COVID-19 Update
Information about COVID-19 has expanded exponentially over the last few months. Along with information, we are seeing both misinformation and increasingly disinformation. It remains our opinion that COVID-19 can best be understood in terms of the disease and the epidemic.
COVID-19 is a very serious disease in specific circumstances. In addition to older males with other illness we are increasingly appreciating that the disease is more serious in health care workers (because of viral load) and in association with obesity and poverty. Studies in the UK and US also show a significantly higher incidence in people from Black, Asian and Ethnic Minority (BAME) backgrounds. It is unclear yet the relative contribution of genetic, economic and social factors but it is already clear that COVID-19 will amplify social inequality. Poverty is associated with both higher infection rates and worse outcomes. One simple way of thinking about this process is that COVID-19 is generally worse as biological age increases. It is important to appreciate that individuals do not age biologically at the same rate. We can control some factors which influence the biological ageing process. Obesity, poor diet, lack of exercise and metabolic syndrome make people old before their time and these conditions significantly worsen outlook in COVID-19.
We have a greater understanding of the immune reactions which are associated with more severe disease. In particular, we are developing a greater understanding of the inflammatory reactions around blood vessels which may lead to blood clotting and organ damage. The early drug treatments are beginning to report. One of the first peer-reviewed trials published in the Lancet was from Hong Kong. This trial showed benefits for drug treatment in mild to moderate disease as defined by reduction in symptoms, viral shedding and hospital stay. Which patients need treatment, what will be the optimal treatment and whether suppressing the virus early will reduce more severe complications later needs further research.
Early in this process we explained the importance of having an anchor against which to compare risk. We used influenza data as this is a condition with which most people are familiar. Unfortunately, the influenza comparison has become ingrained in the political narrative. In order to appreciate this issue, it helps again to revert to the distinction between the disease and the epidemic.
There is clearly more to illness severity than the mortality rate but this is one measure of severity. The case fatality rate of seasonal influenza is approximately 0.1%. The current crude fatality rate in Hong Kong of COVID-19 is 0.39% and in Singapore it is 0.01%. Hong Kong and Singapore both had excellent preparedness plans and instituted widespread testing, isolation and quarantine. They are both more likely to recognize asymptomatic or mildly symptomatic young people and it is logical to assume that they are closer to the true infection rate than countries which have allowed the epidemic to burn without testing. Some antibody studies are now beginning to be reported. There are valid criticisms around these early studies. We have analyzed the difficulty of antibody studies here. We explained early in this process that disease severity is typically downgraded as epidemics evolve and this is happening with COVID-19. Final mortality rates are likely to vary across populations. This may be influenced by genetic, social and economic factors that influence the health of populations. The efficiency of health systems and the application of public health measures will also influence mortality on a national and regional level. Current evidence would suggest an infection mortality rate of COVID-19 of <0.5%.
To say that COVID-19 is an illness which will have a fatality rate much lower than initially feared is not to reduce the importance of the global health challenge. It is a statement based upon evolving evidence. We have explained throughout this process that the mortality in population terms will be determined by the epidemic, not by the impact of the disease on a case by case basis. Using SARS as an example, SARS had a case fatality rate of around 11%. That makes it >100x more dangerous than influenza on a case by case basis, yet it killed less than 1,000 people worldwide. COVID-19 is much less serious than SARS on a case by case basis but characteristics of this illness mean that it is a more serious epidemic. The SARS-COV-2 virus is both able to infect people without symptoms and is more infectious earlier in the illness which means that it is better at travelling than SARS was. It also creates an illness which by its nature overwhelms health systems by filling up intensive care units. This can increase deaths from other causes.
COVID-19 is a significant global health threat because of the nature and size of the epidemic. Fortunately, just as we have acquired information about the disease process in hospitals, we have accumulated a greater understanding of the factors which allow disease control within a community context. We have good evidence that appropriate public health interventions focusing on social distancing are able to control the epidemic. As predicted in our last email, the epidemic curves in Europe have increasingly come under control and some countries are beginning to relax existing restrictions. The response to the relaxation of the differing public health strategies will give vital information about the optimal management of the epidemic as countries balance the human and economic impact of the disease. Systems which have focused on the concept of testing, case identification, isolation and quarantine of contacts have been most effective in suppressing pressure to health systems. This strategy will be more achievable the lower the case numbers and it is likely that testing and isolation of infected individuals and contacts will continue to be a key component of epidemic control.
The epidemic has currently been suppressed in Hong Kong and life here is slowly beginning to return to a new normal. Control of the local epidemic is a testament to both preparedness and the world class systems and expertise in public health in our city. OT&P have been fully functional throughout this process. We have performed more than 2000 tests for COVID-19 including more than 1400 blood tests for antibodies as part of our study in collaboration with the University of Hong Kong. The first phase of the study is due to complete over the next couple of weeks.
Anxiety has for the most part settled in Hong Kong and there is now an opportunity for some reflection. Whether it is the experience of home schooling revealing the challenge of building strong nurturing relationships with children or a reduction in overseas travel and business lunches leaving time for that frequently postponed medical check-up. COVID-19 has been a Black Swan event and there is no question that it will act as a significant disruptor. The political narrative tends to focus on threats but as we all adapt to the new normal it is important to focus on the many opportunities that this disruption will bring. Now is a time to focus on health. Health is a state of physical, psychological and social well-being, not the absence of disease. It is a positive construct and there has never been a better time to invest in a healthier future.
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