Smallpox vaccine

Smallpox vaccine, the first successful vaccine to be developed, was introduced by Edward Jenner in 1796. He followed up his observation that milkmaids who had previously caught cowpox did not later catch smallpox by showing that inoculated cowpox protected against inoculated smallpox. Dryvax is a freeze-dried calf lymph smallpox vaccine. It is the world's oldest smallpox vaccine, created in the late 19th century by American Home Products, a predecessor of Wyeth. By the 1940s, Wyeth was the leading US manufacturer of the vaccine and the only manufacturer by the 1960s. After world health authorities declared smallpox had been eradicated from nature in 1980, Wyeth stopped making the vaccine. The US Centers for Disease Control and Prevention (CDC) kept a stockpile for use in case of emergency. In 2003 this supply helped contain an outbreak of monkeypox in the United States. In February 2008 the CDC disposed of the last of its 12 million doses of Dryvax. Its supply is being replaced by ACAM2000, a more modern product manufactured in laboratories by Acambis, now a division of Sanofi Pasteur. Dryvax is a live-virus preparation of vaccinia prepared from calf lymph. Trace amounts of the following antibiotics (added during processing) may be present: neomycin sulfate, chlortetracycline hydrochloride, polymyxin B sulfate, and dihydrostreptomycin sulfate. The vaccine is effective, providing successful immunogenicity in about 95% of vaccinated persons. Dryvax has serious adverse side-effects in about 1% to 2% of cases. ACAM2000 is a smallpox vaccine developed by Acambis. It was approved for use in the United States by the U.S. Food and Drug Administration (FDA) on 31 August 2007. It contains live vaccinia virus, cloned from the same strain used in an earlier vaccine, Dryvax. While the Dryvax virus was cultured in the skin of calves and freeze-dried, ACAM2000s virus is cultured in kidney epithelial cells (Vero cells) from an African green monkey. Efficacy and adverse reaction incidence are similar to Dryvax. The vaccine is not routinely available to the US public; it is, however, used in the military and maintained in the Strategic National Stockpile. A droplet of ACAM2000 is administered by the percutaneous route (scarification) using 15 jabs of a bifurcated needle. ACAM2000 should not be injected by the intradermal, subcutaneous, intramuscular, or intravenous route. Calf lymph was the name given to a type of smallpox vaccine used in the 19th century, and which was still manufactured up to the 1970s. Calf lymph was known as early as 1805 in Italy, but it was the Lyon Medical Conference of 1864 which made the technique known to the wider world. In 1898 calf lymph became the standard method of vaccination for smallpox in the United Kingdom, when arm-to-arm vaccination was eventually banned (due to complications such as the simultaneous transmission of syphilis).