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In a time without sport, the scores still tell a compelling story

Many people were surprised to see the high number of Covid-19 cases in Germany while the mortality rate crucially remains very low at 0.6%.  In the same way, South Korea has kept a very low mortality of 1.4%, in contrast with the United kingdom at 4.9%, France 5.3%, Spain 7.3% and Italy 10%. 

These figures raise many questions about the nature of the Coronavirus – the way the virus is spread and the most effective way to contain the pandemic. 

In this article, we will try to understand more about this virus, looking at evidence from China, South Korea, Italy, Germany and the UK. 

The story begins on 31st December 2019, with China notifying the WHO of an outbreak of a viral pneumonia causing high mortality in Wuhan.  Subsequent reports from many other countries repeat this message, prompting the WHO to declare a pandemic on 11th March 2020.

How does the Coronavirus actually work? The science bit

Covid-19 is a new variant of the well-known corona (“crown-like”) viruses, belonging to the beta coronavirus.  It is classified as an RNA virus, implying Ribonucleic acid material encased in protein.  The virus is very tiny (several times smaller than a bacterium) and is not capable of independent living.  It has to live in another organism (a host), and gain access to the host cells to obtain energy and protein supplies necessary for survival and replication.  Outside the host cells, the virus stays dormant, shows no signs of living, does not replicate and usually perishes within few hours.

Covid-19 is zoonotic infection that spreads between humans and animals.  Early genomic sequencing revealed the virus is 96% identical to Bat SARS, putting the blame on bats as the source of the pandemic.

The infection spreads through virus-laden respiratory droplets person-to-person after coughing, sneezing or talking.  The critical distance is 6 feet (1.8 metres) and the virus could remain in the atmosphere for up to 5 hours.  Infection is also spread on contaminated surfaces and notably stays longer on plastic (72 hours.)

People could start spreading the infection even before having symptoms, during the incubation period, which is usually 5 to 6 days but may extend to 14 days.

Airborne infection, so far, has been ruled out in most of the epidemiological reports; there is also no evidence to suggest faecal-oral spread as a driver of infection; however, the virus has been recovered in faeces of a few cases.

Covid-19 is killed at temperatures of 26°C and over, making many to speculate that the pandemic will die out as we approach the hot summer months.  This is currently contradicted by the spread of the virus in hot countries, such as Algeria, Senegal and Singapore.

We have learned from Wuhan that 80% of cases have no symptoms or mild self-limiting upper respiratory tract symptoms, 13.8% present as severe pneumonia requiring hospital care, while 6.1% required mechanical ventilation in intensive care units.

The virus launches a severe attack on the lung cells resulting in what is described as cytokine storm.  This is characterised by the extensive release of inflammatory messengers causing severe damage to the host’s lung.  This frequently progresses to acute respiratory distress syndrome (ARDS) leading to septic shock and respiratory failure.  However, multiple organ failure is the ultimate cause of death in these severe cases.

Some good news: Covid-19, SARS and MERS

Covid-19 usually spreads easily and quickly, resulting in the sustained transmission of infection, but causes relatively mild disease with relatively low overall mortality (0.5 to 3%) compared to other members of the coronavirus family such as SARS and MERS.

(You may remember the pandemic of Severe Acute Respiratory Syndrome (SARS) in 2002/03 resulting in a high mortality of around 9.6%, whilst Middle East Respiratory Syndrome (MERS) in 2012 produced a very high mortality rate of 34.5%.)

How does the pandemic grow?

During the initiation phase, we expect a few sporadic cases, often in small clusters.  In the acceleration phase, transmission of infection increases to a very high level until a peak is reached.  Post peak, the number of new cases falls significantly.

The source of infection in many countries is people returning home from abroad.  Infection passes on to their contacts.  During the acceleration phase, infection spreads fast through the community, often while the source of the infection remains unclear.

What is happening now?

China has reached the peak of the epidemic and is currently having low numbers of new cases reported, while Italy, for example, is struggling badly with the acceleration phase.

It is not difficult to understand the high rate of infectivity during the acceleration phase – with perhaps one case passing the infection to 10 healthy people.  This ‘transmission rate’ of 10 is expected to fall to less than one after the peak.

We can describe the epidemic in China and Italy as “explosive,” starting in both countries with very high number of cases, many of them severe requiring critical care.  In Italy, the number of cases went beyond the country’s healthcare capacity, resulting in a very high mortality rate of 10%.

Who has got it right? China, South Korea, Germany, UK?

In any epidemic we need to identify factors that could reduce the incidence of severe disease and thus the overall mortality.  Experience in China tells of the huge effort to diagnose cases early and apply stringent quarantine measures to reduce the spread of the infection.  In the Wuhan area, there were 1,800 epidemiology teams on the ground, each comprising 5 members.

South Korea was also highly praised for being proactive.  They invented a reliable test and sanctioned its widespread use to find cases early, and then applied draconian public health measures.  These helped South Korea keep a very low mortality rate of 1.4%.

The epidemic pattern in Germany and the United Kingdom appear pretty similar.  Germany’s first case was reported on 28th January, while in the UK, the first two cases were reported on 31st of that month.  This was followed by a few sporadic cases in both countries until early March.

Germany then started to see the rapid escalation of cases, reaching over a thousand for few days after 10th March.  The UK had its first death on 5th March, after which there was rapid escalation of cases.

However, there are significant differences in the population demographic affected in those respective countries.  The outbreak in Germany happened largely in young fit individuals returning from skiing trips.  As you would expect, most of these had mild disease with no further consequence, resulting in low mortality rate.

Again, Germany applied widespread early testing, including on those with mild symptoms. They are performing 160,000 tests per week, even more than South Korea’s 105,000.  This has resulted in the early identification of cases.  And this, together with effective therapeutic intervention, has kept the mortality rate very low.

On the other hand, in the UK, conducting fewer tests has reduced the chances of finding more confirmed cases.  (You can assume that, for every confirmed case, there are 10 cases who have not been tested.)  Such low levels of testing incorrectly reduce the “advertised” number of confirmed cases in the UK – whilst the higher mortality rate continues.

What can we do?

You can raise the public immunity against Covid-19 by a massive vaccination programme or you can allow the infection to spread in the community.  Unfortunately, the vaccine will not be available for another 12-18 months.  Having the disease is not a viable option in view of our current knowledge about severity of the disease and the consequent loss of life.  Therefore, I am pleased that the UK has gone back on its plan to use herd immunity.

However, apart from the above empirical evidence from around the world, unfortunately it is too early to draw conclusions on the outcome of the battle against Covid-19.  All we can say is that the countries of the world must share their ideas and any solutions.

 

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