedness for the third wave of Covid-19. In the third sero survey, children were included for the first time to assess the level of immunity in this vulnerable and unexposed cohort.