Pune: The term’ herd immunity system’ has been popping up since last few days after Sweden was observed to have been following this strategy to combat coronavirus disease (COVID-19). There has been discussion on how impactful would it be if India too followed the system to fight against the pandemic.
Experts like Urmila Kulkarni Kale, Dr Avinash Bhondwe, AC Mishra and Samiran Panda broke it down for the readers. They were unanimous in their opinion -- it won’t work for Indians.
What is herd immunity?
Herd immunity is referred to as community immunity. Individuals acquire resistance towards a virus either through infection or vaccination.
When significantly large population, say over 60 per cent, becomes immune to infection, then such individuals provide indirect protection to other individuals in the society who cannot develop immunity due to various other complications. Herd immunity is based on this principle.
“The immune individuals, in turn, help to break the chain of transmission of disease. In this process, the probability of non-immune individuals coming into contact with infections decreases significantly. The net outcome of herd immunity results in controlling the spread of the virus,” said Urmila Kulkarni Kale, Information Scientist at Bioinformatics Centre of Savitribai Phule Pune University.
Explaining its application, Kale said, “Classic examples of controlling disease through herd immunity are smallpox and measles, where vaccinations are available. Reduction in vaccination of measles in some parts of the world has resulted in its resurgence. Therefore, the World Health Organisation (WHO) has extended timeline to eliminate measles by 2023 in the South-East Asian region.”
Herd immunity may not work in many cases. For example, in the case of Titanus, which is a bacterial infection, long term immunity can not be achieved even after taking the vaccine. Even for influenza, herd immunity will only provide temporary protection as influenza viruses evolve rapidly and seasonal outbreaks are caused by different strains of influenza, Kale explained.
COVID - can’t say!
“In the context of COVID-19 or SARS-COV2, we still don’t know the extent of the immune response. It hasn’t been characterised completely yet. This is the first of its kind situation. Many have got infected, some have recovered as their immune system has been successful in fighting and eliminating the virus and thereby these individuals have gained immunity against it. Now the question is how long they will remain immune to COVID-19 virus -- that isn’t known yet,” Kale added.
Kale noted that studies are underway to unfold details of the disease and the immune response to it.
Life risk matters
“Herd immunity can be followed when there is lower life risk’”, stated Dr Avinash Bhondwe.
Dr Bhondwe is the president of the India Medical Association (IMA) Maharashtra. He believes that it’s a little far-fetched vision for India.
“Usually, in less dangerous infections like measles, mumps, we can follow this strategy where the death rate is less. But in the case of COVID-19 where the spread is faster, even if we achieve herd immunity, the death rate, in this case, will be high. We have 1.3 billion population, even if 10 per cent get infected it will be huge,” said Bhondwe.
“In this present condition of COVID-19, we shouldn’t think about herd immunity at all,” said Bhondwe.
He also stated that with practising compulsory social and physical distancing, hygiene maintenance, and lockdown, the country has been able to contain the spread.
‘Suicidal for India’
A country like Sweden can afford it-- where there is a small population and adequate health infrastructure to support the population, stated former director of Pune-based National Institute of Virology (NIV) AC Mishra.
“A country like India, where the number of hospitals is very few, infrastructure is poor, many hospitals are full, fewer ventilator facilities so we can go for it. For us, it will become suicidal,” said Mishra.
“The purpose of lockdown was to get some breathing time to build the health infrastructure and fewer people getting affected by COVID-19. After lockdown is over, the transmission of the virus can increase, for which we are preparing now,” he added. The current policy of having a lockdown and imposing restriction in red zoned are appropriate, stated Mishra.
Swine Flu comparison
In 2009, when Swine Flu broke out, it spread faster as like COVID-19 then. “But pathogenicity (disruption of internal organs) was less compared to COVID-19, which is more severe. Hospitalisation duration was less; hence impact was low too. But in the case of COVID-19, the virus is surviving for 10-12 days or more. This has caused more threats, so deaths are also higher here,” Mishra explained.
‘It is doable’
ICMR-National AIDS Research Institute (NARI) director Samiran Panda stated that herd immunity is doable. Still, it has certain challenges associated with it.
“It cannot be followed exactly how Sweden is doing; Indian reality is different. It should be dealt with case-by-case considering the locality--whether densely populated or not, state and socio-cultural demographics here,” said Panda.
“By ensuring proper health system in place, adequate health services to a vulnerable lot like senior citizens and those having co-morbidities. Also maintaining social distancing. If such complications and challenges are addressed, then there stays a possibility,” he said.
Senior citizens at risk
The director emphasised on the need to keep senior citizens out of this process-- they shouldn’t be exposed to the herd immunity system.
“Complications and sufferings are much more among elderly people,” he added.
A large part of India’s population consists of youth. “Death rate related to COVID-19 isn’t the same in all age groups-- it is more observed among the elderly and those having co-morbidity irrespective of their age. So even if an adult who is a smoker, his/her lung capacity is compromised, or a person is diabetic, underwent kidney transplant or HIV affected it can be complicated. We need to ensure care and support systems for them. Sans these people, there is a larger section in the society who can still undergo herd immunity system,” said the director.
He added herd immunity is not about everybody having immunity but the majority having it. Only then young adults can get infected and develop resistance against it.
Practice all precautions
Panda also stated that even if herd immunity system is followed, the practice of social distancing and maintaining hygiene cannot be neglected. Behavioural modifications that have been followed in the past several weeks shouldn’t be undone.
He also mentioned that India is currently trying to draw all kinds of models to combat the situation, scientists have an approach of balanced mix and match which will benefit most downtrodden and poor section, densely populated areas of the society and also keeping in mind the health of the senior citizens.
Kale had also stated that herd immunity model needs to be tested and validated in smaller localities, especially the ones which are declared green zone by taking adequate measures.