A scientist’s opinion: Interview with Dr. Marc Wathelet about SARS-CoV

We speak with Dr. Marc Wathelet, Molecular Biologist, Coronavirus specialist, about the differences between SARS-CoV-1 and SARS-CoV-2


Taking your early, alarming statements and the precautionary principle in medicine into consideration, in your opinion why does the WHO insist on its statement on the transmission competence of SARS-CoV-2? Do you envisage a different (international) governmental approach soon?

Dr Marc Wathelet ESMH ScientistWell, the WHO did admit in its report after the fact-finding mission in China that aerosol transmission was a possibility requiring further studies, but indeed it has not updated its recommendations to include how to prevent this type of transmission. It seems that we must reevaluate our international approach to fighting global infectious diseases, because our current approach has been slow and ineffective.


Can immunity to SARS-CoV-2 be developed after being infected by it, and can it mutate to an extent that it becomes resistant to the vaccination that is currently being developed? Also, do you think that chloroquine therapy could be an effective possible way of treatment for SARS-CoV-2?

Some form of immunity is developed in people who have been infected by the new coronavirus, with the production of detectable antibodies. This is important in order to track transmission of the infection through the population and better understand its dynamics. However, it is not a given that this immunity will be robust, if we use other already known coronaviruses as a guide. The immunity naturally developed in individuals may not be strong enough to provide collective immunity, but it will provide maintained immunity to changes in SARS-CoV-2 brought about by genetic and antigenic drift. Induced immunity, through vaccination, is also not a given: some previous coronavirus vaccines in animals protect against the disease while others exacerbate it, and so the testing of vaccines is very important. Chloroquine therapy is very promising, although early results are still to be confirmed by several studies currently being conducted. Hydroxychloroquine is the most active form, as it targets the host cell rather than the viral component. As it is the host cell being targeted, it is much more difficult for the virus to mutate resistance to the therapy.

It is not a given, however, that this immunity will be robust if known human coronaviruses are a guide. Natural immunity against human coronaviruses may not be strong enough to provide collective immunity, but the individuals who do develop a good natural immunity will maintain immunity against genetic and antigenic drift from SARS-CoV-2. Induced immunity (vaccination) is not a given either, some animal coronavirus vaccines protect against the disease while others exacerbate it, careful testing of vaccine candidates is very important. Chloroquine therapy is very promising, the earlier results need to be confirmed and several studies are in progress to do just that. Hydroxychloroquine is the most active form and the fact that it targets the host cell rather than a viral component is very important. It means that it will be much more difficult for the virus to mutate resistance to the therapy.


<h4″>In your opinion, will SARS-CoV-2 become seasonal, and could it re-appear/strengthen again upon releasing confinement measures?

I think it is quite likely this virus will become endemic throughout the world, with seasonal variation in its circulation. It is now propagating in the Southern hemisphere too, which is starting its “flu season” while ours is finishing, which will then finish when our next one is starting in the Northern hemisphere. It can certainly reappear when confinement is lifted and thus massive testing abilities are needed to be able to prevent a flare-up when we do. I don’t think the virus will show more pathogenicity when/if it reappears, the natural tendency for epidemic/pandemic viruses is to evolve towards less virulence as they become endemic in a population.


Studies have revealed the aerosol and surface stability of the SARS-CoV-2; however, we don’t know its viability on textile and fresh alimentation surfaces. According to the WHO, heat at 56 °C kills SARS-CoV-1: can we presume the same characteristic is true of SARS-CoV-2?

Yes, the physicochemical properties of SARS-CoV-1 and -2 are going to be very similar so I expect 56°C to fully inactivate SARS-CoV-2. The studies measuring life time of the virus on different surfaces have to be understood to represent very specific conditions in the laboratory, in particular if the virus is in solution by itself, as opposed to being embedded in mucus (as is often the case for nasal discharges or diarrhoea). The mucus protects against desiccation prolonging the viability of the virus. Consider what happened in Toronto in 2003 when SARS-CoV was no longer circulating in the community and there were no more cases in the hospital. The strict control measures were lifted and a full month later a new outbreak took place in one community hospital, presumably a fomite (any inanimate object that, when contaminated with or exposed to infectious agents can transfer disease to a new host) that was not cleaned reinitiated transmission, the virus having remained viable for a month.


What is your advice to the general public in terms of precautions and preventive measures, and what would you recommend to focus on when handling fresh alimentation, like bread, fruits or textiles?

The virus is quite fragile, wash fruits and vegetables with soapy water or detergent and rince well. Laundry with detergent, even only 30°C will take care of the virus on textiles. Bread is baked, which kills the virus, any baked food is safe unless subsequently contaminated of course. Two or three layers of a scarf in front of your mouth and nose will not protect you caring for a sick COVID-19 patient, but is better than nothing when shopping for groceries.

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