What Exactly Is Herd Immunity and Will It Help in the Fight Against Coronavirus?

This article originally appeared on VICE Indonesia.

As most of Europe implemented strict social distancing and quarantine policies in late February, one of the United Kingdom’s approaches to tackle COVID-19 was to allow the virus to spread naturally so that the population can build “herd immunity.” Unsurprisingly, this sparked panic among its citizens.

UK Prime Minister Boris Johnson, who himself is now under intensive care due COVID-19, eventually dropped the strategy, which was endorsed by the government’s top scientists, after Imperial College London researchers revealed that the policy would overwhelm the country’s healthcare system.

But how exactly does herd immunity work?

When we recover from a disease, our memory cells “remember” the disease, which enables our bodies to fight it if we come into contact with it again. Vaccines create this memory without requiring us to become infected in the first place.

When a new disease like COVID-19 emerges and spreads through a population, enough people could develop an immune memory that could cause the disease to stop spreading, even if some people are not yet immune.

Herd immunity requires a virus to claim lives of people who didn’t have a chance to build immunity against it. Scientists estimated that 50 to 67 percent of a population must get infected and recover for herd immunity to be a success. But it does not always work, so some experts are concerned about governments considering this strategy.

Dr. Tifauzia Tyassuma, Executive Director of the University of Indonesia’s Center for Clinical Epidemiology & Evidence-Based Medicine, has raised concerns that the Indonesian government may be leaning toward allowing nature to run its course until all Indonesians achieve herd immunity. This, she believes, is evidenced by Indonesia’s readiness to take reactive measures against existing cases while neglecting preventive measures.

A population can achieve herd immunity through the use of vaccines or naturally, by allowing people to contract the virus and recover. With estimations that viable vaccines are still roughly a year away, countries like the UK, the Netherlands, and Sweden, have floated the idea of implementing a herd immunity approach.

Dutch Prime Minister Mark Rutte faced international backlash in mid-March when he included herd immunity in the Netherlands’ anti-coronavirus strategy.

“As we wait for a vaccine or medicine, we can slow down the virus spreading and at the same time build up herd immunity in a controlled manner,” Rutte said at a coronavirus briefing in March. Rutte later clarified that building herd immunity would amplify the impact of other anti-coronavirus measures like the lockdown and social distancing.

University of Indonesia Epidemiologist Dr. Tri Wahyono believes that more than 16 million of Indonesia's 271 million population would die before everyone else is immune, as scientists are still unsure how long such immunity lasts.

“Allowing the population to become infected will result in immunity. But immunity to the SARS-CoV-2 (COVID-19) is not guaranteed to be long-term, it will last a year at most. We cannot have this happening on a yearly basis,” Wahyono told local media.

Dradjad Wibowo, senior economist at the Institute for Development of Economics and Finance, pointed out the human rights implications of letting large chunks of a population get sick.

“Where would we treat these tens of millions of patients? A herd immunity approach goes against humanity, fairness, and civility, so we need to forget this approach and prevent it from becoming policy. Too many people will die,” Dradjad told local media.

Indonesia currently has 2,491 cases of COVID-19, but experts warn that the number is likely much higher due to the size of the population and lack of testing. Indonesia's hospitals are now overwhelmed with patients. If Indonesia were to follow the path of herd immunity, its healthcare system would likely collapse.