A Question of Scale

Staff in healthcare are worried about the novel coronavirus responsible for the worldwide pandemic. Many of the public also express similar concerns and with the media emphasis on the impact on healthcare and the daily count of thousands of cases and deaths, it is hardly surprising.

However, as I have continued to remind everyone who is prepared to listen, as all the data from every country continues to show, most people will not experience any disease with this virus and those that do, for the vast majority it will be a mild illness.

This virus is behaving as every other respiratory virus that infects man. Respiratory viruses cause a spectrum of disease from very mild, as in a head cold to the very serious, as in influenza. There are viruses that are commonly associated with the former and rhinovirus is perhaps the commonest associated with a simple cold while the influenza syndrome is classically caused by the Influenza A virus with its capacity to undergo minor annual drifts or sporadic major shifts, capable of introducing a new pandemic as in 2009, when a new strain of H1N1 emerged.

What is more, with all these viruses, some individuals will become infected and be capable of spreading infection to others but will have no symptoms themselves – asymptomatic infection. Why some individuals get an asymptomatic infection and others a severe infection leading to death is not clear. Certainly, we can identify those individuals who are at increased risk and these risk groups are now currently well known to anyone who has taken an interest in the new pandemic coronavirus.

Every year, normally in our winter season, we experience flu related admissions to our hospitals. Numbers vary and every year, we see excess deaths associated with such admissions. Most such deaths are in the elderly and those with multiple co-morbidities. The same groups that are noted as being at higher risk with the novel coronavirus. However, every year (but in much smaller numbers than we are experiencing now) the respiratory viruses will cause serious disease or death in younger people. These will not normally make the national press unless they have celebrity status and the particular association with a respiratory virus may not be noted, often being described as pneumonia.

This is why I have included the image of the Gin and Tonic – primarily because I want you to think about the ice-cube, floating in the liquid. Assume one of those ice cubes popping its head out of the liquid is the normal sum and range of all the respiratory viral infections occurring during our winter season. Those at the peak will be the serious infections, while nearer the liquid and in greater number are the minor infections.

With this novel coronavirus, we have to assume everyone in the world is non-immune and at risk of infection, so instead of an ice-cube, think of an iceberg. Everything is now on a massive scale but in proportion to what we expect with other respiratory viruses. This means, however, that we see the massive numbers presenting to hospital with serious infection.

As we have seen from images first in China and subsequently in Italy and Spain, these numbers are huge and challenging for our ITU’s and hospital services generally. But remember, at least 80% of cases are managed in the community and this is the bulk of that massive iceberg that we see floating in that sea. The iceberg analogy continues, however. As we all know, the bulk of the iceberg is beneath the water and this is the rest of the population. While figures vary from country to country because of the different testing strategies, most people remain well. While numbers of deaths and serious disease is horrific, it remains a very small percentage of the total population being studied.

What we do not have a clear idea of yet is the number of that remaining population who remain at risk and non-immune to those who have had an asymptomatic infection. It is becoming increasingly clear from recent informal reports from Italy that asymptomatic infection appears to be much more common than was initially suspected from China. Access to antibody tests for serological surveys of our populations going forward will offer some interesting insights over the likelihood or otherwise of any ongoing risk to the remainder of the unaffected populations.

In seeking to offer an understanding of scale, what must continue to be emphasised is that as individuals, we must not let our guard down. As both the Prime Minister and the Prince of Wales have illustrated, it is impossible to know who will acquire the virus and how badly or not it will affect us. None of us should be blasé about the risks and should ensure we continue to follow all the best advice we can around social distancing, hygiene practices and, for the caring professions, appropriate use of personal protective equipment when in close proximity to our patients.