Herd immunity is usually achieved through vaccination and occurs when most of a population is immune to a disease, blocking its continued spread.

In a social media live event organised by the World Health Organisation from Geneva, the scientist said that more waves of the infection would be required to get to a stage of natural immunity, reports Hindustan Times.

Therefore, she warned, that at least for the next year or so, the world needs to be “geared up” to do everything possible to keep the novel coronavirus at bay while scientists work on vaccines.

Meanwhile, therapeutics will help keep death rates low and allow people to get on with their lives.

“For this concept of herd immunity, you need 50 to 60 per cent of the population to have this immunity to be actually able to break those chains of transmission,” explained Swaminathan.

“That’s much easier to do with a vaccine; we can achieve it faster and without people getting sick and dying. So, it is much better to do it that way, to achieve herd immunity through natural infection. We would have several waves [of infection] and unfortunately also the mortality that we see,” she said.

She added, “Over a period of time, people will start developing natural immunity. We know now from the studies that have been done in many of the affected countries that usually between 5 to 10 per cent of the population has developed antibodies. In some places it’s been higher than that, up to 20 per cent.

“As there are waves of this infection going through countries, people are going to develop antibodies and those people will be hopefully immune for some time and so they will also act as barriers and brakes to the spread of this infection,” said Swaminathan, a paediatrician from India and a globally-recognised researcher on tuberculosis and HIV.

The scientist, who was addressing a range of questions on coronavirus vaccines and therapeutics, said that for the foreseeable future, it is important to be focussed on doing the “right thing” such as public health measures that are known to work while the world waits for a vaccine.

“Even if the clinical trials are successful and we have a couple of vaccines by the end of this year, we still need the hundreds of billions of doses, which will take time,” she said.