Journal club - Faculty of Public Health, Khon Kaen University
March 2020 (2563)

One needs to know more about Covid-19 before predicting a horror scenario

The general public should not be frightened by alarming scenarios while facts and conditions which will further influence the spread of the COVID-19 are still not known

Experience throughout the evolution probably induces mankind to be much more afraid about infectious diseases, than other health threads, for instance, those causing non-communicable diseases, such as cardiovascular diseases or cancer. This attitude is reinforced in times when a real threatening epidemy of an infectious disease arises, even more, when the infective agent spreading was unknown before and no straightaway treatment is available and prevention through vaccination is not yet developed. These events are kept in the public memory. However, it is one of the curses of mankind that such events happen from time to time more or less regularly. Who does not remember the Severe Acute Respiratory Syndrome (SARS) epidemy in the years 2002 to 2003, or more recently the Middle Eastern Syndrome (MERS), the latter occurring in the years 2012 to 2015. Now, while writing this contribution, the world is experiencing another pandemic, as declared from the World Health Organization, with another nasty particle of the coronavirus type and termed coronavirus disease 2019 (COVID-19) or SARS-CoV-2 (1). Public reactions vary either to try to downgrade the thread or come up with announcements having the potential to cause panic[1]. As a timely reaction, a professor of epidemiology joined hands with a professor in mathematics, and three infectious disease specialists, from well recommended institutions within the USA pointed towards a number of still unknown facts and conditions which influence the spread of the disease (1). The content of their Editorial should be kept in mind when attempting to officially predict now what will happen in the future. The authors cautioned not just to look at frightening numbers of so far infected cases and how fast the disease spreads throughout the world, but also to take into consideration ‘what questions for prevention’ still need to be answered as far as the ‘new coronavirus outbreak’ is concerned.

So far, it is known from the Chinese Centre of Disease Control, that the majority of cases with 80.9% are mild, while 13.8% are severe and 4.4% is critical. For an estimation of how severe the 

spread of an infective agent is, the reproductive number (R₀) should be considered. R₀ gives an assumption of how many people might be infected by a case as a secondary case. In the situation of China, the number is given as 2.5 to 2.9 and the fatality rate[2] as 2.3%. Those numbers are frightening when compared to one of the most deadly pandemics of modern times, the so-called Spanish flu, which happened at the end of the first World War, originated from the USA, transmitted from the American soldiers shipped to Europe and spread further on to the rest of the world. All in all, it is estimated that about 17 to 50 million people died. The estimate exceeds those being killed throughout the “great war”. The R₀ was assumed to be about 1.8 and the fatality rate 1 to 2%. However, is it justified to frighten an already alarmed population even more, with prediction based on the experience made formerly?

Further transmission

Presently it is not known yet whether the transmission will remain the same, will even increase or decline. That depends on how the immune system of men will finally react to the virus and what preventive measures will be taken. Variables not known yet are, for how long the virus will spread, what about the ‘numbers of infective particles are released’ from an infected person and what about the sustainability of the virus within the different environments of a given region. An important human factor is that one person might be unfortunately a “superspreader” while others are much less dangerous for their surroundings. Another important aspect is how the society reacts to preventive measures imposed on the population by the authorities and what are the decisions of the authorities. The president of the USA just cut the connections to Europe, while a number of European countries within the European Union more or less closed their borders, while one of the most populated central European countries, still refuse to do so. Population density within a given area and behavior within a defined society also plays an important role. So, for instance, the movements of the population within a defined place and the need of traveling to work for some distances.

Influence of preventive measures

Preventive measures also might have an impact. It will take still some time for the development of a vaccine. Momentarily strictly observing hygienic suggestions, like hand washing might help as well as wearing a face mask, whether this will have an impact still remains to be seen. To resort to drastic measures such as closing down big cities, preventing from leaving and entering into certain provinces or even countries and suggesting to resort voluntarily to a 14 days quarantine are thought to curb the further spread of the disease. To get an idea about the influence of these items and variables mentioned above might finally be of value to work for mathematical models which will help to forecast which impact the epidemy will have on the population further on and when it can be expected that it will fade out.