Only about 10% of the global population has antibodies against the coronavirus infection, WHO experts said last month.
Herd immunity has been touted as a way to slow the spread of the novel coronavirus and control the ongoing COVID-19 pandemic. Also called community immunity, herd immunity occurs when a large part of the population is immune to a specific disease through infection or vaccination. When this happens, person-to-person transmission of the disease becomes less likely, thus helping control the pandemic/epidemic. When herd immunity is achieved, the most vulnerable members of the population (babies, pregnant women, and immunocompromised people) are protected because the germ will not be able to "find" those susceptible individuals.
But currently, we are nowhere close to having herd immunity levels needed to stop the coronavirus, said World Health Organisation (WHO) officials. They have also advised against any attempts to achieve herd immunity or to hope that it will eventually save people. "Herd immunity or natural population immunity is not an option. Let's put our energy, focus, workforce, actions into what works," IANS quoted Maria Van Kerkhove, WHO's Covid-19 Technical Lead, as saying.
Citing ICMR's second sero-survey, Union Health Minister Harsh Vardhan on Sunday also said that India is still far from achieving herd immunity against the novel coronavirus. He cautioned that the sero-survey report should not create a sense of complacency among the people as the ICMR is actively investigating and researching reports of reinfection.
The first sero-survey conducted by the Indian Council of Medical Research (ICMR) in May had revealed that the nationwide prevalence of novel coronavirus infection was only 0.73 per cent. "Even the soon-to-be-released second sero-survey's indications are that we are far from having achieved any kind of herd immunity which necessitates that all of us should continue following Covid-appropriate behaviour," the minister said during an interaction with his social media followers on 'Sunday Samvaad' platform.
Although the number of reinfection cases is negligible at this moment, he noted that "the government is fully seized of the importance of the matter."
Growing evidence suggests that COVID-19 infection not only impacts the lungs but other organs too, especially cardiovascular and renal. According to Vardhan, the Union Health Ministry has set up committees of experts to look into these facets of the infection. In addition, states and Union Territories have been advised to lower the prices of COVID tests, he added.
For diseases that spread easily, like COVID-19, a large percentage of the population will need to be immune against the disease to reach herd immunity. Recent reports suggested that herd immunity may be achieved when as little as 50% of the population is immune, as against earlier estimates that at least 70% of the population would need immunity.
However, only about 10% of the global population has antibodies against the coronavirus infection, WHO experts said last month. This means we're a long way from herd immunity via antibodies. Besides, it is also not clear how strong these antibodies are, how long the protection lasts, and how it may vary between people.
Therefore, the focus should be on "what we can acutely do now to suppress transmission and not live in hope of herd immunity being our salvation," Dr. Mike Ryan, the executive director of the WHO Health Emergencies Programme, said during a media briefing last month.
Some experts also warned that trying to reach herd immunity without a vaccine would be a disastrous pandemic response strategy. Without a vaccine, the only route to reach herd immunity is through infection, and many people infected with SARS-CoV-2 means millions would die.
