FDA approves Acambis smallpox vaccine

Acambis plc (Acambis) has announced that the US Food and Drug Administration (FDA) has approved its ACAM2000 (Smallpox (Vaccinia) Vaccine, Live) vaccine for protection against smallpox.

The vaccine is intended for active immunization against smallpox disease for persons determined to be at high risk for smallpox infection. ACAM2000 is the first biodefense vaccine to be approved as part of the US response to the 2001 bioterrorism attacks.

Acambis developed ACAM2000 under contracts with the US Centers for Disease Control and Prevention (CDC). To date, Acambis has supplied 192.5 million doses of ACAM2000 to the CDC for the US Strategic National Stockpile (SNS), which was established to provide medicines to the American public in the event of a public health emergency, such as a terrorist attack.

Having produced a stockpile of ACAM2000 doses for the SNS, Acambis and the CDC are now in advanced discussions on a "warm-base manufacturing" contract for Acambis to provide ACAM2000 production and license maintenance activities for the long term.

Ian Garland, Acambis Chief Executive Officer, said: "The licensure of ACAM2000 is a significant milestone not only for Acambis but also for the US Government in its efforts to ensure a state of preparedness against the threat of smallpox. This has been a highly successful collaboration between Acambis and the CDC, and Acambis is very proud to have played a role in providing this countermeasure against a significant bioterrorism threat. We look forward to finalizing an agreement with the CDC that will ensure that a US-based capability to manufacture ACAM2000 remains at the ready."

ACAM2000 was developed to be a modern smallpox vaccine with a safety and efficacy profile comparable to the previous US vaccine but manufactured using advanced production capabilities. Until the development of ACAM2000, smallpox vaccines were last manufactured in the US in 1982 and were produced from calf lymph.

ACAM2000, which is a single-dose vaccine, is the primary smallpox vaccine for use in an emergency and forms the majority of the US Government's smallpox vaccine stockpile.

The clinical trials data generated on ACAM2000 were reviewed by the FDA Vaccines and Related Biological Products Advisory Committee in May 2007, which voted unanimously (11-0) in favor of the vaccine's safety and efficacy. In addition to being stockpiled for emergency use, ACAM2000 will be used by the US Department of Defense for protection of military personnel.

Important safety information

ACAM2000 may not protect all persons exposed to smallpox. ACAM2000 is contraindicated for individuals with severe immunodeficiency who are not expected to benefit from the vaccine. These individuals may include persons who are undergoing bone marrow transplantation or persons with primary or acquired immunodeficiency states who require isolation.

• The most serious adverse events associated with smallpox vaccination are myocarditis, pericarditis, encephalitis, encephalomyelitis, encephalopathy, progressive vaccinia, generalized vaccinia, severe vaccinial skin infections, and erythema multiforme major (including STEVENS-JOHNSON SYNDROME) and eczema vaccinatum resulting in permanent sequelae or death, ocular complications, blindness, and fetal death have occurred following either primary vaccination or revaccination with smallpox vaccines.
• The most common side effects following smallpox vaccination include itching, swollen lymph nodes, sore arm, fever, headache, body ache, mild rash, and fatigue.

Full prescribing information may be obtained by calling Acambis at +1-866-440-9440 (toll free) or +1-617-866-4500.

Smallpox is a highly contagious disease caused by the variola virus, a member of the Orthopox virus family. It is one of the most devastating diseases known to humanity, with a mortality rate as high as 30%. In 1967, the World Health Organization embarked upon an intensified vaccination campaign to eliminate smallpox, which culminated in the successful eradication of the disease globally by 1980.(1)

By the mid-1980s, there were only two known repositories of variola virus: the Institute of Virus Preparations in Russia, and the US CDC. The events in the US in September and October 2001 highlighted the risk that the variola virus might be used as an agent of bioterrorism.(2) Governments around the world are taking precautionary measures to be ready to deal with a potential smallpox outbreak.

About ACAM2000

• ACAM2000 is a live, vaccinia virus smallpox vaccine indicated for active immunization against smallpox disease for persons determined to be at high risk for smallpox infection.
• It is a single-dose vaccine administered percutaneously.
• It was derived by plaque purification from Dryvax(R), the licensed calf lymph-produced vaccine that was extensively used in the smallpox eradication program.
• ACAM2000 is manufactured in Vero cells using modern cell-culture techniques designed to comply with current Good Manufacturing Practice standards.
• Acambis has supplied more than 200 million doses of ACAM2000 under an FDA Investigational New Drug application to 15 governments around the world, including the US.

Notes and references

(1) WHO: http://www.who.int/mediacentre/factsheets/smallpox/en/

(2) CDC: http://www.bt.cdc.gov/agent/smallpox/overview/disease-facts.asp