As a small number of people — the super-spreaders — cause most of the new cases, the epidemic can be controlled by focussing on reducing the chances for them to transmit the virus. But what makes a super-spreader? Becoming a super-spreader depends on being highly infectious, but people also become super-spreaders because of what they do. As we all learn more about coronavirus, we have learned that there are certain activities we should avoid if we want to avoid exposure to the virus.
These include spending long periods of time in close contact with other people, indoors in poorly ventilated areas, and being among other people who are singing or shouting.
These activities can easily become super-spreader events, if someone in the group has coronavirus. The challenge with coronavirus is that people who have it are infectious before they have symptoms of the disease, when they are still asymptomatic. People can therefore become a super-spreader before they even know they are unwell. This means that, when there are a lot of people in a community who have coronavirus, we all need to avoid the sorts of activities which could lead to super-spreading, not just those who feel unwell.
Why is this lockdown happening? For how long? What happens after lockdown? Dr Elizabeth Webb answers these questions. Dr Elizabeth Webb continues her discussions of R, looking at the ways to keep the number as low as possible.
Dr Elizabeth Webb discusses the other symptoms of coronavirus being identified, and what it means to be 'asymptomatic'. Dr Elizabeth Webb discusses the difficulties of predicting how coronavirus will progress in future.
There are a number of theories, but no definite answer. Some speculate that it is to do with the immune system of the super-spreader, which may not be good at suppressing the virus or alternatively may be so good that they do not feel symptoms themselves so carry on transmitting it to others. But it is likely to be caused by multiple factors, possibly including getting a higher dose of the virus in the first place or being infected with more than one pathogen.
One thing seems certain — it is impossible to know who will be a super-spreader and who will not. It seems so. The third British case was a man in his 50s who contracted the coronavirus infection at a conference in Singapore. He then travelled to France where he stayed with his family in a ski chalet in the Alpine resort of Les Contamines-Montjoie. Five people who were in the chalet, including a boy of nine, have tested positive for coronavirus since the man came back to the UK on an easyJet flight and was diagnosed in Brighton.
Worryingly, this new strain is on the increase. From this data, they calculated that as after the November lockdown in England, although numbers of cases of the original COVID virus declined, there was an increase in the numbers of cases of the new variant.
Very recently, evidence has become available suggesting this new strain may have higher mortality. If super-spreaders, super-spread the new variant, this will be highly detrimental to controlling the pandemic. Higher rates of COVID infection were demonstrated in association with areas of increased population density.
These findings confirm the advice to stay at home — avoid crowds and crowded areas. They also show that COVID infection is likely to be easier to control in the warmer summer months, than in the winter. Much research has been undertaken, examining the details of viral transmission. The COVID virus is passed in droplets of respiratory mucous and saliva emanating from the mouth and nose. Saliva and mucous vary in consistency — they can be watery and thin, or thick and viscous.
On coughing or sneezing, thin, watery secretions are likely to travel further. Genetic differences affecting the quality and quantity of saliva and mucous may help or hinder the transmission of infection. Individual genetic variations may make viral infection or transmission more likely by other means. A Swiss study calculated that the cough of a super-spreader fills a room quickly with an incredible 7. Breathing heavily, shouting, or singing will increase the viral load further. This was the finding of a large meta-analysis published in The Lancet June which reviewed observational and 44 comparative studies on the use of face masks in preventing the spread of infection.
Failing to wear a mask has been linked to anti-social personality traits such as callousness, deceitfulness, hostility, manipulativeness and risk-taking, and a diagnosis of Antisocial Personality Disorder ASPD.
The super-spreader, on one hand, is an innocent perpetrator as for the most part, they are unaware they are infected and are transmitting infection. However, now we know super-spreaders exist, ignorance is not an excuse. Who are the super-spreaders?
The characteristics of the super-spreader are set out in Box 1. Any one of us could be a super-spreader, a very hard fact to bear on our conscience. Control of the pandemic depends largely on not allowing ourselves to become super-spreaders, as well as protecting ourselves from the invisible super-spreaders, already at large in the community. Save my name, email, and website in this browser for the next time I comment.
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