Health officials in the district have undertaken the third round of serological surveillance to determine the development of antibodies against COVID-19 among the people. The exercise, undertaken across the State, would help in indicating herd immunity, officials said.
Herd immunity is a form of protection from an infection that can occur when over half of a population is immune to it, either through vaccination or from getting infected, M. Yazhini, City Health Officer told The Hindu .
The Directorate of Public Health would study the incidence of infection, identify hotspots and inform local health officials, who would take blood samples to test for antibodies for COVID-19. In Tiruchi city, eight such locations have been identified.
“We took 30 samples from each location. So, 30 samples of 30 different individuals in 30 adjacent houses,” Dr. Yazhini said.
Residents who were unwilling to take part or unavailable were skipped. The localities identified were different from those surveyed in the previous two rounds. The samples are sent to a laboratory of the DPH to test for antibodies. “Our nearest lab is in Manapparai, and samples from over six districts have been submitted there for processing,” she said.
In the first serosurvey, they found 30% of the population with antibodies, while in the second, which was between the first and the second, it was around 27%. “This time around, we are expecting at least 40%,” she said.
The vaccination drive, which has picked up pace in the district, would contribute to the population with antibodies. “We can soon reach over 50% and achieve herd immunity, protecting us from future waves of COVID-19,” she added.
A similar exercise is also being undertaken in rural parts of the district, where 27 hotspots have been identified. Once all the samples are submitted, results of the serosurvey could be expected within 10 days.
