What after lockdown? Developing herd immunity against Covid-19, and why India can pull it off

It would be a week since India stands placed under an unprecedented lockdown by the Narendra Modi government to prevent a Stage-3 outbreak of the Corona virus, which has claimed 34,000 lives and infected more than 7 lakh people around the world. What now? Will we be able to dodge the pandemic that has crippled the world’s healthcare system and devastated the global economy?

The answer lies in how we develop immunity against the disease. As mankind scrambles to find a vaccine against Covid-19, leading scientists are looking at means to acquire immunity against the deadly virus. Based on their deductions, India is in a unique position to not only safeguard its population but also lead the world towards herd immunity against the virus. Here’s why…   

Herd immunity: What does it mean? 

Herd immunity is when a sizeable population in a community develops immunity to a disease and breaks the chain of spread leading to its containment. It is kind of “indirect protection from an infectious disease”. Herd immunity can be acquired by either vaccination or from people who have previously recovered from the infection. Such a set of population is unlikely to transmit the disease and, therefore, reduces the possibility of those not immune to it in the community, contracting it.

Scientists consider a 55-70% infected population a safe bet for herd immunity to kick in. This means more the people recover from Corona virus, more they would contribute to building herd immunity and disrupt its contagious chain.

The trick is to reduce the number of people we are in contact with, so that we can drive down the number of contacts we infect, and herd immunity starts earlier. The sweet spot is when one infected person infects, on average, one or less than one other person

Professor Matthew Baylis

Matthew Baylis, a professor with the Institute of Infection, Veterinary and Ecological Sciences at Liverpool University tells Al Jazeera, “From an epidemiological point of view, the trick is to reduce the number of people we are in contact with, so that we can drive down the number of contacts we infect, and herd immunity starts earlier.” By reducing the number of people that one person infects – with social distancing measures such as closing schools, working from home, avoiding large gatherings and frequent hand washing – the point at which herd immunity kicks in can be lowered.

Germany is already mulling over ‘immunity certificates’ to people who have recovered from corona virus and “facilitate a proper transition into post-lockdown life”. The antibodies will indicate that the test participants have had the virus, have healed and are thereby ready to re-enter society and the workforce, says The Telegraph.

Covid-19 and its high reproduction number

In three months, the novel Corona virus has infected more than 7 lakh people across the world. The World Health Organisation had to declare it a pandemic with more than 100 countries coming under its influence. The virus is highly contagious because it has a higher R-naught (reproductive number) than the common flu. This has led to the spreading of this new strain of flu like a wildfire.

According to findings, the common flu has a basic reproductive number of 1.3, which essentially points to the average number of people an infected person will end up transmitting the virus to. Live Science reports, “The preliminary studies have estimated an R0 value for the new Corona virus to be between 2 and 3, which makes is three times as contagious as the common flu.”  This explains why it took 67 days for the first lakh to be infected with the novel Corona virus and only two days for the last set of 1 lakh.

This is also the reason why social distancing measures have been introduced to limit the spread of the virus. As Matthew Baylis adds to the viewpoint of gradual and safe build-up of herd immunity, “The sweet spot is when one infected person infects, on average, one or less than one other person.” 

The curious case of Indian sub-continent

There have been past observations on cross-reactivity between carriers of Dengue and influenza virus. India isn’t a case in isolation. If you look at our neighbours, we are resisting the virus, even if temporarily, in some way

Dr Ashok Panagariya

Even before India was placed under a complete lockdown, the cases of novel corona virus have been thankfully on the lower end of the global scale. This is in spite of the thousands of citizens who have been ferried home from Corona-infested countries like Iran and China, and millions of tourists who visited the country over the last three months since the scourge was first reported. There is a similar plot unfolding in most of the countries in the Indian subcontinent.

Consider this latest Corona update on the subcontinent:   

What we are witnessing in these countries stands in stark contrast to the spread of the infection in the European countries and the Americas where an unchecked upswing in the transmission of the novel Corona virus has left a trail of deaths and economic devastation. Professor Emeritus Neurology and Padma awardee, Dr Ashok Panagariya believes the low growth curve of the virus could be because of cross-immunity.

Enter cross-immunisation

An article by Babita Agarwal published in the Frontiers in Immunology states: Studies in humans and mouse models have clearly demonstrated that exposure or infection with one pathogen can induce and/or modify the immune response against another unrelated pathogen. This is what’s defined as heterologous immunity.

In layman’s terms, cross-immunity is a form of protection offered by immunity against one strain that partially or temporarily suppresses the transmission of another.

Another paper on cross-immunity archived on The National Center for Biotechnology Information, US, says, “Pathogens that invoke an immune response immediately after infection can also provide partial cross-protection against other strains of the same or closely related pathogens.”

A series of fortunate events

Dr Panagariya cites four incidents that occurred during the onset of the novel corona virus with Indians at the centre of it to build the premise of cross-immunity at work in the country.  

Case 1: For the first instance, he refers to the extraction of Indian citizens from Wuhan, the epicenter of the pandemic. “The first batch of 400 Indians was airlifted from Wuhan when the epidemic had started peaking in China. None of them were found to be Covid-19 positive,” says Dr Panagariya. 

Case 2: For his second citation, he quotes the widely reported incident of 18 Italian tourists who were travelling all over Rajasthan and were found to be infected. “All of them were carrying the Covid-19 virus and met 150 people during their stay in different cities of Rajasthan before they left for their country. None, except the driver who was with them throughout are reported to have contracted the disease,” says Dr Panagariya who shares a table on Rajasthan chief minister Ashok Gehlot’s advisory council.

Case 3: He quotes the case of 200 Indians who were extracted from Iran and were isolated in the desert district of Jaisalmer for 14 days as his third example. “They were tested for the virus. None came up positive,” he says. 

Case 4: As his final study, he draws a parallel between two cases: One that occurred in Italy, and the other in India. “In Italy, a woman carrying the virus ended up infecting scores of locals while attending the church.” Closer home, Singer Kanika Kapoor who flew in from London and skipped isolation was one of the attendants at the high-profile dinner in Uttar Pradesh last week. “What’s interesting to note is unlike in Italy where a single woman infected many, the singer who was diagnosed with Covid-19 remains the only one infected. All other attendants tested negative for Covod-19,” he sums up. Those who tested negative include, former chief minister of Rajasthan Vasundhara Raje who tweeted about the report and continues to remain in self-isolation.   

These cases, says Dr Panagariya, are an indicator that Indians are primed to fight this novel corona virus and stand to gain the most from grated social distancing and acquire herd immunity. “There have been past observations on cross-reactivity between carriers of Dengue and influenza virus. India isn’t a case in isolation. If you look at neighbouring countries, we are resisting the virus, even if temporarily, in some way,” he says. Sri Lanka has recorded just a single case of death from the so far.

What the stars foretell about containment of the novel corona virus. Read here  

Don’t forget to Gossip with God

Like his Liverpool counterpart, Dr Panagariya says herd immunity is inevitable to fight the disease. But we have to bring down the rate of spread by observing social distancing – avoiding social gatherings, working from home and protecting the elders. Until then his advice is to: Sleep well. Eat well. And, drink (water) well. “And, do not forget to gossip with God (pray and meditate) once a while to flush out the negativity and be hopeful about the future,” he says.