Herd Immunity – what’s in a name?

Posted on 29th March 202029th March 2020 by Edward Wawrzynczak | Leave a comment

“Herd immunity” recently made a controversial appearance in the context of the current COVID-19 pandemic. What does the phrase mean, where did it come from, and how helpful is it today?

As of March 2020, the OED defines it as, “resistance to the spread of a contagious disease within a population that results if a sufficiently high proportion of individuals are immune to the disease, typically as a result of having been vaccinated against it”.

The earliest use of the phrase can be traced to a 1917 report from the US Bureau of Animal Industry that dealt with a cattle infection causing death of unborn calves. A cow that had aborted was likely to become immune, and calves born and raised in such an affected herd were tolerant to the disease. The authors concluded that “a herd immunity seems to have developed as the result of both keeping the aborting cows and raising the calves”.

However, the senior author, Dr Adolph Eichhorn, Chief of the Pathological Division, made no reference to herd immunity in a monograph to which he contributed a major section on biological therapeutics just two years later. His biologically apt coinage does seem to have been picked up in US agricultural circles, but it was not universally adopted, with “immunity of the herd” being used instead.

The concept of herd immunity next appeared in British bacteriologist William Topley’s epidemiological studies of bacterial infection, which examined the resistance of a population of mice after immunising animals with suspensions of bacteria. He used “herd-resistance” to describe the natural resistance of individuals within a population. And he discussed the implications of his work with the “mouse herd” for the “human herd”.

The human herd entered this experimental realm at about the same time. In 1922, Surgeon-Commander Sheldon Dudley studied a diphtheria epidemic at Greenwich Hospital School. He found that the longer boys had been resident the greater the proportion who were immune, and that increases in immunity correlated with each outbreak. He extended such studies to other infectious diseases and used herd immunity to explain his findings.

In 1928, all boys in the school were actively immunised against diphtheria. The most senior became immune (Schick-test negative) twice as quickly as the most junior, suggesting prior exposure to the disease (see Figure). These results paralleled earlier work in animals, except for the fact that “a herd of human boys were used in lieu of the guinea-pigs”.

Dudley was unapologetic for using the prefix herd to denote the properties of a community, pointing out that psychologists had earlier popularized the phrase “herd instinct”. Besides, on evolutionary grounds, there was “little fundamental difference between a herd of deer, a herd of swine, and a herd of Homo sapiens”.

Notions of herd immunity have become more sophisticated in recent decades owing to the increased importance of vaccination. Today’s NHS website defines the benefits thus: “If enough people are vaccinated, it’s harder for the disease to spread to those people who cannot have vaccines. For example, people who are ill or have a weakened immune system”.

The reader is also directed to more information and an animation on the website of the Oxford Vaccine Group’s Vaccine Knowledge Project . This site suggests that a better name for herd immunity is “herd protection” because it helps to protect those especially vulnerable to infectious diseases. “Community immunity” appears as an alternative.

Conveying the value of herd protection or community immunity to the public will be critical in successful vaccination against COVID-19. One must worry that the lazy use of a century-old phraseology rooted in the farm, mouse lab and human guinea-pigs, as well as a contemporary profusion of alternative terms, may prove more of a hindrance than a help.

Words by Edward Wawrzynczak

Sources used:

Horton, R. (2020) Offline: COVID-19 – a reckoning. Lancet, 395, 935.
https://public.oed.com/updates/new-words-list-march-2020/.
Eichhorn, A. & Potter, G.M. Contagious Abortion of Cattle. In: Farmer’s Bulletin 790, Washington DC: United States Department of Agriculture, 1917.
Winslow, K. & Eichhorn, A. Veterinary Materia Medica and Therapeutics, Eighth Edition. Chicago: American Veterinary Publishing Co, 1919, pp.525-563.
Beechy, L.P. (1920) Abortion disease in cattle. Bulletin of the Ohio State University Agricultural College Extension Service. Vol. XVI, No. 1.
Smith, T., Little Further studies on the etiological role of Vibrio fetus. J Exp Med, 32, 683-689, R.B. &Taylor, M.S. (1920).
Topley, W.W.C. & Wilson, G.S. (1923) The spread of bacterial infection. The problem of herd-immunity. J Hyg, 21, 243-9.
Topley, W.W.C. Wilson, J. & Lewis, E.R. (1925) Immunisation and selection as factors in herd-resistance. J Hyg, 23, 421-436.
Greenwood, M. & Topley, W.W.C. (1925) A further contribution to the experimental study of epidemiology. J Hyg, 24, 45-110.
Dudley, S.F. (1922) The relation of natural diphtheria antitoxin in the blood of man to previous infection with diphtheria bacilli. Brit J Exp Pathol, 3, 204-209.
Dudley, S.F. The Spread of Droplet Infection in Semi-isolated Communities. Medical Research Council, Special Report Series, No.111, London: HMSO, 1926.
Anon. (1927) The spread of infection in schools and ships. BMJ, 1(3443), 34, 1 Jan.
Dudley, S.F. (1928) Natural and artificial stimuli in the production of human diphtheria antitoxin. Brit J Exp Pathol, 9, 290-298.
Dudley, S.F. (1929) Herds and individuals. J R Army Med Corps, 53, 9-25.
Fine, P., Eames, K. & Heymann, D.L. (2011) “Herd immunity”: a rough guide. Clin Infect Dis, 52, 911-916.
https://www.nhs.uk/conditions/vaccinations/why-vaccination-is-safe-and-important/.
https://vk.ovg.ox.ac.uk/vk/herd-immunity.
Betsch, C. et al. (2017) On the benefits of explaining herd immunity in vaccine advocacy. Nat Hum Behav, 1, 0056.
Hakim, H. et al. (2019) Interventions to help people understand community immunity: a systematic review. Vaccine, 37, 235-247.

Laughter is the best medicine

Posted on 9th February 20209th February 2020 by Edward Wawrzynczak | Leave a comment

Anyone who has read doctor-turned-comedian Adam Kay’s best-selling ‘This Is Going to Hurt’ about his experiences on the obstetrics wards will be aware that medicine provides rich pickings for humour and satire.

But Kay is not the first person to draw on medical experiences to amuse his audiences. For as long as modern medicine has existed, medics and patients have been finding the humour in their experiences, helping to inform on attitudes and experiences from that time.

One such example is this excerpt from the October 1869 magazine, Punch. Written by Francis Cowley Burnand, a nineteenth century comic writer and playwright whose popular column ‘Happy Thoughts’ describes the difficulties and distractions of everyday life.

: Image courtesy of Peter Burke

: Image courtesy of Wellcome Library

: Image Courtesy of Wellcome Library

In this excerpt, Burnand turns his attentions to the doctor’s waiting room, in a scenario that will be very familiar to anyone who has ever made an appointment to see their General Practitioner. The narrator’s attempts to catch the doctor’s eye and jump to the front of the queue are ultimately dashed and he is forced to wait his turn like everyone else. The incident ends in embarrassment when he misplaces the doctor’s fee inside the lining of his coat.

The gentle observational humour illustrated in this column gives insight into the type of medical treatment available to the upper classes, while also demonstrating how little doctor’s waiting rooms have changed in the last 150 years.

The working relationship between doctors and nurses is also very neatly satirised in the following engraving from 1891. The Doctor asks the Nurse: “How is the patient this morning?” To which she replies, “Well – he has been wandering a good deal in his mind. Early this morning I heard him say ‘What an old woman that doctor is!’ – and I think that was about the last really rational remark he made.”‘

This comedic interchange about a delirious patient could just have easily occurred on one of today’s NHS medical wards.

As well as providing entertainment, humour and satire have also been used to highlight public health and social issues. In the following satirical cartoon from an 1893 issue off Punch, ‘Mr Punch’ remonstrates with a policeman about a quack doctor selling his ‘remedies’ on the streets of London. Saying, ‘And if Punch’s ready bâton lays its thwacks on any back with special zest, it is on charlatans and quacks.’

The cartoon highlights the movement against quackery towards the end of the nineteenth century, with a higher degree of ‘outcry’ against quacks that promoted false and unproven health claims for financial gain. While we are less likely to see ‘cure-alls’ pedalled on street corners, ‘quackery’ in the form of misinformation regarding vaccination and cancer treatments still exists as a scourge in modern medicine.

Flora Malein

The October 1869 Happy Thoughts article in full:

Image courtesy of Peter Burke

Sources used:

Chisholm, Hugh, ed. (1911). “Burnand, Sir Francis Cowley” . Encyclopædia Britannica. 4 (11th ed.). Cambridge University Press. p. 848.

The Wellcome Library

Tuberculosis, Philately and the history of the ‘Christmas seal’

Posted on 29th December 201931st December 2019 by Edward Wawrzynczak | Leave a comment

Paris: Comité National de Défense contre la Tuberculose; Quimper: Comité d’Hygiène Sociale du Finistère, [between 1930 and 1939?]. Image Credit: Wellcome Collection, CC BY.

Christmas has long been recognised as a time of charity and fundraising. Perhaps familiar to some is the ‘Christmas seal’ – a label placed on post over the Christmas period – to raise awareness and funds for charitable organisations.

Christmas seals fall into a category known as ‘cinderella stamps’: items that resemble stamps but cannot be used in payment for postage

While the Christmas seal concept has been adopted to raise funds for many different types of charitable organisations, they have most closely been allied to raising awareness of tuberculosis. According to a New York Times article, the concept originated in Denmark in 1904, when a Danish postal worker called Einar Holbøll came up with the idea to sell the penny seals to raise money for children with tuberculosis.

Other countries quickly followed suit with fundraising seals being produced to support tuberculosis causes in Sweden, Iceland and Argentina.

At the time, tuberculosis was still one of the major causes of death globally. And despite the discovery of the M. tuberculosis bacillus by Robert Koch in 1882, no effective treatment had been found. Organised national efforts to combat the disease were looking for means to raise awareness and financial support for the disease. These campaigns can be seen as some of the very first public health initiatives, in which the financial contributions of ordinary people were used to fund treatment of a disease.

Picture credit: W. Dibb Private Collection.

The first American Christmas seals were produced in 1907 by a Red Cross volunteer called Emily Bissell, who adopted the idea to help raise money for a tuberculosis sanatorium in Delaware that was under the threat of closure if a sum of $300 was not raised.

Although she could not get permission to have the U.S. national postal service to print and distribute the seals, as they had in Denmark, she was allowed to privately sell the seals in the post office lobbies. The seals were such a success they raised over ten times the amount needed and became an annual tradition that raised major funds for The National Tuberculosis Association (now known as the ‘American Lung Association’). The American Lung Association continues to sell their Christmas Seals™. Selling tuberculosis Christmas seals has also funded major disease prevention programmes in countries, such as Canada, through chest X-ray screening or tuberculin tests.

The Cross of Lorraine

National Tuberculosis Association, 1940. Image Credit: Wellcome Collection, CC BY.

Many examples of the Christmas seals created to raise funds for tuberculosis charities contain the symbol of the double-barred cross. Symbolically known as the ‘Cross of Lorraine’, it was adopted as the symbol of the fight against tuberculosis at the International Conference on tuberculosis held in Berlin, 1902.

A French doctor – Gilbert Sersiron – proposed the emblem which had been the banner of Godfrey of Bouillon, one of the leaders of the first Crusades who successfully laid siege to Jerusalem and became it first ruler. In adopting this Crusader symbol, the cross became a symbol of the new, organised anti-tuberculosis ‘crusade’.

Flora Malein

You can read more about postal items and infectious disease in a previous post, here.

Sources used:

The New York Times: https://www.nytimes.com/1989/12/24/style/pastimes-stamps.html

The American Lung Association: https://www.lung.org/get-involved/ways-to-give/christmas-seals/history.html

The Canadian Lung Association: https://web.archive.org/web/20111115234620/http://lung.ca/involved-impliquez/christmas-noel/history-histoire/index_e.php

TB Alert: https://web.archive.org/web/20090302074617/http://www.tbalert.org/about/cross.php

John, Simon (2017). Godfrey of Bouillon: Duke of Lower Lotharingia, Ruler of Latin Jerusalem, c.1060-1100. Taylor & Francis. ISBN 978-1-317-126300.

https://wellcomecollection.org/works/msbjucxs

https://wellcomecollection.org/works/hdh9a7xw

The Humble Toothbrush

Posted on 5th August 20195th August 2019 by Edward Wawrzynczak | Leave a comment

This blog focuses on the humble toothbrush: that everyday object that we too easily take for granted. Although many may consider the toothbrush a fairly insignificant and disposable item, it actually has rather an interesting history…

Early forms of the toothbrush have been in existence since about 3000 BC. Some Egyptian tombs have been found to contain ‘toothsticks’ demonstrating that cleaning teeth was clearly considered an important activity thousands of years ago.

It wasn’t until 700 AD that bristle toothbrushes were invented in China. These toothbrushes comprised of handles made of bone or bamboo and while bristles were fashioned from the hairs from the back of a hog’s neck!

Image 1: Toothbrush with horsehair bristles, London, England,1870-1920. Credit: Science Museum, London, CC BY.

Image 1 shows two toothbrushes that are part of a collection from the Science Museum in London. Both are made by the firm Savory and Moore. Savory and Moore was actually a dispensing chemist, and was the only retail outlet allowed in the district of Belgravia at the time. It served the royal family so it would be reasonable to assume that the owner of these toothbrushes was fairly wealthy. The toothbrush handles are made of ivoride, whilst the bristles are horsehair.

Nylon bristles were first used for toothbrushes in 1938. This new form of toothbrush was rapidly adopted due to growing concerns about oral hygiene during the Second World War. Indeed, the first truly ‘electric’ toothbrush was invented at the end of the 1930s. However, it was deemed ineffective and so sales never really took off. 1954 saw the introduction of ‘Broxodent’, the first usable electric toothbrush. However, this toothbrush was fairly unsafe given its high voltage and the fact that it was typically used in the bathroom where the presence of water further enhanced its electrocution danger! It wasn’t until 1961 that a cordless and rechargeable model of electric toothbrush became available, manufactured by General Electric – this sold much better. The electric toothbrushes that we have today have come a long way: they run on a lower voltage, have improved battery life and are rechargeable.

And the history of toothpaste? Well that’s another story..!

Further reading

‘The History of the Electric Toothbrush,’ accessed 4/8/19. Available at: https://www.electricteeth.co.uk/the-history-of-the-electric-toothbrush/
‘Prison, Suicide, & the Cold-Climate Hog (the sordid history of the toothbrush,’ The Museum of Everyday Life, accessed 4/8/19. Available at: http://museumofeverydaylife.org/exhibitions-collections/previous-exhibitions/toothbrush-from-twig-to-bristle-in-all-its-expedient-beauty/a-visual-history-of-the-toothbrush

Lucy Havard

Joseph Bazalgette (28/3/1819 – 15/3/1891)

Posted on 6th April 20196th April 2019 by Edward Wawrzynczak | Leave a comment

Thames Water, the authority responsible forLondon’s water and sewage system, is currently building a massive new ‘Super Sewer’ known as “Tideway”. Approximately 25km in length and due for completion in 2024, this project is being undertaken to prevent the release of thousands of tons of untreated sewage into the River Thames on a daily basis. This contemporary, complex and sometimes controversial civil engineering project is a reminder of the birth of London’s sewage system, designed by Joseph Bazalgette, born two centuries ago last month.

Portrait of Sir Joseph Bazalgette. Credit: Wellcome Collection. CC BY.

161 years ago Victorian MPs were busy arguing and prevaricating over the cost and necessity (or not) of building and funding a proper purpose-built sewer system, designed by Bazalgette. They rapidly ceased all opposition to the project during the long hot summer of 1858 when low tides meant that huge quantities of untreated sewage that normally ran into the Thames were deposited on the river’s foreshores. The resulting appalling smell became known as “The Great Stink”. Believing, as most did at that time, that bad smells spread disease, MPs had to hang sheets soaked in carbolic against the windows in the Palace of Westminster to stop the suffocating stench. Before finally leaving The House ‘en masse’ the MPs quickly voted in the necessary funding for Joseph Bazalgette’s brilliantly conceived sewer system. It consisted of “intercepting sewers”, pumping stations and treatment works that are still being used today thanks to the high quality brick-lined tunnels and the use of durable Portland cement.

Civil engineering: construction drawings for the Thames Embankment. Coloured drawing, 1865, after Sir J. Bazalgette. Credit: Wellcome Collection. CC BY.

Bazalgette was a brilliant engineer, who started his career working on various railway projects. He was responsible not only for the London Sewer System but also for the Thames Embankment, and numerous major roads in London such as Shaftesbury Avenue and Northumberland Avenue. He strengthened or rebuilt 12 bridges over the Thames and freed them from tolls. He also engineered the Blackwall Tunnel and the Woolwich Ferry, and important parks such as Clissold Park, Finsbury Park and Victoria Park “the green lung of East London”.

However, it is Bazalgette’s sewer system for which he is probably most famous. He designed it anticipating a population increase in London from 2 million to 4 million – extremely far-sighted for the time. Given that the current population of London is approximately 8.5 million, no wonder a ‘Super Sewer’ is needed to provide for the increased strain on the system. More important than saving Londoners from a further ‘Great Stink’, Bazalgette’s work played a critical role in saving the lives of many thousands from deadly water-borne infections such as cholera. For this, he deserves to be remembered.