Editing Smallpox vaccine (section)

===Developments in production===

Until the end of the 19th century, vaccination was performed either directly with vaccine produced on the skin of calves or, particularly in England, with vaccine obtained from the calf but then maintained by arm-to-arm transfer;<ref name=Copeman1898>{{cite journal | vauthors = Copeman SM | title = The Milroy Lectures on the Natural History of Vaccina: Delivered at the Royal College of Physicians | journal = British Medical Journal | volume = 1 | issue = 1951 | pages = 1312–1318 | date = May 1898 | pmid = 20757828 | pmc = 2411485 | doi = 10.1136/bmj.1.1951.1312 }}</ref> initially in both cases vaccine could be dried on ivory points for short-term storage or transport but increasing use was made of glass capillary tubes for this purpose towards the end of the century.<ref name=Dudgeon1963>{{cite journal | vauthors = Didgeon JA | title = Development of Smallpox Vaccine in England in the Eighteenth and Nineteenth Centuries | journal = British Medical Journal | volume = 1 | issue = 5342 | pages = 1367–1372 | date = May 1963 | pmid = 20789814 | pmc = 2124036 | doi = 10.1136/bmj.1.5342.1367 }}</ref> During this period there were no adequate methods for assessing the safety of the vaccine and there were instances of contaminated vaccine transmitting infections such as erysipelas, tetanus, septicaemia and tuberculosis.<ref name=Baxby2001/> In the case of arm-to-arm transfer there was also the risk of transmitting syphilis. Although this did occur occasionally, estimated as 750 cases in 100 million vaccinations,<ref name = "Bazin_2000" />{{rp|122}} some critics of vaccination e.g. [[Charles Creighton (physician)|Charles Creighton]] believed that uncontaminated vaccine itself was a cause of syphilis.<ref>{{cite book| vauthors = Creighton C |title=The Natural History of Cowpox and Vaccinal Syphilis|year=1887|publisher=Cassell|location=London}}</ref> Smallpox vaccine was the only vaccine available during this period, and so the determined opposition to it initiated a number of [[vaccine controversies]] that spread to other vaccines and into the 21st century.{{citation needed|date=July 2020}}

[[Sydney Arthur Monckton Copeman]], an English Government bacteriologist interested in smallpox vaccine, investigated the effects on the bacteria in it of various treatments, including [[Glycerol|glycerine]]. Glycerine was sometimes used simply as a [[diluent]] by some continental vaccine producers. However, Copeman found that vaccine suspended in 50% chemically pure glycerine and stored under controlled conditions contained very few "extraneous" bacteria and produced satisfactory vaccinations.<ref>{{cite book|title=Transactions of the Seventh International Congress of Hygiene and Demography|year=1892|publisher=Eyre and Spottiswoode|pages=319–26| vauthors = Copeman SM |chapter=The Bacteriology of Vaccine Lymph| veditors = Shelley CE |chapter-url=https://archive.org/details/transactionssev09shelgoog|access-date=14 January 2014}}</ref> He later reported that glycerine killed the causative organisms of erysipelas and tuberculosis when they were added to the vaccine in "considerable quantity", and that his method was widely used on the continent.<ref name=Copeman1898/> In 1896, Copeman was asked to supply "extra good calf vaccine" to vaccinate the future [[Edward VIII]].<ref>{{cite journal | vauthors = Copeman PW | title = Extinction of the speckled monster celebrated in 1996 | journal = Journal of Medical Biography | volume = 6 | issue = 1 | pages = 39–42 | date = February 1998 | pmid = 11619875 | doi = 10.1177/096777209800600108 | s2cid = 8918951 }}</ref>

Vaccine produced by Copeman's method was the only type issued free to public vaccinators by the British Government Vaccine Establishment from 1899. At the same time the [[Vaccination Act 1898]] ([[61 & 62 Vict.]] c. 49) banned arm-to-arm vaccination, thus preventing transmission of syphilis by this vaccine. However, private practitioners had to purchase vaccine from commercial producers.<ref>{{cite book| vauthors = Dixon CW |title=Smallpox|year=1962|publisher=J. & A. Churchill|location=London|pages=280–81}}</ref> Although proper use of glycerine reduced bacterial contamination considerably the crude starting material, scraped from the skin of infected calves, was always heavily contaminated and no vaccine was totally free from bacteria. A survey of vaccines in 1900 found wide variations in bacterial contamination. Vaccine issued by the Government Vaccine Establishment contained 5,000 bacteria per gram, while commercial vaccines contained up to 100,000 per gram.<ref>{{cite journal| author = Special Commission|title=Report of the Lancet Special Commission on Glycerinated Calf Lymph Vaccines|journal=Lancet|year=1900|volume=155|issue=4000|pages=1227–36|doi=10.1016/s0140-6736(01)96895-3}}</ref> The level of bacterial contamination remained unregulated until the [[Therapeutic Substances Act 1925]] ([[15 & 16 Geo. 5]]. c. 60) set an upper limit of 5,000 per gram, and rejected any batch of vaccine found to contain the causative organisms of erysipelas or wound infections.<ref name=Baxby2001/> Unfortunately glycerolated vaccine lost its potency quickly at ambient temperatures which restricted its use in tropical climates. However, it remained in use into the 1970s when a satisfactory [[cold chain]] was available. Animals continued to be widely used by vaccine producers during the smallpox eradication campaign. A WHO survey of 59 producers, some of whom used more than one source of vaccine, found that 39 used calves, 12 used sheep and 6 used water buffalo, whilst only 3 made vaccine in cell culture and 3 in embryonated hens' eggs.<ref name = "Fenner_1988" />{{rp|543–45}} English vaccine was occasionally made in sheep during World War I but from 1946 only sheep were used.<ref name=Dudgeon1963/>

In the late 1940s and early 1950s, [[Leslie Collier]], an English microbiologist working at the [[Lister Institute of Preventive Medicine]], developed a method for producing a heat-stable freeze-dried vaccine in powdered form.<ref>{{cite journal | vauthors = Collier LH | title = The development of a stable smallpox vaccine | journal = The Journal of Hygiene | volume = 53 | issue = 1 | pages = 76–101 | date = March 1955 | pmid = 14367805 | pmc = 2217800 | doi = 10.1017/S002217240000053X }}</ref><ref>{{cite news|title=Professor Leslie Collier|work=The Telegraph|access-date=2 May 2013|date=22 March 2011|url=https://www.telegraph.co.uk/news/obituaries/8399116/Professor-Leslie-Collier.html |archive-url=https://ghostarchive.org/archive/20220112/https://www.telegraph.co.uk/news/obituaries/8399116/Professor-Leslie-Collier.html |archive-date=12 January 2022 |url-access=subscription |url-status=live}}{{cbignore}}</ref> Collier added 0.5% [[phenol]] to the vaccine to reduce the number of bacterial contaminants but the key stage was to add 5% [[peptone]] to the liquid vaccine before it was dispensed into ampoules. This protected the virus during the freeze drying process. After drying, the ampoules were sealed under nitrogen. Like other vaccines, once reconstituted it became ineffective after 1–2 days at ambient temperatures. However, the dried vaccine was 100% effective when reconstituted after 6 months storage at {{convert|37|°C}} allowing it to be transported to, and stored in, remote tropical areas. Collier's method was increasingly used and, with minor modifications, became the standard for vaccine production adopted by the WHO Smallpox Eradication Unit when it initiated its global smallpox eradication campaign in 1967, at which time 23 of 59 manufacturers were using the Lister strain.<ref name = "Fenner_1988" />{{rp|545, 550}}

In a letter about landmarks in the history of smallpox vaccine, written to and quoted from by [[Derrick Baxby]], [[Donald Henderson]], chief of the Smallpox Eradication Unit from 1967 to 1977 wrote; "Copeman and Collier made an enormous contribution for which neither, in my opinion ever received due credit".<ref>{{cite journal | vauthors = Baxby D | title = Development of a stable smallpox vaccine: Collier L. J Hyg 1955; 53: 76–101 | journal = Epidemiology and Infection | volume = 133 | issue = Suppl. 1 | pages = S25–S27 | date = October 2005 | pmid = 24965243 | doi = 10.1017/S0950268805004280 | doi-access = free | title-link = doi }}</ref>

Smallpox vaccine was inoculated by scratches into the superficial layers of the skin, with a wide variety of instruments used to achieve this. They ranged from simple needles to multi-pointed and multi-bladed spring-operated instruments specifically designed for the purpose.<ref>{{cite book| vauthors = Kirkup JR |title=The Evolution of Surgical Instruments|year=2006|publisher=Norman Publishing|location=Novato, California|isbn=978-0-930405-86-1|pages=419–37}}</ref>

A major contribution to smallpox vaccination was made in the 1960s by [[Benjamin Rubin]], an American microbiologist working for [[Wyeth]] Laboratories. Based on initial tests with textile needles with the eyes cut off transversely half-way he developed the [[bifurcated needle]]. This was a sharpened two-prong fork designed to hold one dose of reconstituted freeze-dried vaccine by capillarity.<ref name=Rubin1980>{{cite journal | vauthors = Rubin BA | title = A note on the development of the bifurcated needle for smallpox vaccination | journal = WHO Chronicle | volume = 34 | issue = 5 | pages = 180–181 | date = May 1980 | pmid = 7376638 }}</ref> Easy to use with minimum training, cheap to produce ($5 per 1000), using one quarter as much vaccine as other methods, and repeatedly re-usable after flame sterilization, it was used globally in the WHO Smallpox Eradication Campaign from 1968.<ref name = "Fenner_1988" />{{rp|472–73, 568–72}} Rubin estimated that it was used to do 200 million vaccinations per year during the last years of the campaign.<ref name=Rubin1980/> Those closely involved in the campaign were awarded the "Order of the Bifurcated Needle". This, a personal initiative by Donald Henderson, was a lapel badge, designed and made by his daughter, formed from the needle shaped to form an "O". This represented "Target Zero", the objective of the campaign.<ref>{{cite book| vauthors = Henderson DA |title=Smallpox; the death of a disease|year=2009|publisher=Prometheus Books|location=Amherst, New York|isbn=978-1-59102-722-5|pages=26–27}}</ref>