Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
About Smallpox
Smallpox is a disease caused by the Variola major virus. Some experts say that over the centuries it has killed more people than all other infectious diseases combined. Worldwide vaccination stopped the spread of smallpox three decades ago. The last case was reported in 1977. Two research labs still keep small amounts of the virus. Experts fear bioterrorists could use the virus to spread disease.
Smallpox spreads very easily from person to person. Symptoms are flu-like. They include:
- High fever
- Fatigue
- Headache
- Backache
- A rash with flat red sores
There is no treatment. Fluids and medicines for pain or fever can help control symptoms. Most people recover, but some can die. Those who do recover may have severe scars.
The U.S. stopped routine smallpox vaccinations in 1972. Military and other high-risk groups continue to get the vaccine. The U.S. has increased its supply of the vaccine in recent years. The vaccine makes some people sick, so doctors save it for those at highest risk of disease.
It sits within Infections and Poisoning, Toxicology, Environmental Health.
The lead U.S. institute for this subject is the National Institute of Allergy and Infectious Diseases.
When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.
Research on Smallpox
88 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.
What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.
Research currently under way
- A Randomized Clinical Trial Investigating the Safety, Reactogenicity, and Immunogenicity After Immunization With an mRNA-based Mpox Vaccine Candidate in AfricaBioNTech SE
- Tecovirimat (ST-246) Treatment for Orthopox Virus ExposureU.S. Army Medical Research and Development Command
- VA-005 Clinical Outcomes of VIGIV Treatment of Smallpox Vaccination Complications or Vaccinia InfectionEmergent BioSolutions
- Phase 3 Infant Safety & Immunogenicity Trial of MVA-BN® in DRCJean-Pierre Van geertruyden
- Study to Assess the Safety and Immunogenicity of TPOXX® When Administered Orally for 28 Days With JYNNEOSSIGA Technologies
- Prospective Study for the FOLLOW-UP of Human Monkeypox Cases and Smallpox Vaccinees at RiskInstitute of Tropical Medicine, Belgium
Research already completed
- JYNNEOS Smallpox Vaccine in Adult Healthcare Personnel at Risk for Mpox in the Democratic Republic of the CongoCenters for Disease Control and Prevention
- MVA Post-Event: Administration Timing and Boost StudyNational Institute of Allergy and Infectious Diseases (NIAID)
- A Study to Investigate The Safety, Tolerability, And Immune Response of a Range of Doses of mRNA-1769 Compared With Placebo in Healthy Participants From ≥18 Years of Age to <50 Years of AgeModernaTX, Inc.
- High Dose IMVAMUNE® in Vaccinia-Naive IndividualsNational Institute of Allergy and Infectious Diseases (NIAID)
- Study Evaluating the Bioequivalence of Brincidofovir Form H and Form II Tablets in Healthy AdultsEmergent BioSolutions
- Safety, Tolerability and Pharmacokinetics of TPOXX When Administered Orally for 28 DaysSIGA Technologies
Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.
Where to read more
Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.
Start Here
- About SmallpoxCenters for Disease Control and Prevention
- Questions and Answers on SmallpoxWorld Health Organization
- SmallpoxMayo Foundation for Medical Education and Research
- SmallpoxNational Institute of Allergy and Infectious Diseases
Symptoms
- Signs and Symptoms of SmallpoxCenters for Disease Control and Prevention
Prevention and Risk Factors
- Smallpox VaccineCenters for Disease Control and Prevention
- Smallpox vaccine: What are the risks if someone has eczema?American Academy of Dermatology
Statistics and Research
- Smallpox ResearchCenters for Disease Control and Prevention
Clinical Trials
- ClinicalTrials.gov: SmallpoxNational Institutes of Health
Patient Handouts
- Smallpox/Monkeypox Vaccine (JYNNEOS): What You Need to KnowCenters for Disease Control and Prevention
Medical subject headings
Clinicians and researchers index this subject under Smallpox, Smallpox Vaccine. These are the terms to use when searching medical literature.
This page is built from the MedlinePlus health topic record for Smallpox, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.