To block the advance of the coronavirus which we can’t directly attack because we haven’t yet found a vaccination or a treatment, all we can do is to apply a “scorched earth” policy, no matter what the cost.
Of course, we won’t burn our crops and cottages like the Russians fleeing before Napoleon, but we will stay at home after closing our schools and factories, and halting our trains and airplanes, to protect ourselves while creating a vacuum around the invisible enemy: this is the only way to break the chains of virus transmission.
In his first speech to the French nation on the COVID-19 pandemic on March 16, President Emmanuel Macron declared that France was "at war". But in face of the “invisible enemy" of the coronavirus, he didn’t elaborate on the underlying strategy.
In the absence of a vaccination we have no preventative defence and, with no treatment, we have no way to launch any kind of counter-attack. All we can do is to hide ourselves (confinement) to try to stay out of reach of the enemy.
But, just as in a real war, we have an intelligence service, to detect the enemy’s presence and movements in the form of medical tests. This intelligence is essential to help us to apply the only practical strategy: a scorched earth policy to block the enemy without direct combat.
We have to avoid contact with the enemy, in the knowledge that the virus needs human cells to survive, reproduce and continue its advance. This scorched earth strategy includes the wearing of masks, precautions such as handwashing, social distancing, the isolation of suspected or confirmed cases of infection, and the confinement of the whole population.
Importance of tests
In this specific strategy against the coronavirus, tests allowing us to locate the enemy play an essential role because they help to apply confinement in the right place, at the right moment and in the right way to halt the virus as efficiently as possible, while reducing to a minimum the economic and social cost of confinement.
The head of the World Health Organization (WHO) insisted at the start of the pandemic that above all we had to "test, test, test" because “we cannot stop this pandemic if we don’t know who is infected” as "you cannot fight a fire blindfolded."
The logic is to test to identify the virus and isolate its carriers to prevent the illness from spreading. In practice, testing must firstly cover people who have symptoms of the illness and all those who have been in contact with them. This extension of the field of testing takes account of the ease and speed with which the virus spreads. Tracking procedures are used which draw on modern technologies of communication and surveillance. The complete strategy, in fact, can be summarised as "test, trace, isolate."
Time is a crucial factor in this strategy on locating the virus (testing), determining the range of possible infections (tracking) and isolating the people concerned (quarantine). The strategy needed to be applied right from the start of the pandemic, with massive and immediate testing as soon as the first cases were identified.
A delay of a few days means the deaths of thousands of people, as shown by comparing results in countries that reacted fast (South Korea, Taiwan, Germany) and those who were slower (France, the UK, the US). A further price to be paid for a slow reaction is that confinement has to be larger-scale, stricter and longer to avoid a second wave of the epidemic after the first peak. It’s like fighting a fire: because the fire was initially allowed to spread, it’s now harder to put it out.
The future is worrisome because, as we can’t test the whole population, we have to concentrate on those who show symptoms of the illness, leaving aside those who have had contact with the virus but show few or no symptoms. These people make up the majority of cases of infection and can be very contagious.
This difficulty in determining the field of contagion is reinforced and compounded by our ignorance of the possible modes of contagion, notably ambient air. To stop the pandemic, it would be helpful to identify people who have been in contact with the virus without having become sick, and so supposedly become immune.
The most widely used test up to now is the virological polymerase chain reaction (PCR) test, used to detect the presence of coronavirus by taking samples from the nose and throat.
Another kind of testing needs to be increased: serological tests to detect the presence of antibodies in the blood of people who have had contact with the coronavirus and who are therefore logically immune to COVID-19 thanks to these antibodies.
These serological tests are complementary to the virological tests as they exclusively can provide information allowing other approaches in the fight against COVID-19 to be identified:
- Determining through a representative sample the degree of spread of the coronavirus in a given population, which would allow better preparation and implementation of deconfinement, as France is preparing to do from 11 May.
- Following the progress of a population towards collective immunity, reached when 60% to 70% of the population has the antibodies which protect against COVID-19.
- On the individual level, the virological test allows identification of those who are ill in order to protect the rest of society. But the serological test allows identification of those who are not ill, especially those who are immunised to restart society and the economy. I’ve underlined the difference in approach between these two types of tests in two recent articles in The Geopolitics: How to Prevent COVID-19 From Paralysing the World’s Economy and Exiting Coronavirus Confinement Is a Shot in the Dark Without Immunity Testing published respectively on 27 March and 2 April.
Concrete examples of the application of serological tests
Serological tests have been applied in three concrete cases which could serve as examples:
- Chile has issued immunity certificates to show that their holders can return to work and serve their country without risk of infecting their fellow citizens.
- The French company Veolia has tested its 50,000 employees to evaluate their immunity and to better guarantee their security when work restarts.
- The Emirates airline carried out a COVID-19 blood test on its passengers just before embarkment.
The potential for using serological tests is immense. It is the start of the concept of the passport or certificate of immunity; this would allow deconfinement on solid, rational grounds for whole towns and regions by identifying immunised people who can resume their activities without putting anyone in danger, as the mayor of Paris Anne Hidalgo has suggested.
Overcoming the objections
There are two objections, concerning the precision and reliability of this type of test to detect the antibodies after an infection by the coronavirus, and the uncertainty over the period during which the antibodies can provide protection against a new infection.
On the first point, rapid progress is being made on accuracy, (avoiding false negatives) and specificity (avoiding false positives) in the serological tests to detect antibodies. In the near future, if it’s not already the case, the results of these tests will have margins of error close to zero.
On the second point, the WHO has cautioned that it’s not certain that antibodies present at a given moment will be able to protect against a new infection by the same virus in the future. This WHO warning opened a debate on the possibility of the same person catching the same virus in a relatively short period. Such a hypothesis on the absence of immunisation would lead to catastrophic and irrational results (pandemic without end and impossibility of producing a vaccination). It’s “very difficult to conceive” of such a scenario, as Dr Marc Gozlan said in Le Monde. Dr Sanjay Gupta, Chief Medical Correspondent for CNN, also said about this alleged absence of immunisation, "absence of evidence is not evidence of absence."
The WHO based its warning on a few cases observed in China and South Korea. There may have been a problem in the precision and reliability of the tests used before and after the sickness with insufficient accuracy and/or specificity.
But European countries have already seen tens or hundreds of thousands of people who have recovered from COVID-19, and so have the opportunity to study the existence and length of immunity among those who were ill, at a time when the precision and reliability of the tests have greatly improved.
Even if many uncertainties remain over the development of the COVID-19 pandemic and its costs to humanity, it already seems that in the absence of a vaccination, medical tests will continue to occupy a fundamental place in the scorched earth strategy that states have put in place.
There will be much greater adoption of serological tests after the problems concerning those tests are resolved, which will probably be done in a not too distant future. Some countries will need to learn from the past to avoid the same error of a lack of preparation for the serological tests, which are crucial to finally leaving confinement and restarting the world economy