Professor Alberto Mantovani, Scientific Director of Humanitas and Professor Emeritus of Humanitas University, recently clarified some points about the COVID-19 pandemic by intervening in some radio and television broadcasts.
Do we know more about the new Coronavirus SARS-CoV-2?
“We know more about this virus and we have made progress even if it is not as fast as we would like; we understand its epidemiology better and how it spreads, we also know its structure better and this has allowed us to identify molecular targets for possible vaccines. We are trying to verify if and how the virus activates a friendly fire, that is an immune response that paradoxically creates damage to the body; nevertheless SARS-CoV-2 continues to remain an enemy that we do not know from a scientific point of view and as a community.
What are the open questions?
“We know that older people are more susceptible, probably because the immune system ages over time and therefore is less responsive to pathogens; and certainly because the possible presence of other chronic diseases do not help. We also know that women are more resistant to COVID-19 and it is possible that this depends on the fact that in some contexts they have more effective immune responses. Another element to consider is that women smoke less than men (or rather smoked less) and therefore it is possible that their lungs are less damaged by previous smoking. We also know that children rarely get sick: some scientists – including myself – think that this may be related to the fact that the vaccinations that children undergo train their first lines of defence and give protection not only against the specific germ for which they are designed (such as those against measles and tuberculosis). Our immune system, in fact, has the first line of defence (the so-called innate immunity) that manages more than 90% of the encounters with pathogens, but we do not know if this works against SARS-CoV-2 and if we can train its members.
These are some of the questions we ask ourselves in front of the patient’s bed and it is essential to do research to answer them”.
Are there mutations in the virus?
“There is a discussion in the scientific community as to whether the mutations identified so far change its pathogenicity, this is another question we need to answer.
When will we have a vaccine available?
“At the moment there are about twenty strategies in the field to develop a vaccine and this is very important because the virus is unknown to us and therefore we do not know the protective immune responses well. The first phase (i.e. the identification of molecular targets) is relatively rapid, but then the development phase (testing safety and efficacy with rigour) takes more time. I think it will take 18 months to get a vaccine against SARS-CoV-2”.
What is herd immunity and how is it built?
“I prefer to talk about community immunity, where the concept of solidarity and attention to the most fragile is inherent. It is a mechanism that is established in a community so that if the majority of individuals are vaccinated, the circulation of an infectious agent is limited, thus protecting even those who cannot undergo vaccination, perhaps because of particular health problems. It is a fundamental mechanism to reduce the transmission and circulation of infectious diseases.
Community immunity is built in two ways: either with a vaccine or spontaneously, as is the case with influenza, for example. When the annual influenza epidemic arrives, most people have already been exposed to the influenza virus in previous years (the virus may be the same as the year before or a relative) and therefore have some immune response capacity. Not only that, but a share of the population (albeit low, unfortunately) has also been vaccinated against influenza, so this immunity situation in the community cushions the impact of influenza”.
How long does it take to reach spontaneous herd immunity?
“It depends on how much you leave the virus free to run, but if we did this with SARS-CoV-2 for the health system – and we see it in Lombardy – the situation would be unsustainable and it’s a luxury we can’t afford, it’s once again important to reiterate how fundamental it is to stay at home. Moreover, we are not sure that the antibodies are protective against the new coronavirus, although it is reasonable to think so, just as we are not sure how much immunological memory the virus leaves and how long it lasts.
Immunological memory is fundamental for herd immunity for most infectious diseases, in fact, we do not look for the germ, but a trace of the germ living in our immune system. Let’s take rubella for example, which, thanks to the vaccine, is no longer a big problem. Before the vaccine, antibodies were searched for in pregnant women through a blood test. The class looked at the results to see if the exposure to the virus was recent or a trace of the past and therefore in this case it was irrelevant for her pregnancy.
Antibodies are a fundamental tool and will really allow us to evaluate the epidemiology of this disease in the future, but research work on this front is also fundamental”.
Does lifestyle influence the immune system?
“In general, lifestyle has great importance in keeping the immune system in shape. For me, this means not smoking, consuming fruit and vegetables (because some of the components they contain activate some of our cells that are the first line of defence, although we still don’t know how this happens), taking moderate exercise (30 minutes a day), and keeping our weight under control. In cases of overweight people, the cells of the immune system present in the adipose tissue are disorientated and produce inflammatory mediators that probably represent a friendly fire that contributes to the damage.” Prof. G. M. Mantovani concluded.
This article is taken from the interviews given by Professor Alberto Mantovani to Radio Anch’io, Radio Rai 3 Scienza, and Tg Leonardo.