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On average, a Sars-CoV2 positive person infects 2.5 individuals (R0) if containment measures are not taken (masks, hand washing, social distancing).
However, sometimes an infected person transmits the virus to many more people and becomes a superpreader, that is, it transmits the virus to many more people than the average person. Biology plays a role to some extent in determining the role of these super-diffusing subjects.
High viral load (particularly high in the two days before symptoms start) can certainly play a role, but especially circumstances such as events in closed and crowded spaces, and activities carried out, matter, such as singing or intense physical activity where there is a greater spread of potentially infected droplets.
Therefore, they are more dangerous than anything else. overlapping events, or supercontagion events. Although any infected person can transmit the virus, there are circumstances in which infections can become uncontrollable.
Preventing these situations (avoiding them) or, in any case, wearing a mask can contribute decisively to stopping the spread of Covid-19.
The last recorded event occurred, by admission of the professor Anthony Fauci, in the White House, when Donald trump – then positive result – announced the election of Justice Amy Coney Barrett to the Supreme Court. The graphs you see below were made on the basis of a database compiled by professors and PhD students at the London School of Hygiene & Tropical Medicine.
The biggest blockbuster event in the world, in Milan
Super-pollution events around the world have created outbreaks of coronavirus infection that have spread like wildfire, often making full tracking nearly impossible. The largest outbreaks typically occur in hospitals or nursing homes and the chronicles have told stories from all over the world. But also religious ceremonies like weddings and funerals, business meetings, restaurants, gyms, farms, slaughterhouse, call center, parties, universities, prisons were Overlay events on tutto balloon.
Almost all contacts took place indoors where the lack of significant air exchange, the proximity of people (often without a mask), and prolonged contact facilitated the spread of the virus.
but still the largest known superpropagation event took place in the open air. This is the Champions League match on February 19 when Atalanta hosted Valencia at the San Siro stadium in Milan. The event was called game zero because the match took place just two days before the confirmation in Italy (and outside of China) of the first positive case of Covid-19. That game was defined by the Chief of Pulmonology at the Papa Giovanni XXIII hospital in Bergamo by a biological pump. No one knew that the virus had crossed the borders of China. It is very likely that 40,000 people from Bergamo in the San Siro stands, in total, infected each other. And those who gathered at home or at the bar to watch the game did the same. 2,500 Valencia fans were also present at the stadium: a few weeks later 35% of the Spanish team tested positive for the new coronavirus. 7,000 infections were related to that game.
The first cases of overcast
The Milan stadium is an exception. At that time, nothing was known about the coronavirus and what happened was inevitable. Since then, similar events have taken place around the world, but on a smaller scale and mostly indoors. In February, a 61-year-old South Korean woman who attended a place of worship was held responsible for the infection of about fifty people present at the event. In the United States, an asymptomatic showgirl infected 53 of his colleagues during singing rehearsals in Washington state and two people died. Later, other infections occurred among members of other choirs (singing was considered a risky activity). At the end of February, the annual meeting of the pharmaceutical company Biogen in Boston was one of the first cases of Covid-19 super-spread in the United States: after the meeting between 175 executives, the participants boarded several planes and took the virus to six states. different from the US and three foreign countries.
Indoor sports
Indoor sports are considered especially dangerous places because if an infected athlete, under physical effort, exhales with more intensity and emits a greater amount of potentially infected particles. In the same way, the others present who carry out sports activities breathe more vigorously, with the risk of introducing high levels of virus into their body. In a curling competition, a typically Canadian sport, a super diffuser infected 72 participants. Curling involves close contact between players and teams that play in a cool, indoor, and breathable environment for an extended period of time. The tournament ended with 24 infected out of 72 in attendance. A high-intensity Zumba lesson in South Korea in confined spaces sparked a string of infections: As of March 9, researchers had tracked 112 cases of Covid-19 linked to those. dance lessons in twelve different gyms in Cheonan city.
Work environments
Research has repeatedly found that the risk of transmission of the coronavirus increases indoors in poorly ventilated spaces where many people have prolonged contact. The open spaces of the offices, where employees are in contact for many hours, can represent a serious contagion problem if the mask is not worn correctly, as happened in a call center in South Korea where only one positive infected 94 colleagues . Among the opportunities for over-diffusion are also meat producing and packaging companies: in these plants, workers work in close contact with each other and are forced to dialogue in a very noisy environment due to the machinery in operation, and low temperatures (which facilitate virus survival). In the United States there are hundreds of food industries involved in the outbreaks with thousands of positive cases and dozens of deaths. In Germany, large outbreaks in slaughterhouses have infected more than 2,000 people. Italy also recorded outbreaks in Mantua sausage factories with a final count of about 70 cases. For the same reason, the close contact between workers is also the plant in Aia di Vazzola, in Veneto, which has become a place of super spread with 184 infections.
How to avoid overlapping events
Some countries like Japan or South Korea have already shown that it is possible to deal with an outbreak without drastically limiting the movement of citizens or closing all shops, schools and restaurants thanks to compliance with the 3C rule. In fact, governments have invited people to avoid: closed spaces, crowded places, close contact environments or closed spaces, crowded places and close contact contexts, which are ideal for high-profile events. The last known event, undoubtedly one of the most famous, was the ceremony on September 26 when Donald Trump appointed Amy Coney Barrett as Supreme Court Justice in the Rose Garden (outdoors). On that occasion the rules of distancing were not respected and almost none of the guests wore a mask. As for the San Siro stadium, despite the open space, the virus traveled thanks to the proximity of the guests. Thus, the virus would have entered the White House, infecting the president among many.
October 10, 2020 (change October 10, 2020 | 10:08 am)
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