Clearly, with Covid cases on the rise, it is very important to determine what is driving this second wave. Are they students socializing in college? Or is it people who pack in bars?
It’s probably a bit of both, but there is growing evidence that the main driver is a small group called ‘superspreaders’.
They may not have any symptoms, but still manage to infect many others. In reality, relatively few people are responsible for most of the cases.
The researchers also showed that the people who produced the most droplets (the potential superspreaders) were usually older, with a higher BMI (body mass index). In other words, someone like Donald Trump. This group is not only more vulnerable to the virus, but also appears to be more susceptible to spread if infected
A striking example of a superspreader was 53-year-old Steve Walsh, who unknowingly managed to infect at least 11 others at the start of the British outbreak.
He got infected at a conference in Singapore and then went skiing. He infected most of the people in his chalet, but what was surprising is that they didn’t infect many others after that.
In fact, a nine-year-old boy in the lot who later tested positive for the virus did not pass it on to anyone else, despite coming into close contact with more than 170 people over the following days before being identified.
This is no fluke. It appears that 80 percent of new cases are caused by just 10 percent of infected people – most people who get Covid-19 never give it to anyone else.
A striking example of a superspreader was 53-year-old Steve Walsh, who unwittingly infected at least 11 others at the start of the British outbreak
If we can identify and quickly isolate the superspreaders, it could have a major impact on the spread of Covid.
So is there anything unusual about the people who become super spreaders? In a fascinating experiment, researchers at Harvard University in the US took 74 healthy volunteers and measured their breaths for two days, counting how many tiny droplets they exhaled.
They found seven individuals, or about 10 percent, who produced many more drops than the others.
The researchers also showed that the people who produced the most droplets (the potential superspreaders) were usually older, with a higher BMI (body mass index). In other words, someone like Donald Trump.
This group is not only more vulnerable to the virus, but also appears to be more susceptible to spread if infected. So, aside from the fact that they are probably older and heavier, how can you identify a superspreader?
At the moment the only way is with track and trace. This means a lot of testing and then tracking down contacts to see who caused the infection.
While researching my recent book on the coronavirus, I came across the story of the original superspreader, ‘Typhoid Mary’, which caused typhoid outbreaks in New York and other parts of the US in the early 1900s.
Typhus, caused by a salmonella infection, used to be a major cause of death in busy cities until sanitation improved.
During an outbreak in New York in 1907, the daughter of a wealthy industrialist died and he hired a researcher to find out why. This researcher found that a woman named Mary Mallon who had worked as a cook in their home had also worked in other homes where people had subsequently contracted typhoid fever.
Mary had no symptoms, but when doctors examined her poop, it was full 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 locked up in a hospital bungalow for three years and then released on the condition that she never worked as a cook again. But she just changed her name and continued to work.
She was eventually caught, a few years later, cooking in a hospital where a typhoid outbreak led to 25 people becoming infected and two dying. Mary was arrested and imprisoned until her death 23 years later.
To our modern sensibility this is inhumane, but the main difference is clearly that isolating a Covid superspreader would take days, maybe weeks, not years – if track and trace can recognize them.
But rather than identifying individuals, the key may lie in reducing superspreader events. These are one-time meetings where many people become infected.
It could be a pub, like the one in Aberdeen, where 13 people tested positive; or a convivial gathering of right-wing American politicians, chaired by Donald Trump, that led to seven cases.
Central to the idea of superspreader events is a new understanding of the virus – just as important as the R value (the number of people that someone typically infects) is the ‘K value’.
This is the pattern in which the virus spreads. In infections such as the flu, the K value is one: it is evenly distributed, with each infected person usually passing it on to each other.
The K value for Covid is lower – about 0.1 – suggesting that a small number of people cause the most infections.
And where are you likely to meet these super spreaders?
Basically, in busy indoor spaces that are poorly ventilated, filled with noisy strangers around, spraying lots of viruses.
On that basis, planes, cinemas, restaurants and theaters are reasonably safe; while crowded pubs and bars, especially where many people are shouting and laughing, are best avoided.
This may help explain some of the thinking behind the recent introduction of new lockdowns.
Years ago, while visiting Iceland, I decided to try a local delicacy, fermented fish. But the smell was so strong that I found it almost impossible not to gag, let alone scoff. Icelanders enjoy such delicacies because it is part of their culture, like the French with their smelly cheeses. But a new study in the journal Current Biology suggests there is also a possible genetic explanation.
It seems that a surprisingly large number of people in Iceland have a mutated version of the gene that allows most of us to detect and avoid rotten fish – the mutation means they don’t mind the smell, but actually quite enjoy it, if you it describes as sugary or floral!
The best time for a cup of coffee? 9:30 am
The first thing I do when I get out of bed in the morning is my resistance exercises – five minutes of push-ups and squats. I find that if I don’t do them then, I don’t do them at all.
Then I stumble down for a cup of tea, followed by a morning walk, if I have time, and then a cup of coffee for breakfast. My wife Clare prefers to save her caffeine hit for later in the morning. So who is right?
Well, a new study from the University of Bath suggests that Clare is – it appears that drinking coffee before breakfast disrupts blood sugar in a way that it doesn’t if you drink coffee afterward.
Another reason you might want to delay your coffee is that we all experience a brief rise in the hormone cortisol around the time we wake up, which brings us to life.
Cortisol is a stress hormone, but it also signals the body to wake up. Levels usually reach around 8:30 a.m., so adding caffeine on top of that can actually undermine its effectiveness.
Better to wait until at least 9:30 a.m., when cortisol starts to drop, before giving yourself a caffeine hit.
I stumble down for a cup of tea, followed by a morning walk, if I have time, and a cup of coffee for breakfast. My wife Clare prefers to save her caffeine hit for later in the morning. So who is right? [File photo]