A Serosurvey by Karnataka has revealed that around 16 per cent of the people in the state have developed antibodies against COVID-19 virus.
Health and Medical Education Minister Dr K Sudhakar speaking to media in Bengaluru on Wednesday said the survey to estimate the prevalence of COVID-19 in Karnataka was done from September 3-16, 2020.
This included the proportion of people who had COVID-19 infection recently and those currently having active SARS-CoV-2 infection. The sampled population surveyed were all adults aged 18 years and above. All 30 districts of the state, including eight zones of BBMP, were included in the survey. The survey was conducted in hospitals and selected population settings.
Three groups of the population which were covered include -- (i) low-risk group, i.e., pregnant women attending the antenatal clinic, persons attending the outpatient department in the hospitals/attendees of children or patients; (ii) moderate-risk group, i.e., persons moving in the community like bus conductors, vendors at the vegetable markets, health care workers, individuals in containment zones and congregate settings such as markets, malls, retail stores, bus stops, railway stations, pourakarmikas / waste collectors; and (iii) high-risk group .i.e. elderly and persons with comorbid conditions.
The study used Rapid Antigen Test (RAT) and RT-PCR for the diagnosis of acute infection. At the same time, serum testing for IgG antibodies was conducted to know the protection offered by the immune response. The standard ICMR protocols were used, and ICMR approved laboratory network in the state was utilized, Dr Sudhakar stated.
Of the 16,585 persons surveyed covering the three risk categories, the analysis was done on results for 15,624 individuals whose RAT plus RT-PCR and COVID Kavach ELISA antibody test results were matched in the line list.
Giving a brief explanation of the survey, the Minister said that, the survey revealed that 16.4% of the people were infected in the past and found to have antibodies against COVID-19 in the surveyed population. This amount is 29.1% in Delhi, 16% in Mumbai non-slum settings, 57% in slum settings, 36.1-65.4% across five prabhags in Pune, 7.8% in Indore, 22.7% in Puducherry, and 32.3% in Chennai.
The national seroprevalence survey conducted by the Indian Council of Medical research found a seroprevalence of 0.7% in the first round (May) and 7.1% in the second round (August-September). Both rounds were conducted in 70 districts of the country. All these surveys capture only the evidence of infection in the past (IgG). The surveys done in other states were limited to capturing information only within the confined limits of the metropolitan area, the Minister said.
Compared to other studies in India, the survey undertaken in Karnataka has captured total prevalence, which includes information on both current and past infections. The participants were included from locations centred around 290 hospitals spread throughout the state of Karnataka at the district, taluk and rural areas. The survey employed all three tests: Rapid Antigen Tests, RTPCR, and antibody (IgG), the Minister informed.
*Other Points made by the Minister*
• The survey is useful in improving the quality of treatment and following the precautionary/safety measures.
• Mortality rate in the state is very low and recovery rate is about 95%.
• Government is willing to establish a rehabilitation centre for those who have recovered from COVID-19 infection.
*Highlights of the survey*
• Out of 7.07 crore estimated population in Karnataka, the study estimates that 1.93 crore (27.3%) of the people are either currently infected or already had the infection in the past, as of 16th September 2020.
• The infection fatality rate due to COVID-19 in the state of Karnataka is 0.05%.
• The districts with a high infection fatality rate suggest that clinical care needs to be improved in these places. The present IFR is likely an underestimate. The overall IFR based on the first round of sentinel serosurvey findings is 0.07%. The IFR reported across other cities are Mumbai (0.05-0.10%), Pune at 0.08%, Delhi is at 0.09, and Chennai is at 0.13%.
• In summary, the state is passing through different stages of the COVID-19 pandemic in the different districts. The surge in cases is yet to occur in the districts with the lowest estimated prevalence of COVID-19 (Dharwad, Gadag, Chikkaballapur, Bagalkot, and BBMP Mahadevapura).
• The study recommends establishing the district-level facility-based sentinel sero-surveillance to monitor the trend of infection in the long term systematically. This can inform local decision-making at the district level to mount the necessary public health response towards the COVID-19 epidemic in Karnataka state.
• Lastly, a follow-up survey is planned to measure the extent and speed of transmission and evaluate the impact of containment strategies over time in the state.