By Preetha Nair
New Delhi, July 24, 2020: The results of the Seroprevalence study in the national capital indicate that India will achieve herd immunity soon, says leading epidemiologist Jayaprakash Muliyil, chairman of the Scientific Advisory Committee of the National Institute of Epidemiology.
Seroprevalence is the number of persons in a population who test positive for a specific disease based on serology (blood serum) specimens; often presented as a percent of the total specimens tested or as a proportion per 100,000 persons tested. As positively identifying the occurrence of disease is usually based upon the presence of antibodies for that disease (especially with viral infections such as Herpes Simplex, HIV, and SARS-CoV-2), this number is not significant if the specificity of the antibody is low.
In an interview with Outlook’s Preetha Nair, Muliyil, who also served as the principal of Christian Medical College, Vellore, talks about how the Coronavirus situation in the country can be tackled without locking down the cities.
Jayaprakash Muliyil: What do you make of the Sero survey results which say that 1 out of every 5 persons in the national capital is exposed to Coronavirus and has developed antibodies?
Outlook: It is a big number. It can be interpreted as a large number of the population having already been infected. The virus is all over the place. Lakhs of people in Delhi have been infected and they all survived. You have to remember that we were expecting that once we reach the herd immunity level, which is close to 50 -60 per cent, the whole thing will settle down. If some old containment areas in Delhi are getting quiet and are not reporting any more cases, we can say that they are getting into the herd level of immunity.
One-fourth of Delhi developed immunity without a vaccine. Is that a good sign?
The result is pretty encouraging. This is herd immunity. A vaccine is supposed to do this. Unfortunately, we don’t have one. It would have been tragic if there were only deaths and no immunity. This result means we are not completely lost. The news of the vaccine from Oxford is also good. Once we reach herd immunity, we can unlock gradually. The reason is that lockdown doesn’t prevent transmission, it only causes inconveniences and affects the industries. Despite all the containment efforts, people got a high level of immunity. That means the virus is happily moving around.
Does it mean that India is moving towards herd immunity?
I think so — faster than we all thought. In a few weeks, we will hopefully find cases dwindling everywhere, at least in Delhi. Even in Mumbai, cases are coming down in most of the containment areas. It means that we are fast approaching herd immunity.
The study was carried out in 11 districts between June 27 and July 10. Do you think the number could be more than projected in the survey?
The figures are not current ones as it refers to the infection that occurred two weeks ago. The last date of the survey was July 10. That refers to an infection caused towards the end of June. After that, so many people must have been infected. So it’s old news anyway. Antibody normally develops two weeks after the infection. The numbers must be higher now. The numbers we are saying here are underestimated.
If an individual has developed antibodies against the virus, does that mean he/she is protected from Coronavirus?
In my opinion, the person is protected for a long time, maybe even for lifetime. It’s not the first virus to come into the world. We, doctors, learn about hundreds of viruses. All of them produce immunity, which is mostly a long-lasting one. I agree that there are some exceptions. This virus, we thought, is going to be an exception. Now we know that it is also behaving like any other virus. If a person gets re-infected with coronavirus, his/her body will make sure that he/she doesn’t die of this disease.
Do these Sero survey results mean a good news for people of Delhi?
Good news is that we started with zero immunity and now at least in Delhi, 23.5 percent are immune. Once we reach 50 percent, the disease will stop showing its epidemic character and it will become a sporadic disease. Then doctors can look after patients without any anxiety and there won’t be any need for quarantine. I would say that all the quarantine business and isolation is not necessary. You only have to worry about people who fall sick. So many lakhs were infected by the virus and recovered. What is the point in hunting the virus?
At least in Delhi, they should just concentrate on Covid tests and treating fever and cough. The focus should be on preventing deaths rather than counting the virus.
Is there a reason to worry as 77 percent of the population is still vulnerable. Should there be more containment measures?
That is the Indian mentality. I don’t agree with this view. It will only increase the suffering of human beings. This epidemic is going to end on its own when we reach herd immunity. We are unable to stop it. We can only slow it down or prolong the whole thing. Most people don’t die when they contract the infection. The disease is not that dangerous. Lockdown doesn’t help. If there are enough beds available in Delhi, the government should gradually open up. Otherwise it will only increase the sufferings of the people.
In Delhi, cases seem to be on a decline.
It happens in herd immunity. In Maharashtra also, the same phenomenon is happening. High containment areas like Dharavi are reporting less cases now. In Chennai too, the number of cases are coming down. Kerala was hoping to eliminate the virus. Unfortunately, it didn’t happen for obvious reasons. The cases surged after the return of lakhs of people from abroad and other states.
Source:outlookindia.com