Although the people are still scared about it, the panic of COVID-19 has now lessened in the public. Since the world started to unlock gradually, people started venturing out and the cases started rising. However, the recovery rate in India currently ranges from 76-77% approximately, possibly due to aggressive testing and timely treatment provided by the health infrastructure of our country. Apart from the commendable job seen in the health sector, people seem to have developed ‘Herd Immunity’.
Herd Immunity
In recent times, there has been a lot of news and discussions about herd immunity in our country. But what exactly is it? The Centers for Disease Control and Prevention (CDC) states, “A situation in which a sufficient proportion of a population is immune to an infectious disease (through vaccination and/or prior illness) to make its spread from person to person unlikely. Even individuals not vaccinated (such as new-borns and those with chronic illnesses) are offered some protection because the disease has little opportunity to spread within the community.” It is also called Community Immunity.
The vaccine is yet to arrive in the market, so how do we know if people in India have developed herd immunity against the novel coronavirus or not? The answer to this is Serological Survey. But now again, what is this new term?
Serological Survey
Antibodies are the proteins that are developed to prevent external organisms from entering our body. Serological surveys or Sero-Surveys are carried out in a country to test if people have developed antibodies against a particular disease or not. In the current scenario, that disease is COVID-19. The World Health Organization (WHO) explains “Antibodies to COVID-19 are produced over days to weeks after infection with the virus. The presence of antibodies indicates that a person was infected with the COVID-19 virus, irrespective of whether the individual had severe or mild disease, or even asymptomatic infection.”
This survey is not a test to check if the person is suffering from COVID-19 or not. It is a simple blood test, to understand the immune response to the virus. Also, this test is not conducted on all the citizens of the country, a sample or a group of people are selected and the tests are carried out.
In its press release on 12th May 2020, the Indian Council of Medical Research (ICMR), New Delhi stated, “India is conducting a community based sero-survey to estimate the prevalence of SARS-CoV-2 infection in Indian population. This household level cross-sectional survey will cover 24,000 adults distributed equally across four strata of districts categorized on the basis of reported cases of COVID-19.” The survey is underway, being conducted in certain states across India.
In another press release by the ICMR, it mentions the Possible groups/ community/ population based on specific requirement for sero-survey by using IgG Elisa test, which include:
- Immuno-compromised patients
- Individuals in containment zones
- Health Care Workers
- Security personnel
- Police and paramilitary personnel civil defense & volunteers
- Press corps
- Rural, tribal population (after reverse migration)
- Industrial workers or labour force
- Farmers, vendors visiting large markets
- Staff in municipal bodies
- Drivers
- Banks, post, couriers, telecom offices
- Shops
- Air travel related staff
- International operations
- Congregate settings
- Prisons
How is it done?
- 5ml of blood samples are collected from the selected sample.
- Blood and plasma are separated. The liquid part of the blood known as ‘serum’ is examined, to understand the immune response to the virus.
- The collected blood samples are tested for IgG (Immunoglobulin G).
- If a person has tested positive for IgG, it means that he/she has been infected with the novel coronavirus in the past.
- The tests are conducted on a community level and can be used on asymptomatic people or those who have been tested positive for COVID-19.
Therefore, once the tests are conducted, its results will show if people have developed any antibodies to fight COVID-19, if they were ever infected with the virus and if not, what were those factors which prevented them from remaining unaffected by the virus. According to these results, the decisions regarding the treatment, vaccinations or public restrictions, etc. will be taken by the medical and government authorities.
However, it is to be noted that the virus is still there out there and people need to stay home and not venture out. All the preventive measures are to be followed strictly until it is completely over, because your safety is in your hands!
