Smallpox In Children: Causes, Symptoms, Treatment And Vaccine

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Smallpox was a severe infectious disease of the past. The last outbreak happened in 1949, and the last natural spread of smallpox disease was reported in 1977. Smallpox was eradicated globally in 1980 (1). A single confirmed case today would be considered a health emergency due to its severity and contagious nature.

Smallpox vaccine is not given to the general population since there is no longer the threat of the disease. However, due to the possibility of using the variola virus (the virus that causes smallpox )as a biological weapon, many countries have smallpox preparedness programs and vaccines ready for emergencies (2).

Read this post to know more about the causes, symptoms, risk factors, diagnosis, treatment, and prevention of the deadly infectious disease contracted by humankind in the past.

Causes Of Smallpox In Children

Smallpox was caused by the variola virus (VARV), which belongs to the genus orthopoxvirus. Variola virus occurred in the following two forms (3).

  • Variola major: This was the most common and severe form that caused high fever and extensive skin rash.
  • Variola minor: This form of variola virus caused less severe disease with fewer death rates than variola major.

Although asymptomatic or subclinical infections were seen, they were not common. Vaccinated people have a form of the disease known as variola sine eruptionea high fever after the incubation period without skin rash. Vaccinated people had confirmed antibodies in the blood, but virus isolation was rare.

Signs And Symptoms Of Smallpox In Children

Symptoms usually begin after the incubation period that lasts approximately 12 days after contracting the illness. However, some people had the disease as early as seven days or as late as 19 days after the exposure. The following symptoms were seen in the initial days of illness (4).

  • High fever
  • Headache
  • Fatigue
  • Backache
  • Vomiting (in some cases)

The skin rash appeared after two to three days of initial symptoms. A flat red rash beginning from the throat, mouth, face, and upper arms and spreading to other parts of the body was the initial sign of smallpox infection (4).

Flat red spots became firm and raised with pus in two to three weeks followed by scab (dark, rough crusts) formation. Scabs fell off three to four weeks after the rash and pitted scars were left on the skin (4).

Note: Some may mistake chickenpox for smallpox. These are two different viral illnesses caused by different viruses. You may notice vesicle formation on the face and trunk, and these blisters may crust within 24 hours (5). Seek immediate medical care if you suspect chickenpox in your child.

How Was Smallpox Spread?

Smallpox was a contagious disease that spread or transmitted from one infected person to another. The disease transmitted in the following ways (6).

  • Cough
  • Sneeze
  • From the air, while breathing
  • Contact with scabs
  • Contact with fluid from blisters
  • Personal items
  • Bedding

The spread of smallpox was high during the first week after the skin rash appeared. Although the infected person became less contagious after the first week of rash, they were contagious until all scabs fell off from the skin.

A person with smallpox infection could infect many people through air or contact, so scientists believe that smallpox could possibly be used for bioterrorism.

Note: If there is an outbreak of smallpox, and you are concerned about the symptoms or signs, call the local healthcare center immediately, and do not go to hospitals or anywhere to avoid infecting other people.

Risk And Complications Of Smallpox In Children

The infection rate of smallpox was high among children aged zero to 19 years. However, the death rate was high among adults over 45 years of age. Pregnant women and people with impaired immune systems had a high risk of severe illness, whereas most healthy individuals survived the disease (7).

On average, three out of ten infected people died due to smallpox infection, and survivors had permanent scars on the face and body (8). A few survivors had blindness due to ocular complications, such as keratitis and corneal ulcers.

Diagnosis Of Smallpox In Children

Visual examination, symptoms, and any history of exposure was enough to confirm the diagnosis of smallpox.

Presently, if there is a single case of suspected smallpox infection, the diagnosis will be confirmed based on the blood test and skin test. A confirmed diagnosis of smallpox is a global health emergency, and quick action plans for isolation and vaccination would be required.

Treatment For Children With Smallpox

There is no cure for smallpox disease. Taking medications to relieve symptoms such as pain and fever, and maintaining adequate hydration are the suggested treatments for managing smallpox patients (9).

As of now, supportive care and vaccination within two to three days of exposure are the treatment options to reduce the severity of the illness. Antiviral therapy, such as the use of tecovirimat (TPOXX), is shown to be effective in animal models. However, the effectiveness of these drugs on humans is not proven (9).

Isolation of patients, until they are no longer contagious, is mandatory for infection control. If you suspect smallpox disease in your child or other family members, contact the local healthcare center immediately to prevent the spread of illness and begin immediate treatment.

Can Smallpox Infection Be Prevented?

Immediate isolation of patients and exposed people could help reduce the spread of the smallpox virus. The best way to prevent smallpox disease is the smallpox vaccine. One shot of the smallpox vaccine protects a person for three to five years, and the second shot can be given to extend the protection period (6).

Smallpox vaccine can be effective in preventing the disease or reducing the severity of illness when given within three days of exposure. However, past data show that it was effective even after four to seven days of exposure (6).

A small bump or papule forms at the site of injection within three to five days of vaccination. This papule becomes a pus-filled blister and the scab forms in 14 days. People can be advised to cover the vaccine site until the scab falls off, which usually happens around 21 days after vaccination (10).

How Was The Smallpox Vaccine Developed?

Edward Jenner first introduced the smallpox vaccine in 1796. Jenner’s observations that milkmaids who had cowpox in the past were not affected with smallpox showed that vaccinia virus could protect humans from the variola virus (11).

Once infected, a person won’t be infected again from smallpox since our immune system develops antibodies against the virus. This is also achieved by vaccination, which is getting immunity without being sick. If one person is infected, all the contacts are vaccinated to prevent infection. This method of immunization is called ring vaccination, which played a significant role in eradicating the deadly smallpox virus from the world.

The World Health Organization has smallpox vaccine emergency stockpiles that can be distributed in the event of an outbreak to control the infection. Regular evaluations are done on the vaccine stock to ensure the potency for emergency use (12).

Since the eradication of smallpox, routine smallpox immunization has no longer been recommended for the general population. These days, smallpox immunization is limited to laboratory workers handling the vaccinia virus (VACV), smallpox response team members, and some military personnel.


1.  Stefan Riedel; Edward Jenner and the history of smallpox and vaccination; Proceedings (Baylor University. Medical Center) (2005).
2. Bioterrorism; The Centers for Disease Control and Prevention
3. Smallpox; The U. S Food and Drug Administration
4. Smallpox; Signs and Symptoms; The Centers for Disease Control and Prevention
5. Differences Between Chickenpox and Smallpox; Microbiology info
6. Smallpox; C.S. Mott Children’s Hospital
7. Planning for smallpox outbreak must consider immunosuppression; Sciencedaily
8. History of Smallpox;  The Centers for Disease Control and Prevention
9. Smallpox; Treatment; The Centers for Disease Control and Prevention
10. Typical Smallpox Vaccine Reaction; C.S. Mott Children’s Hospital
11. a href=””>Emergencies preparedness, response; Frequently asked questions and answers on smallpox; The World Health Organization
12. Emergencies preparedness, response; Smallpox vaccines; The World Health Organization

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