Herd immunity against COVID-19? WHO says no signs of it yet
Experts have argued that if at least 60-70% of the population is to be exposed to the novel coronavirus and develops immunity, the rest of the population also will be protected against COVID-19, as it will be more difficult for the disease to spread to susceptible individuals.
Amid the COVID-19 pandemic, several experts have argued that only herd immunity could offer a lasting solution against the spread of the virus. But in its latest media briefing, the World Health Organisation said that it sees little signs of this happening so far.
Herd immunity is a concept in epidemiology that describes a state where a disease stops spreading in a population when enough people are immune to it. This can be because of mass-scale vaccination or because those people have been exposed to the virus and their immune systems have built antibodies to protect them from it.
The WHO's top emergencies expert Mike Ryans told a briefing on Friday that even if antibodies were effective, there was little sign that large numbers of people had developed them and were beginning to offer so-called "herd immunity" to the broader population.
"A lot of preliminary information coming to us right now would suggest quite a low percentage of population have seroconverted (to produce antibodies)," Ryans said.
"The expectation that ... the majority in society may have developed antibodies, the general evidence is pointing against that, so it may not solve the problem of governments."
The World Health Organization is also not sure whether the presence of antibodies in blood gives full protection against reinfection with the new coronavirus.
In South Korea, for instance, at least 116 people who had been initially cleared of COVID-19 were tested positive again. Scientists are yet to figure out the reason behind this.
Experts have argued that if at least 60-70% of the population is to be exposed to the novel coronavirus and develops immunity, the rest of the population also will be protected against the disease, as it will be more difficult for the disease to spread to susceptible individuals.
This has been a successful strategy in our fight against diseases such as measles and polio.
“...The problem with herd immunity is that it really hinges on vaccination. Without a vaccine, the only way to become immune to a disease is to get it and live through, which makes the strategy a whole lot more fatal,” says Gideon Meyerowitz-Katz, an epidemiologist in a column in The Guardian.
But vaccines are months, if not years, away.
The UK had initially announced creating herd immunity by allowing the virus to pass through the country’s population as a strategy to fight COVID-19. But the government abandoned the plan after studies by immunologists at Imperial College London and the London School of Hygiene and Tropical Medicine showed that around 30 per cent of hospitalised patients would require intensive care treatment. This meant that the country's health system could be overwhelmed.
What is an acceptable number of preventable deaths so that multinational corporations don't take too big a hit from the coronavirus pandemic?— Walker Bragman (@WalkerBragman) April 17, 2020
Talk of "herd immunity" and sending people back to work before a vaccine is developed is irresponsible, cruel, and outrageous.