The three-day exercise of conducting the second round of serological survey in the district was completed on Friday with a total of 850 blood samples being collected to detect IgG antibodies developed against the SARS-CoV-2 virus among the population. The survey, which started on Wednesday, was affected by the incessant rain and waterlogging the district witnessed on that day, said officials.

Teams comprising lab technicians, medical officers and health workers collected 90 blood samples on Wednesday, followed by 500 samples on Thursday, and 260 samples on Friday. Similar exercise is being conducted across the state in the 21 other districts to trace the prevalence of the infection and identify individuals who have developed immunity against the infection. At least 21,000 people are supposed to be covered under the survey.

Rajeev Arora, additional chief secretary, health department, said, “The state will be releasing the survey results by the end of August. The results from the all the districts will be collated and analysed to understand the prevalence of infection and take measures accordingly.”

The purpose of the serological test is not to detect the virus but the presence of antibodies in the blood developed against the virus. It is body’s immune response against the coronavirus that produces these antibodies. Antibodies against the infection are not developed in the early days of infection. As such, these antibodies are not detected before seven to 14 days. It is for this reason the serological test is not used for diagnosing active infection. The test is also used to detect the antibodies level in recovered Covid-19 patients who can donate a part of their blood called convalescent plasma to critical Covid-19 patients.

The district’s chief medical officer(CMO), Dr Virender Yadav, said that the survey has been conducted following all the protocols issued by the state government. “Samples were collected from 16 clusters, including four in urban areas and 12 in rural areas. “Urban clusters include Tigra, Patel Nagar, Khandsa and Basai. The 12 clusters in rural areas were Daulatabad, Badshahpur, Pataudi, Bajghera, Palra, Sherpur, Sarai, Aklimpur, Inchhapuri, Bhudka, Bhorakalan and Rathiwas.

The district had conducted the first round of serological survey from June 24 till mid-July. At that time, 454 IgG antibody tests were carried out, out of which 56 were found to be positive and 398 negative.

The neighbouring state of Delhi on Thursday released the results of its second serological survey, which covered at least 15,000 people and showed that 29.1% of the city’s population has developed antibody against the SARS-CoV-2 virus. Findings showed that the prevalence of antibodies increased by over 6 percentage points as compared to the first survey held in June-July. At that time 22.86% people were detected with antibodies. In the first survey, 21,387 samples were collected, while 15,000 were collected in the second round.