NCDC Report on Sero Survey: 23% of people living in Delhi have COVID-19 antibody
The National Centre for Disease Control (NCDC), Government of India, has officially published the results of the sero-surveillance conducted in India. From June 27 to July 10, random blood samples of more than 20,000 people living in Delhi were taken to test for the antibodies to the COVID-19 virus.
The results show a ray of hope as around 23% people who were a part of the survey have had contracted the virus in some form, but have become immune to it for a period of few months. Out of 19.8 million people living in Delhi, 4.5 million people have been infected. Out of these infected individuals, only 0.123 million people are the confirmed COVID-19 cases, as per the official data. Out of these 0.123 million people, around 3,700 people have died. Thus, the Infection Fatality Rate (IFR) is 0.9 per 1000 people. As per this data, the fatality rate in India is much less than the rest of the countries such as the US, Germany, etc. but is more than the tropical countries such as Thailand.
On Saturday, the Delhi Government began sero-survey in Delhi to determine the spread of the deadly virus. Chief Minister Arwind Kejriwal stated that his government is deploying a five-point action plan to fight against the deadly virus-- Testing and isolation, providing oximeters and oxygen concentrators, plasma therapy, screening, and survey.
In this, the blood samples were collected from random people to study the scale of undetected infections with the help of rapid testing. Around 20,000 were tested till July 10 to determine the presence of IgG antibody.
As per the National Centre for Disease Control (NCDC), the results of this survey will be used to monitor the trend of the infection in the community, will reveal the extent of COVID-19 spread in Delhi and such tests will be conducted periodically.
Auxiliary nurse midwives (ANMs) and lab technician teams (posted at mohalla clinics and government dispensaries) visited door to door to collect blood samples in 11 districts of the Capital.
On its first day, 30 teams were created to carry out the door to door survey in the Central district of Delhi. On Monday, sero-survey began in New Delhi district and collected 169 samples only, based on the population. The Northwest district collected the highest number of samples in Delhi due to its population.
The survey was jointly carried out by NCDC and the Delhi Government. NCDC functions under the Central Government. Under the collaborative survey, at least 30% of the samples from each ward were from the age group-- 1 to 18 years. The study was voluntarily and was carried out on those who are living in the city for at least six months.
The teams carried questionnaire having questions related to the health, travel and contact history, consent forms, kits for collecting blood, PPE and bags to dispose of the biomedical waste after each survey.
Earlier, ICMR announced the result of its pilot sero-surveillance which was carried out on 26,000 people pan India. The survey revealed that the urban areas have about 1.09% higher infection rate than that of rural areas. The study concluded that 0.7% of the population have been infected in the past.
Also, the Indian Council of Medical Research, ICMR has issued an advisory to all the states of India to conduct serosurvey to monitor the Coronavirus pandemic. The advisory further states that these tests can be carried out on frontline workers, medical professionals, vendors, police personnel, the staff of restaurants and grocery shops, etc. In addition to these, individuals residing in the containment zones and patients with chronic illness tuberculosis, HIV, etc. will also be covered.
The survey will also be conducted on asymptomatic individuals and the previously infected COVID-19 hit patients that have now recovered. The survey will be conducted with the help of the ELISA test kit.
What is sero-surveillance?
In serosurvey or sero-surveillance, testing of blood serum of a group of individuals is conducted to detect the presence of antibodies against the infection, in this case, SARS-CoV-2. This is done to identify the individuals who were previously been infected with the virus and have now recovered.
Who will conduct the sero-surveillance?
The sero-surveillance will be conducted by the Indian Council of Medical Research (ICMR) and the National Centre for Disease Control (NCDC) in collaboration with the state health departments and recognized bodies.
Why sero-surveillance is preferred?
The Ministry of Health and Family Welfare, GOI, has so far stated that there's no evidence of community transmission of the deadly coronavirus in India. The Ministry has stated that in some clusters large outbreaks have occurred in India but the cases have not exponentially risen as in the case of community transmission.
Thus, this serosurvey is conducted so that the government agencies could track COVID-19 trends and it will also help in keeping a check on the community transmission of the virus.
How the sero-surveillance will be conducted?
The serosurvey will consist of 10 health organizations from each district, out of which 6 organizations will be public and 4 organizations will be private. The serosurvey will have two groups-- low-risk population and high-risk population.
The low-risk population group will consist of outpatient attendees, pregnant women, etc. while the high-risk population group will include healthcare workers and other frontline workers.
A total of 50 samples per week and 200 samples per month will be collected from the low-risk population group while 100 samples per week and 400 samples per month will be collected from the high-risk population group. The combination of RT-PCR and ELISA test kits will be used in the serosurvey for the detection.
The top 10 cities of India (who have registered the highest number of COVID-19 cases) will be covered in this survey to monitor and track the community transmission in the country. Apart from this, the serosurvey will also be conducted in 60 Indian districts of 21 States and UTs. This survey will be classified into four stages-- zero, low, medium and high.
The initial rounds of the survey will help in determining the prevalence of the COVID-19 infection while the other rounds will help in monitoring the trends of the virus in the community. The findings of the survey will also help the government in taking further decisions related to the lockdown.
Pilot Sero Survey by ICMR
In May 2020, ICMR (Indian Council of Medical Research) carried out sero-surveillance across 83 districts in 21 states in India and the blood samples of 26,400 individuals were collected.
A major difference between the serosurvey carried out by ICMR and NCDC and Delhi Government is that ICMR's survey collected 26,400 randomly while NCDC and Delhi Government will collect 20,000 blood samples in which 30% would be of minors.