Smallpox
    Diagnosis and treatment

    March 19, 2026

    Diagnosis

    There are special labs that test tissue samples to diagnose smallpox. But if a smallpox outbreak happened today, many healthcare professionals might not be able to diagnose the virus in its early stages because they've never seen it. This could allow the smallpox virus to spread.

    Even one person with smallpox would be a public health emergency.

    Treatment

    The U.S. Food and Drug Administration, also called FDA, has approved antiviral medicines to treat smallpox. These include:

    • Tecovirimat (Tpoxx). The FDA approved this medicine for use in the U.S. in 2018. Research found that it worked in animals and in lab tests. But it hasn't been tested in people who have smallpox. So experts don't know if it works for smallpox. A study of the medicine in people with no health concerns found it to be safe.
    • Brincidofovir (Tembexa). The FDA approved this drug in 2021 for use in the U.S. Researchers have tested brincidofovir in animals and in labs. It has not been tested in people who have smallpox. People who aren't ill and people who have other viruses have used it safely.

    Infectious Diseases Care at Mayo Clinic

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    1. Friedman HM, et al. Variola virus (smallpox). https://www.uptodate.com/contents/search. Accessed March 28, 2025.
    2. Smallpox. Centers for Disease Control and Prevention. https://www.cdc.gov/smallpox/about/index.html Accessed March 28, 2025.
    3. AskMayoExpert. Smallpox. Mayo Clinic; 2024.
    4. Smallpox in adult. VisualDx. https://www.visualdx.com. Accessed March 28, 2025.
    5. Breman JG. Smallpox. The Journal of Infectious Diseases. 2021; doi:10.1093/infdis/jiaa588.

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