Herd immunity and why social distancing won’t prevent the spread of coronavirus

Ever since the World Health Organisation upgraded its classification of the global COVID-19 outbreak to a “pandemic” earlier this week, countries around the world have sought to ramp up their “social distancing” measures.

Italy’s national quarantine – first announced by Prime Minister Giuseppe Conte on Monday – has been progressively tightened. Ireland’s Prime Minister has announced today that the country’s schools, colleges, and childcare facilities will be shut down from tomorrow.

Now, across the United States, hospitals and large public gatherings – including high profile sports games – are being suspended and postponed. President Donald Trump’s response to the crisis up to this point has been widely criticised for its complacency. Critics say that social distancing and emergency measures were introduced too slowly while the virus spread aggressively throughout the US.

Some commentators have also argued that the UK, only just beginning to implement more stringent measures, ought to have acted quicker. With pressure mounting on the government to implement similar measures as Ireland, however, Downing Street has stuck to its gradualist position. The government instead said that it will remain guided by the advice of its leading scientists and experts in its response to the virus.

Prime Minister Boris Johnson – flanked by his chief medical and scientific advisers –  announced after a COBRA meeting this afternoon that the UK has begun the “Delay” phase of its coronavirus strategy. It will not be immediately suspending large public gatherings or, following Ireland, closing schools – but it has not ruled out making such decisions in the near future.

The country’s Chief Medical Adviser, Chris Whitty, asked that anyone who has a cough that is continuous or a temperature should stay at home for seven days and self-isolate – that is the period it takes for a person to no longer be infectious. The logic behind this is to protect vulnerable elderly people, lower the peak of the epidemic, and push the peak back until a later time when the NHS is better able to respond to increased strain.

In the UK’s approach there is a strong emphasis upon public responsibility above state coercion in leading the response to the outbreak.

Part of the scientific response is to emphasise the limitations of “social distancing itself”. Patrick Vallance, the government’s Chief Scientific Adviser, explained at the press conference today that “it’s not possible to stop everybody getting it and it’s also not desirable”.

Instead, what is needed is the development of a “herd immunity” among the population to guard against later seasonal outbreaks of COVID-19 in the future.

The UK’s high ranking health professionals believe that their response has been appropriate and is more likely to be effective in the long run. The UK’s Deputy Chief Medical Officer, Jenny Harries told the BBC today that “The really important thing about some of these social distancing measures…is to make sure that they go in at the right time.”

In other words, timing is key. While initiating these measures too late runs the risk of increasing the numbers of those infected, and with it the scale of the pandemic, going too early is also potentially damaging. There is a balance to be struck between premature urgency and sheer complacency.

Pull the trigger too late and it leads to a larger health crisis – but do it too soon, and you could create great social disruption and economic recession. Both can induce a sense of panic and crisis, and both can worsen the spread and impact of the disease.

“There’s a disbenefit to acting (too) quickly as well as to not acting quickly” says Sian Griffiths, Director of the School of Public Health and Primary Care at the Centre for Health and Development. What the UK needs to do is “minimise the damage to the economy and maximise the containment phase”.

In pursuit of this goal, what matters is the quality of the government intervention as much as the quantity. President Donald Trump’s announcement of a comprehensive ban on foreign nationals travelling from the Eurozone to the US, for instance, has frightened world markets without obviously remedying the spread of the infection in the country at large.

The efficacy of the Irish approach of closing schools is also debated. Keith Neal, Professor of the Epidemiology of Infectious Diseases at the University of Nottingham, has warned that “closing schools has a number of known consequences” which “might make the epidemic or the ability to manage the consequences worse”.

These consequences include the reduction in the number of frontline health workers, as people are forced to look after their children at home, and an increased risk to vulnerable grandparents providing childcare. Instead, a logical next step, Sian Griffiths suggests, would be to introduce bans on large-scale public meetings at events such as sports fixtures.

One size does not fit all – the ways in which different countries’ economies are structured, their varying demographic trends and their cultural behaviours, combined with how people travel, move, and interact within them, mean that tailored responses are required.

This makes it problematic to compare the UK’s situation to that in Italy. The average age of the Italian population is older than that of the UK by about five years, while the initially undetected spread of the virus within hospitals in the north of the country has exacerbated the health crisis.

The Italian government has also had to introduce a strict national quarantine in order “to encourage people to abide by the restrictions” and mitigate “increasing strain on healthcare facilities”, explains Elisabetta Groppelli, a lecturer in Global Health at St. George’s University of London.

Several experts have suggested that the public health messaging in the UK has probably been more effective, meaning that the type of large increases in case numbers and fatalities which have taken place in Italy have not yet occurred in the UK.

Public engagement is a key element to any effective government response – the most stringent of state-led measures can only work if citizens also take restrictions seriously.

Still, there is evidence that these types of strict quarantine measures can be successful in slowing the rise in case numbers, at least in the short term.  A recent research paper, published by a collaborative research team led by Shengjie Lai at the University of Southampton, may support tough actions by the state.

This research has found that what it calls “non-pharmaceutical interventions” – which range from state-imposed travel bans to self-isolating – have had a significant impact in bringing about declining case numbers in China.

Epidemiologists who have reviewed this research have said that, while the data sets and modelling upon which it is based are not perfect, the study suggests that when lockdown measures are implemented in a timely and effective way, the spread of the coronavirus can be significantly reduced.

But real concerns remain about the long-term viability of social distancing measures. The reasons for this wariness are not only epidemiological but social and political. The conditions in Wuhan which have allowed for the intensive control and coercion of the population are linked to the capacities of the Chinese surveillance state.

There are doubts about whether the authoritarian measures put in place to control the spread in Hubei – where people have in some cases been forcibly tested, taken from their homes, and made to obey a strict quarantine – could last for long in a liberal democracy such as Italy. In Britain, the delicate balance between individual freedom and state authority will have to be carefully guarded.

There are even concerns that it might not ultimately be sustainable in China itself. This is the view of François Balloux at University College London, who points out that China-style containment strategies “come at a great cost to individuals, communities, and the economy.” You can’t have Beijing’s control procedures without Beijing’s politics.

Balloux adds that while China has enjoyed success in “controlling the pandemic, for now”, it is “not sustainable to maintain such a nationwide lockdown for very long.” Populations become fatigued with social restrictions and economies become burdened by recession caused by economic slowdown. Italy, for example, is now set to fall into a recession.

Social distancing, in the end, is also much more a case of crisis management than crisis prevention. It is about buying time for public services to respond – it cannot protect populations from COVID-19 indefinitely.

Given that the virus is moving throughout the globe and that it could be as long as eighteen months before a vaccine is available, there is no guarantee that a quarantined population will not become infected again once social restrictions are removed.

Paul Hunter, Professor of Medicine at the University of East Anglia, explains that “COVID-19 is already spreading globally”, meaning that “when the restrictions in Italy are eased there may still be a large number of cases in nearby countries that could lead to spread back in Italy.”

This combination of factors makes it unlikely that such strict quarantine measures will be introduced in the UK, at least not  right away and not over a long period of time. Where early cases in Italy were concentrated in a single region – in the north of the country – the UK already has cases distributed across its regions, Hunter points out. The potential for a tight quarantine to limit geographical spread is therefore reduced.

There are cultural and political as much as economic and epidemiological considerations at play in the coronavirus crisis. The UK government’s response could be said to represent a carefully examined attempt to balance the scientific evidence with political possibilities. It tries to find a way of combining authority, technocracy, and humane sensitivity. Time will tell how successful it will be in battling the coming storm.