Herd Immunity Is A Reckless Coronavirus Strategy: Health Experts
Herd immunity has divided health experts, with some saying it's a risky and reckless approach to managing the coronavirus outbreak.
Varying public health responses to the COVID-19 pandemic have emerged as countries try to “flatten the curve” of the virus and ease the burden on health systems.
Australian Health Policy Advisor, Professor Bill Bowtell, says governments have three choices when tackling the virus; to contain infections in advance, as it mounts or, controversially, to let it spread.
“Do you stop or contain the infections in advance of them spreading, as is the case of Taiwan, or Korea or Singapore, or do you wait and do very little and have a massive engulfment, as we have seen in Italy, France, now Spain -- and the U.S., it has to be said,” Bowtell told ABC’s Q&A program on Monday.
“Or apparently, in the United Kingdom, do you adopt another policy, based on unproven assumptions, and effectively make a scientific experiment of your citizens and see how far a virus can spread, and see what happens?”
The latter approach is known as ‘herd immunity’ -- it formed part of Britain’s initial response to the pandemic. The U.K. government has since backtracked after complaints this strategy to COVID-19 is unethical and dangerous.
Despite this, the Netherlands' has indicated it will embrace a similar strategy in its attempt to control the distribution of COVID-19 “among groups that are least at risk”.
Herd immunity is said to work by protecting at-risk groups, such as the elderly, by surrounding them with those who have developed resistance to the virus.
Epidemiologist Professor Hassan Vally said herd immunity is generally developed through vaccination “of a specified proportion of the population.”
“The key issue here is that for disease to spread, an infectious agent needs to find susceptible people to infect. If it can’t, the chain of infection is interrupted and the amount of disease in the population falls,” Vally said.
“The key benefit is that those who are most vulnerable to severe disease and who cannot get the vaccination are in fact protected by the rest of the community who do get vaccinated.”
Vally said a similar scenario can sometimes occur when enough people contract and recover from an infection.
“This is in fact how epidemics die out naturally; that is, when there are not enough susceptible people to infect,” Vally said.
What Happens When There Isn't A Vaccine?
But there is currently no vaccine available for COVID-19.
“[This coronavirus] is not like flu. It’s not like other viruses and diseases where we have vaccination,” Australia's Deputy Chief Medical Officer Dr Paul Kelly said.
There is no herd immunity. Everyone is susceptible to this virus in Australia.
The Australian government has so far introduced a ban on public gatherings of more than 500 people and indoor gatherings of more than 100, along with an indefinite ban on all overseas travel.
In a detailed address on the country's response to the pandemic on Wednesday, Scott Morrison announced strict new measures and urged the public to practice social distancing.
The PM said schools would remain open, based on current health advice.
In Britain, herd immunity formed part of the government's early response to the pandemic. It initially opted to introduce slower social distancing than other countries, to protect at-risk groups from contact with others, and to allow COVID-19 to spread through the rest of the population.
According to U.K PM Boris Johnson’s chief scientific adviser, Sir Patrick Vallance, between 60 and 70 per cent of the British population would need to be infected to build herd immunity.
“We think this virus is likely to be one that comes year on year … like a seasonal virus,” Vallance said on Saturday.
“Communities will become immune to it and that’s going to be an important part of controlling this longer term.”
But Vally is among the epidemiologists who have cautioned against such a response when dealing with a new virus.
More than 200 scientists also signed an open letter criticising Vallance's views on the virus and urged stronger controls to protect the U.K. population. Johnson's government was quick to respond and deny herd immunity was part of the strategy.
“It is a very risky strategy to allow a disease that is known to have severe outcomes to just run its course in a large group of the population,” Vally said.
By doing this you are in fact putting many people at risk of severe illness.
Professor Nikoali Petrovsky, from Flinders University, agreed that attempting to let COVID-19 “run rampant” is an economic decision that could have “catastrophic consequences”.
“The problem is no one knows how many people in the U.K. would need to be infected first before we might see development of herd immunity,” Petrovsky said.
Like Vallance’s projections, Petrovsky said typically this takes at least 70 per cent of the population to be infected, which would represent at least 50 million people in the U.K.
“With an estimated case fatality rate of one to three per cent, this would involve the deaths of 500 thousand to 1.5 million U.K. residents,” Petrovsky said.
Bowtell said the approach is " an extraordinarily reckless thing to do."
The U.K. has since tightened the social distancing measures imposed on the public -- including stopping "non-essential contact" with other people and avoiding public places.
It comes as researchers at Imperial College released a report that found the attempts to "mitigate" or slow -- but not necessarily "suppress" -- the virus would overwhelm U.K. hospitals “many times over” and lead to about 250,000 deaths.
But while it’s considered a risky strategy, infectious diseases epidemiologist Allen Cheng believes it may well be the “ultimate outcome”.
“It's hard to get enough situational awareness to know when things might need to be tightened up,” he said.