cowpox which produced the desired result and 'spurious' cowpox which was ineffective and/or produced severe reaction. modern research suggests jenner was trying to distinguish between effects caused by what would now be recognised as non-infectious vaccine, a different virus (e.g. paravaccinia/milker's nodes), or contaminating bacterial pathogens. this caused confusion at the time, but would become important criteria in vaccine development. a further source of confusion was jenner's belief that fully effective vaccine obtained from cows originated in an equine disease, which he mistakenly referred to as grease. this was criticised at the time but vaccines derived from horsepox were soon introduced and later contributed to the complicated problem of the origin of vaccinia virus, the virus in present-day vaccine.: 165–78 the introduction of the vaccine to the new world took place in trinity, newfoundland, in 1798 by dr. john clinch, boyhood friend and medical colleague of jenner. the first smallpox vaccine in the united states was administered in 1799. the physician valentine seaman gave his children a smallpox vaccination using a serum acquired from jenner. by 1800, jenner's work had been published in all the major european languages and had reached benjamin waterhouse in the united states – an indication of rapid spread and deep interest.: 262–67 despite some concern about the safety of vaccination the mortality using carefully selected vaccine was close to zero, and it was soon in use all over europe and the united states. the balmis expedition took the vaccine to spanish america in 1804. in 1804 the balmis expedition, an official spanish mission commanded by francisco javier de balmis, sailed to spread the vaccine throughout the spanish empire, first to the canary islands and on to spanish central america. while his deputy, josé salvany, took vaccine to the west and east coasts of spanish south america, balmis sailed to manila in the philippines and on to canton and macao on the chinese coast. he returned to spain in 1806. the vaccine was not carried in the form of flasks, but in the form of 22 orphaned boys, who were 'carriers' of the live cowpox virus. after arrival, "other spanish governors and doctors used enslaved girls to move the virus between islands, using lymph fluid harvested from them to inoculate their local populations". the first state to introduce compulsory vaccinations was the principality of lucca and piombino on september 25, 1806. on august 26, 1807, bavaria introduced a similar measure. baden followed in 1809, prussia in 1815, württemberg in 1818, sweden in 1816, england in 1867 and the german empire in 1874 through the reichs vaccination act. in lutheran sweden, the protestant clergy played a pioneering role in voluntary smallpox vaccination as early as 1800. the first vaccination was carried out in liechtenstein in 1801, and from 1812 it was mandatory to vaccinate. the question of who first tried cowpox inoculation/vaccination cannot be answered with certainty. most, but still limited, information is available for benjamin jesty, peter plett and john fewster. in 1774 jesty, a farmer of yetminster in dorset, observing that the two milkmaids living with his family were immune to smallpox, inoculated his family with cowpox to protect them from smallpox. he attracted a certain amount of local criticism and ridicule at the time then interest waned. attention was later drawn to jesty, and he was brought to london in 1802 by critics jealous of jenner's prominence at a time when he was applying to parliament for financial reward. during 1790–92 peter plett, a teacher from holstein, reported limited results of cowpox inoculation to the medical faculty of the university of kiel. however, the faculty favoured variolation and took no action. john fewster, a surgeon friend of jenner's from nearby thornbury, discussed the possibility of cowpox inoculation at meetings as early as 1765. he may have done some cowpox inoculations in 1796 at about the same time that jenner vaccinated phipps. however, fewster, who had a flourishing variolation practice, may have considered this option but used smallpox instead. he thought vaccination offered no advantage over variolation, but maintained friendly contact with jenner and certainly made no claim of priority for vaccination when critics attacked jenner's reputation. it seems clear that the idea of using cowpox instead of smallpox for inoculation was considered, and actually tried in the late 18th century, and not just by the medical profession. therefore, jenner was not the first to try cowpox inoculation. however, he was the first to publish his evidence and distribute vaccine freely, provide information on selection of suitable material, and maintain it by arm-to-arm transfer. the authors of the official world health organization (who) account smallpox and its eradication assessing jenner's role wrote:: 264 publication of the inquiry and the subsequent energetic promulgation by jenner of the idea of vaccination with a virus other than variola virus constituted a watershed in the control of smallpox for which he, more than anyone else deserves the credit. as vaccination spread, some european countries made it compulsory. concern about its safety led to opposition and then repeal of legislation in some instances.: 236–40 compulsory infant vaccination was introduced in england by the 1853 vaccination act. by 1871, parents could be fined for non-compliance, and then imprisoned for non-payment.: 202–13 this intensified opposition, and the 1898 vaccination act introduced a conscience clause. this allowed exemption on production of a certificate of conscientious objection signed by two magistrates. such certificates were not always easily obtained and a further act in 1907 allowed exemption by a statutory declaration which could not be refused. although theoretically still compulsory, the 1907 act effectively marked the end of compulsory infant vaccination in england.: 233–38 1919 notice issued by the british general post office encouraging postal staff to apply for the free vaccination. in the united states vaccination was regulated by individual states, the first to impose compulsory vaccination being massachusetts in 1809. there then followed sequences of compulsion, opposition and repeal in various states. by 1930 arizona, utah, north dakota and minnesota prohibited compulsory vaccination, 35 states allowed regulation by local authorities, or had no legislation affecting vaccination, whilst in ten states, including washington, d.c. and massachusetts, infant vaccination was compulsory.: 292–93 compulsory infant vaccination was regulated by only allowing access to school for those who had been vaccinated. those seeking to enforce compulsory vaccination argued that the public good overrode personal freedom, a view supported by the u.s. supreme court in jacobson v. massachusetts in 1905, a landmark ruling which set a precedent for cases dealing with personal freedom and the public good. louis t. wright, an african-american harvard medical school graduate (1915), introduced, while serving in the army during world war i, intradermal, smallpox vaccination for the soldiers. 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; 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. 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. 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,: 122 some critics of vaccination e.g. charles creighton believed that uncontaminated vaccine itself was a cause of syphilis. 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. sydney arthur monckton copeman, an english government bacteriologist interested in smallpox vaccine investigated the effects on the bacteria in it of various treatments, including 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. 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. in 1896, copeman was asked to supply "extra good calf vaccine" to vaccinate the future edward viii. vaccine produced by copeman's method was the only type issued free to public vaccinators by the english government vaccine establishment from 1899. at the same time the 1898 vaccination act banned arm-to-arm vaccination, thus preventing transmission of syphilis by this vaccine. however, private practitioners had to purchase vaccine from commercial producers. 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. the level of bacterial contamination remained unregulated until the therapeutic substances act, 1925 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. unfortunately glycerolated vaccine soon lost its potency at ambient temperatures which restricted its use in tropical climates. however, it remained in use into the 1970s where 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.: 543–45 english vaccine was occasionally made in sheep during world war i but from 1946 only sheep were used. 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. 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 37 °c (99 °f) 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.: 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". 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. 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. 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.: 472–73, 568–72 rubin estimated that it was used to do 200 million vaccinations per year during the last years of