London: The chief scientist at the World Health Organization estimates that about 50 per cent to 60 per cent of the population will need to be immune to the coronavirus for there to be any protective "herd immunity" effect.
Herd immunity is usually achieved through vaccination and occurs when most of a population is immune to a disease, blocking its continued spread.
During a social media event on Friday, Dr. Soumya Swaminathan said that studies done from some countries hit hard by COVID-19 show that about 5 per cent to 10 per cent of people now have antibodies, though in some countries, it has been as high as 20 per cent.
She says: "As there are waves of this infection going through countries, people are going to develop antibodies and those people will hopefully be immune for sometime so they will also act as barriers and brakes to the spread." Other experts have estimated that as much as 70 per cent to 80 per cent of the population need to have antibodies before there is any herd immunity effect.
In the pandemic's earlier stages, countries including Britain proposed achieving herd immunity as an outbreak response strategy. But Swaminathan pointed out that achieving this effect with a vaccine is much safer than letting the virus rip through the population.
She says that to achieve herd immunity through natural infection, you need to have several waves and you will see the morbidity and mortality that we see now.