C.hina now wants to explain the pandemic to the world, and this also applies to the corona mask question, which not only German experts (and therefore politicians) obviously have a hard time with. At any rate, virologists have carried out experiments at the University of Hong Kong, and not even very complex ones, to prove the effectiveness of respiratory masks in the coronavirus pandemic. Conclusion of the study: “We have shown that surgical masks effectively reduce the detection of coronaviruses in droplets and aerosols.” This is the result of a short correspondence published in the internationally renowned scientific journal “Nature”.
The conclusion in this summary form largely coincides with the latest assessment by the German National Academy Leopoldina. However, the German group of experts continues to lean out of the window: Because the masks reduce the ejection of droplets by infectious people, according to the Leopoldina experts, “mouth-nose protection protects other people, thereby reducing the spread of the infection and reducing it thus indirectly the risk “. Healthy, not yet infected people are protected. There is not much scientific evidence for this special, very plausible assumption, but it remains according to the latest Chinese “Nature” publication.
The Hong Kong researchers have experimented extensively with and without a mouthguard, but they also worked under very controlled experimental conditions, as is customary in experimental research. It starts with the surgical masks used: commercially available face masks for hospital staff, international standards, but just that. What applies to these masks made with standardized mesh sizes and materials cannot simply be applied to converted neckerchiefs or T-shirts, vacuum cleaner bags or Do-it-yourself variations of brightly colored silk scarves are transmitted to the mouth and nose.
So if the Hong Kong researchers in their experiments with 111 infectious patients show that the virus output is reduced by a professional mouthguard for the infected, this is not a free pass for provisional masks. It is worth taking a closer look. This also applies to the experiments themselves: for understandable reasons, there were no Sars-CoV-2 infected among the infected test participants.
Rather, people have been identified who suffer from the consequences of other well-known cold viruses: influenza and rhinoviruses as well as endemic coronaviruses that have been circulating in the world for decades. They are similar to the new corona virus, the causative agent of Covid 19 disease, in two crucial respects: They are also RNA viruses and are widely distributed when sneezing, coughing and when talking with droplets when wet.
The study was therefore designed in such a way that far-reaching conclusions can also be derived for other epidemic agents. The patients were placed with and without a mask for thirty minutes in front of a detector (“Health II”), which records the ejected droplets and the much finer aerosols (less than five micrometers), registers them and collects them for the subsequent virus analysis. An experimental setup that should come as close as possible to real conditions. This also applies to breathing behavior and symptoms. Those who could not cough or sneeze from the infected during this time did not have to force it.
And in this regard, one sentence strikes at the end that almost forces further examinations: Virus transmissions were also registered in those infected, albeit in considerably fewer numbers who remained asymptomatic – neither sneezed nor coughed. In other words, the droplets occasionally expelled while breathing and also the much more airy tiny aerosols sometimes contained virus material. How infectious these virus particles are cannot be said. One thing is clear: with the corona viruses examined, the risk of transmission when breathing is much lower than with influenza and rhinoviruses. How the amount of viruses emitted apparently varies greatly from person to person. In half an hour of the experiment, thirty percent of Hong Kong’s subjects emitted droplets loaded with corona viruses, and forty percent aerosols loaded with viruses. In such tiny, invisible aerosols, however, the corona viruses, which are already considered to be rather unstable and sensitive to dehydration, are unlikely to survive long.
And there is something else that gives hope in relation to the Covid 19 pandemic: The surgical masks have filtered the coronaviruses out of the air stream from the throat of the infected much more efficiently than with the other viruses. When the corona patients put on the mouthguard, virus material was not detectable either in the droplets or in the aerosols. All in all, this suggests that professional respiratory protection offers real protection, especially for corona viruses. In the words of the Chinese researchers: “This has important implications for the control of Covid-19, and that means that surgical masks could be used to reduce the transmission of viruses by sick people.”