Controlling the global spread of Covid-19

Based on articles from The Economist and The Guardian

Covid-19 continues to spread globally: Outbreaks in Italy and Iran, along with a large one in South Korea, have convinced many epidemiologists that attempts to keep the virus contained within China have run their course; it will now spread from second countries to third countries and on around the world.

As of February 27th, cases had been reported in 50 countries.

Financial markets have suffered their worst falls since 2008. The spread of the disease to South Korea, Iran and Italy caused a massive sell-off on February 24th. The next day prices fell further when the Centres for Disease Control and Prevention warned Americans to prepare for the virus.

As of the morning of February 27th, stock markets had fallen by 8% in America, 7.4% in Europe and 6.2% in Asia over the past seven days.

The industries, commodities and securities that are most sensitive to global growth, cross-border commerce and densely packed public spaces got whacked particularly hard, with the prices of oil and shares in airlines, cruise-ship owners, casinos and hotel companies all tumbling.

As the virus inevitably spreads the aim of public-health policy, whether at the city, national or global scale, is to flatten the curve that reflects the rate of new infections.

The benefits of this policy are that it is easier for health-care systems to deal with the disease if the people infected do not all turn up at the same time. Better treatment means fewer deaths; more time allows treatments to be improved. Second, the total number of infections throughout the course of the epidemic can be lower. Thirdly, there should be less reason for people to descend into panic mode.

To flatten the curve you must slow the spread. The virus appears to be transmitted primarily through virus-filled droplets that infected people cough or sneeze into the air. Transmission is largely reduced by hygiene and physical barriers together with “social distancing,” measures already routinely used to control the spread of any influenza virus.

Although their initial response was slow the huge efforts made in China have reduced the growth rate dramatically. Outside Hubei, cities which pre-emptively imposed travel restrictions and bans on large gatherings have seen flatter epidemic curves; the measure that made the biggest difference was closing down public transport.

But few countries will be able to impose controls as strict as China’s. Something that is acceptable in one country might result in barely any compliance, or even mass protests in another.

What is needed over the next few months is that governments and people neither dismiss the risks nor panic.

To this end The Guardian today published a simple note on busting the coronavirus myths; the truth about the protective value of face masks and how easy it is to catch Covid-19

Claim: ‘It is no more dangerous than winter flu’

Many individuals who get coronavirus will experience nothing worse than seasonal flu symptoms, but the overall profile of the disease, including its mortality rate, looks more serious. At the start of an outbreak the apparent mortality rate can be an overestimate if a lot of mild cases are being missed. But this week, a WHO expert suggested that this has not been the case with Covid-19. Bruce Aylward, who led an international mission to China to learn about the virus and the country’s response, said the evidence did not suggest that we were only seeing the tip of the iceberg. If borne out by further testing, this could mean that current estimates of a roughly 1% fatality rate are accurate. This would make Covid-19 about 10 times more deadly than seasonal flu, which is estimated to kill between 290,000 and 650,000 people a year globally.

Claim: ‘It only kills the elderly, so younger people can relax’

Most people who are not elderly and do not have underlying health conditions will not become critically ill from Covid-19. But the illness still has a higher chance of leading to serious respiratory symptoms than seasonal flu and there are other at-risk groups – health workers, for instance, are more vulnerable because they are likely to have higher exposure to the virus. The actions that young, healthy people take, including reporting symptoms and following quarantine instructions, will have an important role in protecting the most vulnerable in society and in shaping the overall trajectory of the outbreak.

Claim: ‘Face masks don’t work’

Wearing a face mask is not an iron clad guarantee that you won’t get sick – viruses can also transmit through the eyes and tiny viral particles, known as aerosols, can still penetrate masks. However, masks are effective at capturing droplets, which is the main transmission route of coronavirus, and some studies have estimated a roughly five-fold protection versus no barrier. If you are likely to be in close contact with someone infected, a mask cuts the chance of the disease being passed on. If you’re just walking around town and not in close contact with others, wearing a mask is unlikely to make any difference.

Claim: ‘You need to be with an infected person for 10 minutes’

For flu, some hospital guidelines define exposure as being within six feet of an infected person who sneezes or coughs for 10 minutes or longer. However, it is possible to be infected with shorter interactions or even by picking the virus up from contaminated surfaces, although this is thought to be a less common route of transmission.

Claim: ‘A vaccine could be ready within a few months’

Scientists were quick out of the gates in beginning development of a vaccine for the new coronavirus, helped by the early release of the genetic sequence by Chinese researchers. The development of a viable vaccine continues apace, with several teams now testing candidates in animal experiments. However, the incremental trials required before a commercial vaccine could be rolled out are still a lengthy undertaking – and an essential one to ensure that even rare side-effects are spotted. A commercially available vaccine within a year would be quick.

Claim: ‘If a pandemic is declared, there is nothing more we can do to stop the spread’

A pandemic is defined as worldwide spread of a new disease – but the exact threshold for declaring one is quite vague. In practice, the actions being taken would not change whether or not a pandemic is declared. Containment measures are not simply about eliminating the disease altogether. Delaying the onset of an outbreak or decreasing the peak is crucial in allowing health systems to cope with a sudden influx of patients.

, , ,