This blog describes How the Mumbai Sero Survey was Conducted amongst Slums & Non-Slums in a densely populated city like Mumbai. Furthermore, this will help to understand our immunity level against COVID-19.
Mumbai Sero Survey Importance
A seroprevalence study analyzes the impact of a disease, its mortality, and herd immunity based on gender differences. A serology test does this. The diagnostic test identifies how a type of person produces antibodies and antigens against an illness like coronavirus disease. Therefore, this shows how immune their system is against the virus.
While antibody test for COVID-19 depicts the number of people exposed to coronavirus earlier but asymptomatic to the disease, antigen test for COVID-19 indicates how many of them are currently active cases. Learning about both these numbers considering asymptomatic & symptomatic counts helps researchers derive the criticality of the virus in a type of individual. Thus, helping them understand a person’s immunity against the virus. These results become extremely important for health experts. Hence, the government learns, understands and tackles the situation for the given population.
In July, BMC officials initiated survey in 3 wards of Mumbai: Matunga (FN ward), Chembur (MW ward), Dahisar (RN ward). Screened over 8,000 residents of Central Mumbai, targeting slum (high density of population) & non-slum (low density of population) both. This was the largest survey study for Dharavi residents, conducted by BMC, TIFR & NITI Aayog. CrelioHealth & Thyrocare contributed as the operational partner in the sero survey to digitize the entire screening workflow for the survey.
Different parts of India like Bengaluru, Delhi, etc. are conducting it as a necessary step to screen SARS-CoV-2. This shows the rate of spread and the likelihood to contain the virus within the population.
Know more about this Sero-prevalence Study
For 18 consecutive days, over 40+ phlebotomists accompanied by BMC officials went door to door to collect samples and capture household survey details, on the mobile app (powered by CrelioHealth). The technology enabled phlebotomists to digitally capture household details and take samples on pre-barcoded tubes by Thyrocare; scaling the rate of the entire operation. Batches of samples for high population density areas, i.e. slums & low population density areas (i.e. non-slums) separated to specifically study herd immunity in each of them.
Kasturba (Nair) Hospital, Mumbai tested the Collected samples for COVID-19 antibodies. The center utilized CrelioHealth Lab Automation Software Interfaces to process samples every day. Moreover, the automated testing facility enabled error-free testing of more than 500 samples daily. Reports printed soon after testing and were circulated to slums & digital reports were emailed to non-slums participants.
Utilizing digitization right from capturing sero survey questionnaires to sample collection with barcodes. Automated testing to report delivery; highly maintained the quality and accuracy of the information throughout the process. Despite the geographical distance between each center and lockdown limitations, the dedicated contributors & latest tech support enabled faster testing with error-free reports at scale.
Results & Impact
The finding derived the rate at which COVID-19 is spreading amongst the population of Mumbai, India.
- Out of 6936 people tested – 61% were from slums & 39% were from the non-slum/residential areas
- Exposed 57% of the slum population & 16% of the residential population (non-slum) developed antibodies against COVID-19 disease.
- Women generate a higher amount of antibodies as compared to men in both slum & non-slum areas.
- Among people in slums, 59.3% of women tested, and 53.2% of the men tested had antibodies against SARS nCOV.
- In non-slum areas, 16.8% of women tested and 14.9% of men tested had developed antibodies.
- *Infection Fatality rate is 0.05 – 0.1% as compared to **Case Fatality rate which is 5-6%
*Infection Fatality rate is the ratio of No. of non-survival tested positive (COVID-19 infected) to the Total No. of Tested Positive (COVID-19 Infected)
**Case Fatality rate is the ratio of the No. of non-survival suspected to have COVID-19 to the total No. of suspected COVID-19 case
Further, the next course of the sero survey is to begin in the 2nd week of August. Also, this targets the same wards to study if any change persists in the antibody development after 3 weeks of round 1.
Thus, based on this study, researchers will utilize the data. The government will plan the next course of action to manage the pandemic while continuing to revive the country.