Smallpox Symptoms, Prevention & Treatment [2024]

Smallpox is caused by the variola virus that is highly contagious and deadly.

Symptoms are fever and a skin rash that progresses over the course of the infection.

Seventy percent of people recover, but 30% died.

Those that survive smallpox have scars (permanent) on most of their body and face.

Occasionally, some survivors are blind.

Today, smallpox has not been an issue in the United States, thanks to vaccination.

Last natural outbreak of smallpox globally was in 1977, for the US it was 1949.

Transmission of Smallpox

Transmission between people usually is from physical touch, body fluids and droplets from sneezing & coughing.

Smallpox is spread only by human to human, it is not spread by animals or insects.

Early stage of smallpox are sores in the mouth and throat. This allows the virus to spread through droplets from coughing and sneezing in close contact to other people.

Face to face contact between individuals allow for smallpox to easily spread.

Sores and scabs with fluid contain the variola virus, which can easily spread through clothing and bedding.

It is important to wear gloves for those that cared for smallpox patients, so they do not get infected.

Smallpox is contagious until the last scab falls off.

Signs and Symptoms

smallpox signs and symptoms

There are several stages of progression of smallpox and each stage is different.

First stage – Incubation period 7 to 19 days

Not contagious.

  • this stage is usually 10 to 14 days on average
  • there are no symptoms
  • infected person usually feels fine

Second Stage – Sign of symptoms 2 to 4 days

Can be contagious during this period but not always.

  • headaches
  • bodyaches
  • high fever
  • nausea (sometimes)
  • vomiting (sometimes)

The infected person is not well and usually rests.

smallpox most contagious period 4th stage

Third Stage – Early rash – lasts about 4 days

Most contagious stage.

Starts in the mouth and tongue with small red spots, these spots become sores.

Sores then break and spread the virus further in to the mouth and throat.

High fever continues.

Within 24 hours, the rash spreads to the face, arms, legs, hands and feet.

Reduction in fever happens and the person may feel better.

The fourth day, the sores have thick fluid and a dent in the center.

At this point, high fever maybe expected until scabs form over the fluid filled skin sores.

Fourth Stage – Pustular Rash and Scabs – lasts 10 days

Still very contagious.

The skin sores become like peas under the skin, called pustules.

Pustules become crusty and then form a scab after 5 days.

In to the 2nd week after the rash began, the sores on the skin have scabbed over.

Fifth Stage – Scabs fall off – lasts 6 days

Still contagious.

Scabs now are beginning to fall off and leave marks on the skin

3 weeks after the first sign of rash began, scabs should have fallen off.

Sixth Stage – No scabs

Not contagious at this time.

All scabs should have fallen off, it has been 4 weeks since the first sign of rash appeared.

Person is no longer contagious after all scabs have fallen off.

smallpox prevention and treatment

Prevention and treatment

Vaccines are available to prevent people from getting smallpox.

Because this disease is eradicated, the public is no longer administered the vaccine.

As of now there is no treatment for smallpox that has been tested on people with the disease.


Vaccinia virus vaccines can be used to prevent smallpox.

Smallpox virus is similar to vaccinia virus, both are poxviruses.

However, vaccinia virus is less harmful and so it is used as a vaccine.

There are two smallpox vaccines approved by the FDA:

These vaccines can help you:

  • not get sick before contact with the virus.
  • can protect you from getting disease if you have been exposed to the virus within 3 days
  • can give you some protection if you have been exposed to the virus between 4 to 7 days
  • no protection once you have smallpox rash

US government stockpiles vaccines, so every person in the country can be vaccinated.

antiviral drugs

Antiviral Drugs

As previously mentioned these drugs have not been tested on people with smallpox.

They have been given to healthy people that do not have smallpox. Side effects are few if any and considered overall safe.

The Assistant Secretary for Preparedness and Response (ASPR), a US Federal government office, stock piles cidofovir and tecovirimat for potential outbreaks of smallpox.

Please refer to ASPR website regarding the monkeypox outbreak here.