Science in the time of Corona: Part 2

Peter MolemanArticlesLeave a Comment

Translated by Rumia Bose

During the first lockdown in the Netherlands I wrote a blog about Science in the time of Corona. The emphasis lay on explaining the business of science, and that the establishing of facts took time that we did not have. At such moments you have to trust scientists and policy makers who are in charge.
We now know more than we did six months ago, making it much clearer what we need to have in place to contain the virus. The problems are of a different order. One problem is a number of vain scientists who get ahead of themselves or do not want to acknowledge the inaccuracy in their previous estimates. Whom can I believe? Experts are contradicting each other! Another problem is that virological and epidemiological problems are being overshadowed by psychological and social issues. A clear-headed view about the consequences of (the spread of) the virus is overshadowed by the fear of bankruptcy for business owners, or the need for partying and physical intimacy amongst the youth. Others dread loneliness and isolation. As for me, it is mainly the sense of insecurity which arises when I have little control over my own situation. Knowledge of the facts helps me keep this at bay.

What are the problems now?

The psychological and social consequences receive too little attention. The economic problems do receive attention, but the Dutch authorities do not clarify how their decisions are made. This arouses distrust in those who are affected adversely. But these aspects are not part of my expertise, so I will not go further into them. It is however perhaps of some use – also with regard to these other problems – if we have a better understanding of what is now known about the virus and its spread1“We’re not just fighting a pandemic; we’re fighting an infodemic,” says Tedros Adhanom Ghebreyesus, WHO’s director-general, Diseases TLI (2020): The COVID-19 infodemic. The Lancet Infectious Diseases 20:875.
This I can write about. Am I then a virologist or epidemiologist, is that my field of expertise? No. But my work for many years has for a large part been the reading of medical journals and judging the value of the articles. This I can also apply to a certain extent to virology and epidemiology.
My account is based on the work of other scientists, whose work I will refer to. There is however one scientist whom I will quote without checking the scientific articles on which he bases his statements: Anthony Fauci. And I follow Christian Drosten2@c_drosten on Twitter, because the same applies for him. The facts which they present can be relied upon to be sufficiently supported.

Is the virus more dangerous than previous influenza virussen?

There is no doubt about this. Arguments that some other flu epidemics have led to just as many deaths or ICU admissions can be disproved by the figures; these figures even downplay the severity of COVID-19. The most important confounding factor is the prevention paradox. A widespread imposition of lockdown and allied measures has limited the spread and severity of the pandemic. This range of measures has never been imposed for other flu epidemics. So the argument against these measures: “it is no worse than ordinary flu” is incorrect.

When are people contagious?

People are contagious before the first symptoms of COVID-19 appear. It is estimated that 20-50% of the infections are caused by people who are yet to show symptoms. The contagious period starts 1- 4 days before the first symptoms. The contagiousness decreases a week after the first symptoms, but can persist for a fortnight or even longer. The contagious period is probably shorter in people with milder symptoms, and only longer than 10 days for very severe cases.

What are the differences between the age groups?

With increasing age both the predisposition to getting infected and the severity of the illness after COVID-19 infection increase. This means that the chance that children in elementary school coming in contact with virus carriers will be infected is small, and the ensuing illness if they are infected is milder. In general: the younger the milder, the older the more severe. But, as the WHO says: “FACT: People of all ages can be infected by the COVID-19 virus.”

Can it become chronic?

There are reports of people who suffer for months from muscle pain, fatigue, problems with concentration, sometimes to an extreme degree. There have even been cases with damage to the cardiac muscle after having COVID-19. These problems have also been found in people with hardly any signs and symptoms at the start of the infection.
The virus enters the cell through receptors which are not only present in the lungs, but also on blood vessels and in other organs. It appears that in this way the virus can cause damage in various parts of the body. This may also help to explain chronic complaints as described above.
Some of the research shows that chronic effects appear in a large number of people, but there is not yet enough reliable data to be able to estimate the magnitude of this problem.

Who is most susceptible to the virus?

Age aside, people who have asthma, diabetes, cardiac disease and renal dysfunction more often suffer severe and deadly forms of the infection. Ongoing research into genetic predisposition, differences in the receptors[note]see above[/note] and differences in immune reactivity is aimed at getting to the bottom of age-related and other differences in susceptibility. This research may in the future provide data for identifying the most vulnerable people in advance. But we are not there yet.

What are the most important factors which help the spread of the virus?

The answer is quite simple. The main route of spread is through fluids carrying the virus, relayed directly or indirectly from one person’s mouth or nose to another’s. Keeping distance and wearing a face mask reduce the chance of direct transmission. Because these fluids are diluted and dispersed more easily outdoors, the chance of transmission is less than it is indoors. In addition, the more people that are present in an enclosed space, the greater the chance that there are infected people amongst them and that direct transmission takes place.
In general, the chance of coming into contact with an infected person is higher when there are more infected people in the population – of your country, your city, or your surroundings. The discussion about face masks has to do with this issue: they are of little value if the number of infected people is low. The higher the number of infected people, the more useful it is to wear a mask. It is estimated that in June- July, after the first wave had subsided, the number of infected people in The Netherlands was around 3,000. Now at the beginning of October, during the second wave, this is around 150,0003
The case for wearing face masks and maintaining physical distance is much stronger now than then. There is much ongoing research into spread via aerosols, the role of “superspreaders” and much more. There is not much point my going into this, because much of this remains unclear. And whatever their roles may turn out to be, they do not – with the current state of our knowledge – have much effect on the most important factors which help spread, or the corresponding measures.


When is the virus sufficiently under control that we do not have to be on our guard constantly, and we can go back to a more carefree life without increasing the risk of the next wave? For this we need to have developed sufficient immunity within the population.
In the beginning some experts thought that controlled exposure to the virus could build herd immunity. When a minimum of half the population were immune then the virus would not spread as quickly, and a lot less people would fall ill. This idea has been discarded entirely, partly as a result of the experience that when the ICUs were full and many people were dying, there still were relatively low rates of infection in the population; much less than 50%. Moreover, immunity has turned out to be short-lived. So a 50% rate of immunity within the population at any one moment will not be maintained for long. It remains unclear how the length of the immune period relates to the severity of illness in a person.
Immunity in a large section of the population must therefore be achieved with vaccination. A first effective and safe vaccine is expected to be available in limited quantities early in 2021, therefore only for a small number of people4Florian Krammer on Twitter: It will probably take till the end of 2021 before enough vaccine is available to provide for large numbers of people. Other vaccines are probably going to become available in the course of 2021 and in subsequent years.5A large number of vaccines are being developed. Because the various vaccines under development are very different in their mechanism of action, it may yet transpire that only some specific vaccines are of use for groups such as the elderly and children.
Fauci estimates that it will yet take another two years before we are that far. And he adds that the essential preventive measures till that time, and maybe longer, will still be “universal wearing of masks, avoiding crowds, keeping your distance, outdoor better than indoor, washing hands”.


It is unavoidable that I have not answered some essential questions. You can ask those questions below. I will try to reply to them and in some cases add the answer to the text of this blog.
I have not addressed all sorts of dubious claims which are in circulation. The WHO website dispels some of these myths:
In the time of Corona it is clear that you sometimes have to do unpleasant things in the interest of others and yourself.


Kampf G, Brüggemann Y, Kaba HEJ, Steinmann J, Pfaender S, Scheithauer S, et al. (2020): Potential sources, modes of transmission and effectiveness of prevention measures against SARS-CoV-2J Hosp Infect DOI: 10.1016/j.jhin.2020.09.022

Interview with Anthony Fauci, 23 september 2020,

Byrne AW, McEvoy D, Collins AB, Hunt K, Casey M, Barber A, et al. (2020): Inferred duration of infectious period of SARS-CoV-2: rapid scoping review and analysis of available evidence for asymptomatic and symptomatic COVID-19 cases. BMJ Open 10:e039856.

Pitzer VE, Cohen T (2020): Household studies provide key insights on the transmission of, and susceptibility to, SARS-CoV-2. The Lancet Infectious Diseases 20:1103–1104.

Sun K, Wang W, Gao L, Wang Y, Luo K, Ren L, et al. (2020): Transmission heterogeneities, kinetics, and controllability of SARS-CoV-2. medRxiv: The Preprint Server for Health Sciences DOI: 10.1101/2020.08.09.20171132

Badr HS, Du H, Marshall M, Dong E, Squire MM, Gardner LM (2020): Association between mobility patterns and COVID-19 transmission in the USA: a mathematical modelling study. The Lancet Infectious Diseases 0. DOI: 10.1016/S1473-3099(20)30553-3

Krammer F (2020): SARS-CoV-2 vaccines in development. Nature :1–16. DOI: 10.1038/s41586-020-2798-3

Cevik M, Marcus J, Buckee C, Smith T (2020): SARS-CoV-2 Transmission Dynamics Should Inform Policy [Internet]. Rochester, NY, Social Science Research Network. DOI: 10.2139/ssrn.3692807

A recent webinar of experts about “long-COVID”:

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