Special K

"Superspreaders" is a name given to individuals infected with the novel coronavirus who pass it on to a very large number of their contacts. Many examples have been reported. For instance 29-year-old man infected 101 people after visiting several nightclubs in Seoul, South Korea; a singer unwittingly infected 52 fellow singers at a choir practice in Mount Vernon in Washington State in early March. Most of these multiple transmissions have taken place in crowded, poorly-ventilated places where the spreader was expelling plenty of virus-laden breath, say by singing or talking loudly over background noise. 

We have heard much about the statistical parameter R, called the epidemic reproduction number; it is the average number of contacts an infected person will pass the virus on to. For the coronavirus SARS-Cov-2 in a fully-susceptible population, the value of R lies between 2 and 3 in urban settings. As a proportion of the population becomes immune and social restrictions reduce the number of contacts, the value of R declines, and when it falls below 1, the epidemic will start to retreat. There is another parameter epidemiologists use called K. The value of K represents the level of individual variation in R. When K is small (less than 1), there will be wide variation in the number of people one infected person will infect; in particular, there will be more so-called superspreaders. In the early stages of the outbreak of covid-19 the value of K was between 0.1 and 0.5 which meant that 10-20% of those infected probably generated about 80% of the transmissions. An increase in the value of K, to above 5 say, will reflect the fact that the number of transmissions generated by most individuals will be close to the value of R.

Imagine a group of 200 individuals in a large population and divide them into  say 50 who are shielded and at no risk, and the other 150 who are moving out of lockdown as now. Assume that the number of active infections has significantly fallen and that the reproduction number is just below 1. Just as it was at the initial outbreak, the value of K will be small and the risk of the return of superspreaders high; it will only need one or two of them among the 150 to send the R-number soaring. This is why an effective test-and-trace system is so important at this stage, to catch the potential superspreaders before they have a chance to set off a second wave.

Production of Mighty Marmite marred

An unlikely casualty of the pandemic is the supply of that famous metaphor love-it-or-hate-it Marmite, which now only available in small jars, A key ingredient is dead yeast cells, which are a healthy by-product from brewing beer, and with pints no longer being pulled in the pubs, the supply has dwindled.

Up close and dangerous

One metre or two? That is a question exercising politicians right now. Halving the current social distancing guideline of two metres would make a huge difference to the viability of the hospitality industry, which has taken a big hit during the lockdown.

Two metres is already not safe. The risk depends on many contingencies. Let’s assume your face is two metres from the face of someone already infected with the virus. Whether you catch it will depend on:

• How long you spend with them
• How infectious they are
• How many water droplets and aerosols they are expelling; in particular whether they cough or sneeze in your direction
• Whether you are facing each other and which way the air currents are moving
• Whether one or both of you are wearing masks

The transmission risk will be proportional to the time you are exposed. Evidence suggests there is a wide variation in individual infectiousness. It is higher if your contact is breathing heavily, speaking loudly or singing. It depends on what stage of infection they are at and how heavy their ‘viral load’ is. It will be much worse if you are in a crowded space with poor ventilation, such as a pub or night-club.

A recent meta-study - a study of studies - suggests that using one metre instead of two for your social distancing will double the risk of contagion, but that’s just an average and the confidence margins are wide. The real risk depends on the detailed circumstances of your encounter and these override the simplistic calculations derived from the meta-study.

Two More Free National Theatre Productions on YouTube

The Deep Blue Sea

Terence Rattigan’s devastating masterpiece contains one of the greatest female roles in contemporary drama, played by Helen McCrory.

Streaming from 7pm on 9 July, until 7pm on 16 July.

Find out more

Amadeus

Lucian Msamati plays Salieri in Peter Shaffer’s iconic play, directed by Michael Longhurst with live orchestral accompaniment by Southbank Sinfonia.

Streaming from 7pm Thursday 16 July until 23 July.

Find out more

Covid Analysis Apps

The Covid Symptom Tracker described below now has nearly 4 million contributors. Scientists at King's College London are using it to identify (i) high-risk areas in the UK, (ii) who is most at risk, by better understanding symptoms linked to underlying health conditions and (iii) how fast the virus is spreading in your area. The more people who join, the more useful the data. Your daily report takes only 15 seconds - tap, tap, tap! Please sign up if you have not already done so.

Another app that is gathering covid-related research data has longer term goals. It is called Covidence UK and is led by Queen Mary London in a consortium of 6 Higher Education Institutions from England, Scotland and Northern Ireland.

                          

People aged 16 years or older, from all parts of the UK and from all walks of life, are invited to sign up and fill in an online questionnaire with details about their lifestyle and health.

Participants will then be contacted every month to check if they have developed any symptoms of coronavirus disease, and to ask some follow-up questions about participants' more general health and social circumstances.

The data they collect will be analysed in order to:

• advance understanding of risk factors for coronavirus disease among UK adults
• find out how quickly people recover from coronavirus disease and whether there are any long-term complications of this illness
• evaluate the impact of coronavirus disease on the physical, mental and economic wellbeing of the UK population
• establish a platform for future research on coronavirus disease in the UK.

Curly Sceptic (anag, 7,5)

1. A reminder that ‘social distancing’ needs to be policed

            Deal with some backsliding males in a group (8)

by first-prize winner, Jane Ainsworth, in The Telegraph monthly clueing competition.

2. Another reminder, this time of the change of leadership in the British Labour party:

            Bad mistake, error ousting old Labour leader (4,7)

from a Paul Bringloe crossword in The Telegraph.

3. And finally this double definition, which has nothing to do with the cladding on New England houses:

Old boarding (7.2)

A ‘double definition’ means that the solution is synonymous with both ‘old’ and ‘boarding’.

Safe Bet

Take three dice A, B and C and change the numbers on two faces of each as follows:

A: 1, 1, 3, 5, 5, 6       B: 2, 3, 3, 4, 4, 5      C: 1, 2, 2, 4, 6, 6

Find someone who enjoys a wager, ask them to choose a die. Then choose your die to be the one to the right of theirs in the sequence ABCA. Bet them a pound that if you both roll different numbers, your roll will higher than theirs. After 100 rolls you can expect to be around six pounds up on average! (For more information see the Wikipedia article Nontransitive Dice.)

Update: Since posting the above, I have written a short program to simulate the game. The average profit over a 1000 games of 100 rolls each was £6.76 per game, reasonably close to the theoretical figure of £6.25. Averaged over 100,000 games the simulation's predicted profit per game was even closer at six pounds and 24.84 pence. But be warned, there were significant deviations from the mean, with the 100-roll games occasionally showing a negative profit!

Jude the Obscure

This is the title of the last of Thomas Hardy’s twelve or so published novels, depending how you count them. He also published many short stories and volumes of verse, and regarded himself principally as a poet. Among the major themes in his writing is a sense of loss for the old traditions and the devaluation of the rural ways of life as many moved from the countryside to the towns and cities. In Jude the Obscure, Hardy offers a biting critique of the rigidity of the law and social attitudes on marriage and the obstacles to social mobility due to poor education and snobbery. Jude went to a village primary school and learnt to read and write (as did I), but after that he was on his own. He was ambitious, nevertheless, and knew that a key to bettering himself was a knowledge of the Classics (see previous post), an insurmountable hurdle devised by the higher social classes to ensure their offspring didn’t end up working down a mine. Jude had his sights on Oxford (called “Christminster” in the novel) and was able to purchase cheap or second-hand editions of the books he needed, from Latin primers to Anglican tracts. He kept these books by his bedside and dreamt of joining the “great thinkers” while burning the midnight oil in private study even after a long day’s labour as a stonemason. But when he arrived in Oxford, his only way into the colleges was to repair their crumbling masonry. When Jude writes a letter to five heads of college, only one bothers to reply, and his curt advice that Jude should be content to stick to his trade.

I read the novel only recently for a book group and confess that I was disappointed in it. Having admired Hardy over the years and having been prepared to put up with the pessimistic endings to many of his stories, I felt this one verged on the melodramatic and that Jude’s decline into obscurity offered too bleak a vision of the future. In personal terms I have been better treated in life than Jude. I got a decent education, including some Latin, despite the bookless social class I was born into. Moreover, no-fault divorce became British law earlier this year. Hardy might be smiling quietly to himself in his tomb in Westminster Abbey that his hope for a fairer world has come to pass. Jude got some vicious critical reviews and Hardy never wrote another novel. In a postscript to the original preface, written 16 years later, he indicated that he had been creatively wounded by the hostility of the response to what one critic called "the most indecent book ever written". But I have a suspicion that perhaps Hardy felt he had written himself out and was secretly happy to call it a day.

Classical, Classics and Class

The word “class” has an interesting etymology, as I learnt recently from Edith Hall in an episode of Start the Week on BBC Radio 4 (on 25th May). The Latin word “classicum” meant, among other things, a war-trumpet or a military trumpet call - the word also had nautical associations - and it was used, so legend has it, by Servius Tullius. the sixth king of Rome, to announce roll-calls of Roman citizens in their separate groups according to their social status and wealth for voting and taxation purposes. So the word “class” became associated with Rome’s six taxation ‘classes’, especially with the highest class. Modern usage the word can mean a teaching group (as in ‘‘ top of the class’), a social stratum (as in ‘working class’), or a quality of distinction (as in ‘class act’); ‘class’ also has technical meanings in taxonomy and mathematics. While ‘classification’ retains just the division-into-categories meaning, the words ‘classical’ and ‘classic’ have overtones of something of quality with a gilded past, although when applied to music, ‘classical’ has a narrower meaning. Finally, the word “Classics’ has come to mean the study of the languages, literature and history of ancient Rome and Greece as well the wider culture of their associated civilizations, which flourished during the last six centuries BCE and beyond. In more recent British history the acquisition of a ‘classical education’, typically involving 8 years of swotting up Greek and Latin, was the unique passport to wealth and the power, and separated the ruling class from the hoi polloi. But more about that in my next post.