SUPERSPREADER

Clue: They look like Trump

could have a big impact on the spread of Covid.

So is there something unusual about the people who become superspreaders? in a fascinating experiment, researchers from harvard University in the U.S. took 74 healthy volunteers and measured their breath over two days, counting how many tiny droplets they breathe out. they found seven individuals, ie roughly 10 per cent, who produced far more droplets than the others.

the researchers also showed the people who produced the most droplets (i.e. the potential superspreaders) tended to be older, with a higher BMI (body mass index). in other words, someone like Donald trump.

this group are not only more vulnerable to the virus, but it seems more prone to spread it if infected. So, beyond the fact that they’re likely to be older and heavier, how can you identify a superspreader?

At the moment the only way is with track and trace. this means doing lots of testing and then tracking back contacts to see who’s been doing the infecting.

While researching my recent book on the coronavirus, i came across the story of the original superspreader, ‘typhoid Mary’, who seeded outbreaks of typhoid fever in New York and other parts of the U.S. in the early 1900s.

typhoid, which is caused by a salmonella infection, used to be a major killer in crowded cities until sanitation improved.

During an outbreak in New York in 1907, the daughter of a rich industrialist died and he hired a researcher to find out why. this researcher discovered that a woman called Mary Mallon who’d worked as a cook in their house had also worked in other houses where people had subsequently got typhoid.

Although Mary had no symptoms, when doctors examined her poo it had lot of salmonella bacteria. Mary was a carrier, and in a time before antibiotics, there was nothing to cure her.

to protect the public she was confined to a hospital bungalow for three years and then released on condition she never worked as — around 0.1 — suggesting a small number of people cause most infections.

And where are you likely to meet these superspreaders?

Essentially, in crowded indoor spaces that are badly ventilated, filled with noisy stranger sin close proximity, spraying lots of viruses around.

On that basis, planes, cinemas, restaurants and theatres are pretty safe; while busy pubs and bars, particularly where there are lots of people shouting and laughing, are best avoided.

this may help explain some of the thinking behind the recent introduction of new lockdowns.