Dryvax is a freeze-dried calf lymph

Calf lymph

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.-History:...

 smallpox

Smallpox

Smallpox was an infectious disease unique to humans, caused by either of two virus variants, Variola major and Variola minor. The disease is also known by the Latin names Variola or Variola vera, which is a derivative of the Latin varius, meaning "spotted", or varus, meaning "pimple"...

 vaccine

Vaccine

A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...

. It is the world's oldest smallpox vaccine, created in the late 19th century by American Home Products, a predecessor of Wyeth

Wyeth

Wyeth, formerly one of the companies owned by American Home Products Corporation , was a pharmaceutical company. The company was based in Madison, New Jersey, USA...

. By the 1940s, Wyeth was the leading US

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 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

Centers for Disease Control and Prevention

The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...

 (CDC) kept a stockpile of the drug to use in case of emergency. In 2003 this supply helped contain an outbreak of monkeypox

Monkeypox

Monkeypox also known as cockpox is an exotic infectious disease caused by the monkeypox virus. The disease was first identified in laboratory monkeys, hence its name, but in its natural state it seems to infect rodents more often than primates...

 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

ACAM2000

ACAM2000 is a smallpox vaccine developed by . It was approved for use in the United States by the U.S. Food and Drug Administration on 31 August 2007. It contains live vaccinia virus, cloned from the same strain used in an earlier vaccine, Dryvax...

, a more modern product manufactured in laboratories by Acambis, now a division of Sanofi Pasteur

Sanofi pasteur

Sanofi Pasteur is the vaccines division of sanofi-aventis Group. It is the largest company in the world devoted entirely to vaccines.- History :...

.

Dryvax is a live-virus preparation of vaccinia

Vaccinia

Vaccinia virus is a large, complex, enveloped virus belonging to the poxvirus family. It has a linear, double-stranded DNA genome approximately 190 kbp in length, and which encodes for approximately 250 genes. The dimensions of the virion are roughly 360 × 270 × 250 nm, with a mass of...

 prepared from calf lymph. Trace amounts of the following antibiotics (added during processing) may be present: neomycin sulfate, chlortetracycline hydrochloride, polymyxin

Polymyxin

Polymyxins are antibiotics, with a general structure consisting of a cyclicpeptide with a long hydrophobic tail. They disrupt the structure of thebacterial cell membrane by interacting with its phospholipids...

 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.