After 10 months, Delhi reported zero COVID-related deaths on January 9th. A few days earlier, the latest and the biggest serological surgery conducted by the Delhi government had shown that about 56% of the over 28,000 people whose blood samples were collected in January developed antibodies against COVID-19.  

The sharp decline in COVID-19 cases across India, except a few states including Kerala and  Maharashtra is a clear indication that India has succeeded in controlling COVID-19 to a great extent. But are we really moving towards herd immunity, and can we afford to lower our guard?

“No, the virus is unpredictable and may stage a comeback,” says Dr Anurag Agrawal, director, Institute of Genomics and Integrative Biology. “These sero surveys only suggest that we have achieved some community-level immunity, not herd immunity. We need vaccines to help us acquire herd immunity and till then we need to take all the precautions we have been taking all this while, While findings of these sero surveys support the hypothesis that more than half the population in cities like Delhi may be currently immune, we need to understand this immunity to the disease is not permanent.” 

So far, India has handled the pandemic well, with per million deaths in India lower than those in developed countries. Currently, Kerala, Maharashtra, Tamil Nadu, Karnataka, and Chhattisgarh account for almost 80 percent of the total cases across the country while developed countries like France, Italy, UK, are still struggling to control the second or the third wave of infection.  

Though experts do not have a definitive answer to why cases in India have declined sharply, some believe that parts of the country may have achieved herd immunity as a result of large asymptomatic infections that went unreported.

Sero surveys

In mid last year, Council of Scientific and Industrial Research (CSIR) conducted a sero survey at its 37 laboratories and centres across the country, and participants included the organization’s  staff and their families, students, security guards, sanitation workers, and housekeeping staff. The findings suggested that the total number of cases in India were probably in the range of 100 million, about 30 times that of reported cases. The survey also found that over 50% of people who had antibodies did not develop any symptoms. 

Read more: All that we know about the COVID shots from the health ministry

Doctors say multiple factors could explain this. “One could indeed be our genetic-make up,” says Dr Randeep Guleria, director All India Institute of Medical Sciences (AIIMS). “Second could be the fact that we are a younger population in terms of average age, which is much less than the average age in America. We know that COVID-19 claims more lives in elderly population. Also, in-vitro studies have shown that the BCG vaccine, which most of us get in childhood, stimulates our immune system in a way that we also develop protection against some other viruses. But that does not mean we can afford to lower our guard. Vaccination is necessary to ensure that we remain protected against this highly unpredictable virus.” 

According to experts, another factor for declining COVID cases could be that besides COVID-19, there are four other types of corona viruses circulating in our environment that cause mild flu-like symptoms. So, some people may have got infections with milder virus in the past and developed a cross immunity, which gave them protection against COVID-19.

But these are all speculations and need research.

Overcoming vaccine hesitancy

Today, the question on everyone’s mind is do we really need a vaccine when cases are declining sharply? “Yes we do need a vaccine,” emphasises Dr. Agrawal. “The current decline in the number of cases in bigger cities may not be permanent.”  

He points to the recent outbreak in Manaus province of Brazil to illustrate his point. Manaus showed over 50% sero-positivity a few months back but currently it is struggling with a severe outbreak. “On the other hand, Israel which succeeded in vaccinating a large population could control the severe outbreak. We know that vaccines induce a stronger immune response which should last longer. However, recent data from South Africa has raised some concern on reduced effectiveness against some variants.”   

Read more: “Vaccines will help those who get it, as well as those who can’t”

Within a year of being hit by COVID-19— India reported its first case on Jan 30, 2020— the government initiated the country- wide vaccination drive with two vaccines, Covishield and Covaxin. Three crore healthcare workers and frontline workers are to be immunised in the first phase. 

The vaccines, so far, have not shown any severe side-effect. Both vaccines are considered safe and likely to cause standard side effects, which are seen generally in vaccination. Pain, swelling, redness, itching at the injection site, body ache, headache, fever, are some of the common side-effects listed by the companies. Though in some cases the vaccine may cause severe allergic reaction or other side-effects.

As per the government advisory, anybody can take the vaccine except pregnant and lactating women, patients on immunosuppressants, patients on blood thinners. But people with heart problems who take blood thinners such as aspirin can take the vaccine safely. It is advisable to share your health issues and medication with the vaccinator or a physician before taking the vaccine.       

After some initial hesitation, the two vaccines seem to have been accepted by doctors and other healthcare workers some of whom had earlier felt the government’s decision to  give Emergency Use Authorisation to the vaccines was rushed.

“Such decisions are well calibrated and taken after a thorough risk vs benefit evaluation,” says Dr Samiran Panda, a senior scientist, and head, department of Epidemiology, Indian Council of Medical Research, Delhi. “Right now, we need to quickly immunise people who are most vulnerable to catching infection or developing severe disease. It is people’s responsibility to take the vaccine when their turn comes. This is the only way to end this pandemic”.

Also read:

• All that we know about the COVID shots from the health ministry