Seroprevalence of SARS-CoV-2 infection in Srinagar

Srinagar: Government Medical College (GMC) Srinagar conducted studies to estimate the seroprevalence of IgG antibodies against SARS-CoV-2 among health care workers and the general population of District Srinagar from 15 June to 15 July 2020.

In a statement issued to Kashmir Indepth News Service (KINS) reads, The study was conducted by the Department of Community Medicine in collaboration with the Department of Biochemistry, GMC Srinagar.

Prior to the study, survey teams were trained for administration of questionnaire and  collection and transport of blood samples. Healthcare workers from all eight associated hospitals of GMC Srinagar, Government Dental College Srinagar, District Hospital Srinagar, and nine other Sub-District Hospitals/Primary Health Centers across District Srinagar were invited to participate, said Dr. S. Muhammad Salim Khan, HOD Community Medicine and Principal Investigator of the studies.

‘A total of 2914 blood samples of health care providers were analyzed for the presence of IgG antibodies against SARS-CoV-2 using Chemiluminescent Microparticle Immunoassay (CMIA) by Abbott Laboratories. The test has a high sensitivity and specificity for identification of IgG antibodies against SARS-CoV-2. The test provides information about past infection due to SARS-CoV-2’, said Dr. Sabiya Majid, HOD Biochemistry and Co-Principal Investigator.

‘Seventy-two HCWs were positive for IgG against SARS-CoV-2 giving a prevalence of 2.5%. Out of the 72 HCWs, 50 were male and 22 were female. Among HCWs who participated in the study, the prevalence was 2.7% among male HCWs and 2.1% among female HCWs. Of the IgG positive HCWs, 12 were above 60 years of age. The IgG positives included 27 doctors, 9 nurses, 10 technicians, 2 ambulance drivers, and 8 hospital security staff among others. 339 HCWs reported to have at least one contact with a known SARS-CoV-2 (COVID-19) positive case’, said Dr. Inaam ul Haq, assistant professor Community Medicine and co-principal investigator.

To estimate the prevalence of IgG antibodies against SARS-CoV-2 in the general population, a total of 2923 blood samples were collected and transported to the laboratory for testing, under standard precautions. The samples were collected from people, >18 years of age, visiting 20 selected hospitals across District Srinagar plus three other sites in the District. The study participants were informed about the purpose of the study and a written consent was taken from all the study participants. The study revealed that 3.8% (111 persons) of the population had presence of IgG antibodies against SARS-CoV-2, said Dr. Mariya Amin Qurieshi, assistant professor Community Medicine and co principal investigator of the study.

If we apply this estimate to the current adult population of District Srinagar, which is approximately just over 10 lakh, then the number of IgG positives in the District at the time of the survey was expected to be 38000. Of the 111 IgG positives, 63 were males and 48 were females. The prevalence of IgG positives was 4.3% among males and 3.3% among females. 115 persons reported to have Influenza-like symptoms in the 4 weeks prior to the survey and out of them 12.2% showed presence of IgG antibodies, said Dr. Salim Khan.

IgG antibodies against SARS-CoV-2 usually develop two weeks after the infection. Thus, the presence of IgG antibodies is indicative of past SARS-CoV-2 infection. A recently infected person will not show presence of IgG antibodies. IgG against SARS-CoV-2 should be perceived as diagnostic of recent infection of COVID-19. A person with IgG antibodies against SARS-CoV-2 is usually not infective to others. For diagnosis of current infection and possible potential of infecting other persons, RT-PCR is the diagnostic modality of choice. Recently Rapid Antigen Tests have also been used for diagnosis of current infection.

The results of this seroprevalence study show that, on an average, 3.8% people in District Srinagar have been infected with SARS-CoV-2. Given the current scenario of positive cases emerging from the District, it is expected that the seroprevalence may further increase in the near future as more and more individuals become infected and develop antibodies against the virus, said Dr. Samia Rashid, Principal GMC Srinagar who mentored the studies.

The study on health care providers is the first of its kind in the country and only few states/ UT have conducted community based study. The study had Institutional funding and also supported by District Disaster Management Authority (DDMA), Srinagar while Directorate of Health Services Kashmir including CMO Srinagar and BMO & ZMOs of Srinagar and medical Superintendents of Associated hospitals and doctors & interns of Community Medicine provided full support to the studies.

Both the studies were provided ethical clearance by Institutional ethical committee of Government Medical College Srinagar.(KINS)