The origin of the term 'epidemic' is attributed to Hippocrates in about 400BCE. It was the title of one of the books attributed to him which described the occurrence of illness in relation to the seasons. Since then, epidemics have played an important role in determining human history; think, for example, of the Black Death, the Plague, and cholera. They seem to arise from nowhere, cause death and devastation, and then mysteriously disappear while the population waits in fear of their return.
One such, which you will have seen referred to in the press recently, was the 1918/19 influenza pandemic, pandemic being the term to describe an infective epidemic that threatens most of the world's population. This killed more people than had died in the war that preceded it, many victims being relatively young, in contrast to the usual effect of influenza.
My father, a child at the time, wrote: 'We children were kept out of public places while it lasted and none of us got it. I remember my father saying that he had seen the hall porter at the hospital and the porter had said "I think I’ve got a touch of the Russian," and he was dead the next day'. Others were less fortunate, both my wife's and my maternal grandmothers dying of pneumonia during the epidemic while in their 30s. Some survivors developed encephalitis and later Parkinson's disease. That was a virulent epidemic.
My generation, born before widespread immunisation became available through the NHS, was very familiar with epidemics, as measles, German measles, mumps and chicken pox came and went each year. We also knew that when we got these illnesses, we were unlikely to get them again; we developed immunity.
The most feared epidemic disease was poliomyelitis, and we all knew of someone who caught it and was paralysed or even died. Another was smallpox, commonly fatal. Both of these have largely been eliminated by mass immunisation, though some pockets of polio still exist in the Middle East. But there were some diseases that we also feared and were not epidemic; they were endemic, always around and available to be caught. The most common endemic disease was tuberculosis and anyone who got this had a 50% risk of dying. Public health measures coupled with meticulous use of anti-tuberculosis drugs has almost eliminated the risk of infection in the UK, but it remains a worldwide problem in the poorer world.
You will note that success in reducing risks from most of these diseases has come not from finding cures but rather from public health measures and the amazing success of immunisation – the use of vaccines. This has a long history and has always had a few opponents but is undoubtedly the greatest success story of medicine over the modern era. Production of vaccines has received a huge boost from the use of modern molecular genetic science, such that it is now proving possible to think in terms of producing a vaccine for widespread use within a year of the discovery of a new epidemic microbe.
This all begs the questions, where do these epidemics come from and what gives them their energy to travel around? The current coronavirus (Covid-19) episode is providing us with a daily lesson in understanding what is going on:
The extraordinary speed at which the virus was identified as new, using the latest advances in molecular genetics. This method of identifying the virus has enabled both reliable means of tracking its spread and, also, the hope of producing candidate vaccines quickly, even perhaps to be available for testing on humans within a year.
The ability to identify the source of the outbreak as a jump by a virus from another species to humans, leading to a way of reducing risks of future such episodes by food hygiene measures.
A test of apparently very repressive measures to limit spread by prohibiting movement of large numbers of the population in affected cities. My first thought on hearing of the outbreak had been 'thank goodness this has occurred in China – no other country has the means to restrict its people's behaviour in this way'. At present, it seems that these measures have been reasonably effective in reducing spread and perhaps the duration of the epidemic in China.
The importance of international cooperation, as directed by WHO. Like climate change, the other major existential threat, action needs to be coordinated across the world and politicians need to accept advice from the experts. Two obvious failures have occurred already – the initial brief attempt to conceal the outbreak in China and the denials in Iran on apparently religious grounds. The latter has been highlighted by the Minister of Health himself falling victim to the infection, which must cause some soul-searching. Attempts to conceal are positively harmful. Of great concern to me is the politicisation of the epidemic in USA, which is threatening a very serious problem of loss of control there over the next few weeks.
The importance of authoritative public information. In the UK, our Government was originally curiously silent, leaving us with two sources – expert comments from public health officials and inexpert, sometimes alarmist, comments in the media. As the epidemic reaches these shores, our cooperation with public health advice is now essential to limit its spread and possibly duration; that advice must be clearly endorsed by ministers, but side by side with health experts to give them the credibility they have regrettably lost. Solo appearances by the Prime Minister will remain unconvincing.
It is helpful in trying to understand epidemics to look at them from the point of view of the causative organism, in this case a mutated form of a well-known common cold virus, unrelated to influenza. These organisms cannot exist alone; they require living cells in which to thrive and reproduce.
However, they are subject to the same evolutionary pressures as all living things. They need to spread from one animal or plant to another to ensure survival of the species, so they need a means of spreading. It is to their advantage to spread widely, so contact or transmission by air, water or food is helpful. In general, they do not live unless in a living cell and thus shed cells are infective for a relatively short time, probably a few days in the case of Covid-19. It is also to the virus's advantage if it does not kill its host and some of the most successful viruses cause little or no problem to their host.
So, when watching the evolution of the Covid-19 story, I paid particular attention to the daily reports of spread and mortality and it quickly became apparent that this was not as virulent as some other recent new viral outbreaks known as SARS and MERS, but that it spread more easily. It also became apparent that it could spread from person to person before symptoms had developed. This is a characteristic that is worrying, since it reduces our ability to control it by detecting and isolating people with early symptoms. Conversely, it is very much to the virus's advantage. Cautiously, I reasoned that this would spread widely round the world but kill relatively few of us in proportion to the numbers infected.
My next concern was to ask who was dying from the infection, and as reports filtered out it appeared that this is not in any way like the 1919 influenza which killed lots of fit young people. Reassuringly (save for me!), this is like most influenza epidemics in that it proves fatal mainly to the elderly and those with chronic heart and lung disease and diabetes. However, unlike influenza it is not yet preventable by immunisation.
Evidence from China showed that mortality among those infected was almost nil in children but rose to 15% among people over 80 years of age. But there is also evidence that mortality is strongly related to the available healthcare facilities in relation to the numbers falling ill.
As time passes, it is apparent that Covid-19 infection is being widely distributed by travel around the world, but spread is being controlled reasonably effectively in countries with good public health systems. Such countries are in the minority worldwide and so further spread seems inevitable as it takes hold in less well provided places such as Africa, India, the United States and the Middle East. It is thus necessary for us all to take sensible precautions now.
What can we do? At present in Scotland we need to do three things: first, attend to personal hygiene by washing our hands thoroughly with soap and water after going out shopping or to any public places, avoiding putting our hands to our faces, using tissues when sneezing or coughing, and avoiding hand shaking and facial contact; second, reduce exposure to others in public places, transport and events; third, if we develop symptoms such as cough, fever or breathlessness, we should stay at home and contact our doctors or call 111 for advice if it does not settle quickly. Do not visit the surgery or A&E. The available masks are of little value in protecting us from infection but may reduce the risk of passing it on if we are infected, though some healthcare workers need appropriate high-quality respirators fitted as part of their protective equipment.
There are two benefits of this personal behaviour; to reduce one's own risk and to help control the spread of the infection among others, so the more that comply, the smaller will be the epidemic.
Now cases have occurred in the UK, there will soon be big decisions for politicians, guided by experts, on closing schools, cancellation of events such as football matches, concerts and conferences. The worst of these will be whether to cancel international events such as the Olympics and Edinburgh Festival, but by then increased knowledge of the virulence of the virus will act as a guide.
At present, it seems that infection is associated with death in between 0.5 and 2% of those with symptoms, but these figures vary considerably depending on local problems in recording cases and the availability of healthcare. It is now clear that the young are relatively resistant to it and those of us over 70 need to take special care of ourselves. It is likely that those with symptoms are themselves the tip of an iceberg of very mild infection and so data on incidence of the disease may underestimate the numbers infected.
It is useful to bear in mind data from China, where the epidemic seems to have peaked within about two months, and where healthcare facilities were often insufficient initially. At the time of writing, there have been approximately 80,000 diagnosed cases and 2,900 deaths, but this is in a population of 1.42 billion. Thus, so far in China, six per 100,000 have fallen ill, of whom 3.6% have died. On the Diamond Princess, 3,700 people were exposed to the virus and 706 were infected – 19%. Of these, six have died or 1.6% of those exposed, and this among what is likely to have been a predominantly elderly and susceptible population.
Our chances in Scotland of catching it and of dying are likely to be considerably less than those in China or the cruise ship, and this is reassuring. However, our personal risks of catching Covid-19 depend on two factors within our control. First, the precautions we take and second, the numbers of infected people we are exposed to. The more careful we and those we meet are, the smaller our risk.
So, for several weeks I have been washing my hands frequently, avoiding crowded places, shopping at quieter times, and practising smiling and saying namaste when I meet people. I'm afraid, being 81 and having heart disease, I have decided not to use my ticket for the Scotland-France rugby match this weekend but to watch it on television. And a trip abroad is out of the question until things settle down.
There are analogies with climate change. Coordinated, expert-led action by international bodies is essential and we need to heed advice from our governments. We are fortunate in the UK to have a well-prepared NHS and extremely well-qualified Chief Medical Officers. In addition, all of us need to do what we reasonably can to reduce our personal risks and thus overstressing the NHS. And we should start now; don't wait until a technical definition of pandemic is satisfied.