Emergency Preparedness and Response

Smallpox Preparedness and Response Updates from FDA

What's new | Fast facts | FDA's role | Medical countermeasures | Guidance for industry | Advisory Committee meetings | Consumer protection | Additional resources | Contact FDA

What's new

Fast Facts

  • Variola virus is the causative agent of smallpox
  • Smallpox was declared eradicateddisclaimer icon in 1980 by the World Health Organization, with no known cases of naturally occurring smallpox having occurred since 1977. The last outbreak of smallpox in the United States occurred in 1949.
  • While there is no known immediate, direct threat of a biological attack using smallpox (i.e., an intentional release of Variola virus), concerns over the possible use of Variola virus in a biological attack have led to increased preparedness efforts.
  • Transmission:Smallpox can be transmitted person-to-person via inhalation of virus-containing airborne droplets of saliva from an infected person. Transmission can also occur via contact with material from the smallpox pustules or crusted scabs, or through materials such as bedding or clothing that has been in contact with the pustules or scabs.
  • Prevention: Smallpox can be prevented by vaccination with smallpox vaccine. The vaccine does not contain the smallpox virus and cannot give you smallpox. Also see Vaccines below
  • Treatment: Treatment of patients with smallpox generally involves supportive care. TPOXX (tecovirimat) is approved for the treatment of smallpox. Also see Therapeutics below

FDA's role

FDA plays a critical role in protecting the United States from chemical, biological, radiological, nuclear (CBRN), and emerging infectious disease threats.

FDA's roles in smallpox preparedness and response include:

  • Facilitating the development and availability of medical countermeasures (MCMs) that can be used to diagnose, prevent, or treat smallpox. Also see Medical countermeasures and Guidance for industry below, and What are medical countermeasures?
  • Working with medical product sponsors to clarify regulatory and data requirements necessary to rapidly advance development of MCMs essential to supporting response efforts.
  • Protecting the safety of the nation’s blood supply and human cells, tissues, and cellular/tissue-based products for transplantation. Also see Guidance for industry below
  • Enabling access to investigational MCMs—when necessary—through an appropriate regulatory mechanism such as under an Emergency Use Authorization (EUA) or under expanded access when the clinical circumstances warrant.
  • Protecting consumers against fraudulent products - Unfortunately, during emergency situations, fraudulent products claiming to prevent, treat or cure conditions associated with the emergency almost always appear for sale. The FDA monitors for fraudulent products and false product claims related to CBRN and emerging infectious disease threats and takes appropriate action to protect consumers. Also see Consumer protection below

Medical countermeasures

Vaccines | Therapeutics | Diagnostics


Vaccination against smallpox before contact with the Variola virus can protect you from getting sick. Vaccination within 7 days of being exposed to Variola virus may provide protection from disease and, if you still get smallpox, may reduce the severity of disease. Currently, smallpox vaccine is not available to the general public because smallpox has been eradicated, and the virus no longer exists in nature.

The Strategic National Stockpile (SNS) currently contains three smallpox vaccines:

  • ACAM2000 (Smallpox [Vaccinia] Vaccine, Live) is a replication-competent vaccinia virus vaccine, indicated for active immunization against smallpox disease in persons determined to be at high risk for smallpox infection. This is the only licensed smallpox vaccine in the United States. Also see ACAM2000 (Smallpox Vaccine) Questions and Answers
  • Imvamune (MVA-BN) is an investigational, replication-deficient smallpox vaccine. In a smallpox emergency, Imvamune could potentially be made available under an Investigational New Drug Application (IND) or an EUA for persons with certain immune deficiencies or conditions (such as persons with a diagnosis of HIV or atopic dermatitis).
  • Aventis Pasteur Smallpox Vaccine (APSV) is an investigational, replication-competent vaccinia virus vaccine. In a smallpox emergency, APSV could potentially be made available under an IND or EUA for use in circumstances where ACAM2000 is depleted or not readily available.

Replication-competent vaccinia virus vaccines are generally safe and effective, but some people do experience side effects and adverse reactions. Severe adverse reactions are more common in people who are being vaccinated for the first time and among young children (≤5 years of age). Vaccinia Immune Globulin Intravenous (Human) (VIGIV) is indicated for the treatment and/or modification of certain conditions that are complications resulting from smallpox vaccination with replication-competent vaccinia virus vaccines.

Also see related information about smallpox vaccines, from FDA’s Center for Biologics Evaluation and Research (CBER), and Smallpox Vaccines and Medical Management of Adverse Reactions (information for clinicians) from CDC 


The Strategic National Stockpile (SNS) currently contains two smallpox therapeutics:

  • TPOXX (tecovirimat) is indicated for the treatment of smallpox. This is the only approved smallpox therapeutic in the United States.
  • Cidofovir is an investigational therapeutic for the treatment of smallpox. Cidofovir has not been tested in people with smallpox, and thus it is not known whether a person with smallpox would benefit from treatment with Cidofovir. In a smallpox emergency, Cidofovir could potentially be made available under an IND or EUA for the treatment of smallpox if the circumstances warrant.

Also see Medical Management of Adverse Reactions from CDC, which includes information for clinicians on how to obtain VIGIV and antivirals.


Diagnosis of initial cases of smallpox in a smallpox emergency would likely be based on clinical diagnosis confirmed by follow-up laboratory testing. Laboratory diagnostic testing for Variola virus would occur in a CDC Laboratory Response Network (LRN) laboratory using specialized diagnostic tests and protocols for Variola virus.

Cleared Variola virus diagnostic tests:

Guidance for industry
Advisory Committee meetings
  • May 1, 2018: The Antimicrobial Drugs Advisory Committee met to discuss the new drug application (NDA) 208627 for TPOXX (tecovirimat), sponsored by SIGA Technologies Inc., for the proposed indication of the treatment of smallpox disease caused by Variola virus in adults and pediatric patients. Meeting materials, including briefing information and minutes are available.
Consumer protection

Unfortunately, during outbreak situations, fraudulent products claiming to prevent, treat or cure a disease almost always appear. The FDA monitors for fraudulent products and false product claims related to smallpox and takes appropriate action to protect consumers.

Fraudulent product updates and warning letters
Additional resources
Contact FDA

Consumers and general information: contact FDA
You may also call 1-888-INFO-FDA / (1-888-463-6332)

Report a fraudulent smallpox product
Includes options for phone and online reporting

Press: contact the Office of Media Affairs
Email fdaoma@fda.hhs.gov or call 301-796-4540

Contact FDA’s Medical Countermeasures Initiative (MCMi)
AskMCMi@fda.hhs.gov, 301-796-8510

Page Last Updated: 12/18/2018
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