16.5% of 800 respondents have antibodies, shows sero survey

At least 16.5% of the district population surveyed for a serological study last month has developed antibodies to fight the SARS-CoV-2 virus that causes the coronavirus

At least 16.5% of the district population surveyed for a serological study last month has developed antibodies to fight the SARS-CoV-2 virus that causes the coronavirus disease (Covid-19), as per the results announced on Monday.

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This was the second round of serological survey in the state, conducted on October 19 and 20 among 800 people in the district. In the first round held in August, the district had a seropositivity rate of 10.8% among 1,049 people. Although the sample size has decreased in the second round, seropositivity rate has increased.

The survey found the overall prevalence of the virus to have increased, with about 90% of the respondents in Gurugram claiming not to have any history of Covid-19 symptoms.

The overall seropositivity of the state has also increased by over six percentage points, compared to the first survey. This time around, at least 14.8% population in the state has developed antibodies against the virus without showing any symptom, which is higher than the 8.1% recorded in August.

Haryana health minister Anil Vij said, “The sero prevalence of Haryana is found quite less than the other sero surveys conducted in various states. The health department has been on its toes for the last seven to eight months and has done commendable work in controlling the spread of Covid-19 as shown by the two rounds of sero survey conducted in the state of Haryana.”

Similar surveys in Delhi showed that the prevalence of antibodies increased from 22.8% in July to 29% in August. Likewise, in Ahmedabad, it increased from 17.68% in June to 23.24% in August.

In Haryana, across the 22 districts, 16,512 samples were collected (720-800 samples in different districts), out of which 35 were rejected. As per the data, 2,432 of 16,477 samples were positive, 23 had inclusive results, while the remaining were negative. The data of the survey was collected using a digital tool — COVID19 Sero Survey Mobile Application — developed by the Haryana IT department.

Dr Usha Gupta, director, Integrated Disease Surveillance Programme (IDSP), said, “A stratified multistage random sampling technique was used. Twelve rural and four urban clusters were randomly selected for taking samples in each district. Blood samples were collected from selected individuals after taking written consent and their sera were tested for IgG antibodies using ELISA test kit approved by the Indian Council of Medical Research.”

Gupta, said, “The SARS-CoV-2 seropositivity observed in urban area is 19.8% and in rural area is 11.4%, which were 9.6% and 6.9% in the first round. Rural areas of Faridabad and Jind were found to have highest positivity rate of 25.5%, while urban areas of Faridabad, Yamunanagar and Panipat had the highest seropositivity rates of 40.2%, 37.1% and 36.3%, respectively.”

The survey covered population from different age groups, with the majority in the 28-47 age group. Nearly 91% of the sample size had no co-morbidity issues. Those with co-morbidity were patients of diabetes and hypertension.

In Gurugram, a total of 800 were tested for IgG antibodies, which are developed in the body a week after the infection. Since a high proportion of asymptomatic or Covid-19 patients with mild symptoms are missed from the data of laboratory-confirmed cases, the serological survey covers this section to study the prevalence of the virus.

The findings show that at least 131 (16.5%) of the 800 had antibodies, while 81% of the samples tested negative for the antibodies. The remaining 2.6% showed inclusive test results. Nearly 632 people who gave their blood samples for the survey never got tested for Covid-19 before, while 146 had tested negative for the virus.

High prevalence in urban areas

Since the sample size of the survey covers nearly 60% of rural and 40% urban population, Rajeev Arora, additional chief secretary, health department said, “It has been observed that the risk of transmission is higher in urban areas as compared to rural areas. This only means that a larger portion of the population must continue following Covid appropriate behaviour.”

He said, “A sero survey is about testing a group of individuals for the presence of antibodies as it helps in understanding the number of people affected by the disease. The study helped us to determine the burden of COVID-19 at the community level in the state and monitor the trends of transmission of SARS-CoV-2 infection.”

Dr SB Kamboj, director general of health services, said, “Although 14.8% population of Haryana has developed antibodies, a significant proportion of the population is still vulnerable. Therefore, the containment measures need to be continued with the same rigor. Further, other non-pharmacological interventions, such as physical distancing, use of face mask, hand hygiene, cough etiquette and avoidance of crowded places, must be followed strictly and must not be overlooked.”