Smallpox Vaccine (Injection)

Smallpox vaccine is an active immunizing agent, prompting the immune system to produce antibodies to attack an infectious and deathly virus.


Smallpox vaccine contains a live virus call vaccinia - it's a look-alike virus to the real smallpox variola virus. As an immunization agent, the vaccine alerts the immune system of an infectious presence triggering a natural defense response to produce the antibodies needed to attack and prevent the virus from establishing itself.

Although the disease has been eliminated throughout the world, in some instances, health professionals still administer the vaccine as a health precaution. If you work in an environment where the variola virus or similar viruses are stored - you may need a vaccine. Because there is no known cure for smallpox, the vaccine needs to be administered within three to four days of contact to help prevent the disease from spreading.

A smallpox vaccine is given with a two-pronged needle dipped into the vaccine solution. Healthcare providers puncture the upper arm skin several times, allowing the solution to enter the body. The procedure leaves a mark with some blood as the needles break the skin. A scab forms and falls off after a few weeks with a small scar. Discard the scab in a separate trash container away from the household trash and out of reach of other people - it may be contaminated.

In most cases, individuals surviving the infection of smallpox develop a lifelong immunity to the disease.

Conditions Treated

Type of Medicine

  • Active immunizing agent

Side Effects

Smallpox is the only infectious disease eradicated worldwide by a vaccine. First time recipients experience stronger side effects compared to those being re-vaccinated. Individuals working in high risk or exposure environments may need a booster dose every three years for protection against smallpox.

This vaccine is the only known treatment for smallpox. Although the disease is under control, in the event of a breakout, the vaccine has been stored for use against the disease. The vaccine can protect you from getting sick, before contact. If you are exposed and get a vaccine within three days - the vaccine may prevent you from getting the disease. If you become ill, the side effects will be far less severe than an unvaccinated person. Getting the vaccine within four to seven days after exposure still offers some protection, although you may get the disease.

Tell your doctor if you have been vaccinated before allowing further treatment. Side effects are common, serious and sometimes fatal. The most serious effects occur in first timers, but precautions are necessary for everyone because the vaccine contains a live vaccinia virus that can spread throughout the body.

  • Re-vaccination rarely cause complications
  • Fetal risks increase during pregnancy

Individuals with weak immune systems or existing skin conditions like eczema are more susceptible to these infections and the side effects listed.

These side effects are most common and the severity depends on the individual's health condition, age, and term of exposure. This disease is fatal and the side effects will weaken the body. If you experience any of these effects, contact the doctor.

  • Chills
  • Pain
  • Sensitive lymph glands
  • Swelling

Some effects are least common, but they can happen. The effects involve discomfort and pain. If any of these occur, you need to seek medical attention. There may be additional signs of other body ailments associated with the smallpox side effects, or underlying health conditions that need to be treated.

  • Anxiety
  • Diarrhea
  • Drowsiness
  • Fatigue
  • Fast heartbeat
  • Fever and chills
  • Hallucinations
  • Headache
  • Insomnia
  • Irritability
  • Itching
  • Muscle pain
  • Sores, ulcers
  • Stiff neck
  • Vision changes
  • Vomiting

These effects are serious - most individuals do not experience these side effects - if you notice these symptoms, contact the doctor. If you are taking medications for these conditions, you will experience a reaction between the two drugs. In any case, it's in your best interest to talk with the health professionals before theses complications development into harmful or fatal illnesses.

  • Chest pain
  • Confusion
  • Convulsions
  • Fainting
  • Trouble breathing

Health precautions are extremely important if you are being treated or vaccinated for smallpox. Only humans can transmit and catch smallpox. The vaccinia virus is contagious - the infection is transmitted by touching the injection site, then touching another part of your body or another person.

Be sure to wash your hands with soap and water after coming in contact with the virus, the vaccination site or sores.


The dose of this vaccine is different since it's given by using a special bifurcated (two-pronged) needle versus a single hypodermic needle. The bifurcated needle is dipped into the vaccine solution, pricking the skin several times to allow the solution to enter the skin punctures.

It's given in single doses. Sometimes the doctor will prescribe a booster schedule. After the injection, the presence of a vaccination sore on the skin site confirms the effectiveness of the vaccine. If the sore does not appear within 5 days after vaccination, contact the doctor - you may need to be re-vaccinated.

Today, these are prevention routines. Contact your doctor in all situations before taking an injection of this medication. Elderly individuals and children up to the age of 18 years may experience serious reactions to this medicine.

  • Adult Dose - 1 drop
  • Geriatric Dose - 1 drop
  • Pediatric Dose - 1 drop

U.S. Food and Drug Administration (FDA) listed the following information on the medicine's dosage. The postings cite the vaccine should not be administered by intradermal, subcutaneous, intramuscular or intravenous route. A medication guideline for vaccine recipients is available during the injection session with instructions of care after the vaccination. Be sure to ask for it.

  • 0.0025 milliliters (mL) equates to 1 drop

After receiving the injection, keep the site covered at all times to allow the healing process and prevent any transfer of the infection. If you share a bed, cover the site to avoid infecting the other person.

  • DO NOT use ointments on the sore.
  • Use a waterproof bandage to cover the site while bathing.
  • Wash your hands with soap and water after touching the area, changing bandages, handling clothing, towels or fabrics that have been exposed to the sore. The virus can live on these surfaces and infect someone else.
  • DO NOT donate blood - talk with your doctor.

If anyone in your household shows symptoms of rash, fever or aches - contact the doctor at once.

Other Medication Effects

For most, the smallpox vaccination is safe and effective and the appearances of side effects are signs that the vaccine is working. Yet in some health situations like these listed, the reactions can be toxic. Acute toxicity involves harmful effects by a single or short-term exposure. Chronic toxicity can occur when mixing multiple substances, causing long-term and more serious effects.

It's critical that you share as much information about your health with your doctor before getting an injection of the smallpox vaccine. This medicine should not be administered to individuals with these conditions.

Individuals treated for immunosuppression disorders should not be injected with this medicine.


Before getting a smallpox vaccine injection, your doctor needs to know about the medicines you are taking now, both prescription and nonprescription. Blending the medicines may cause a severe interaction affecting the vaccine's purpose. Your doctor may suggest changing the doses of one or both medicines.

Here's a list of medications known to interact with this vaccine - the levels may be mild to fatal, depending on the individual response to treatment and other existing health disorders. There may be other medicines not listed that will react - it's important for your doctor to know about your health, family history, and your current dietary regimes. Sometimes health supplements, alcohol consumption and the use of tobacco can prompt a reaction or initiate another illness.

  • Azathioprine
  • Bendamustine
  • Bortezomib
  • Bosutinib
  • Carboplatin
  • Carmustine
  • Chlorambucil
  • Cisplatin
  • Cladribine
  • Cyclosporine
  • Cytarabine
  • Docetaxel
  • Doxorubicin
  • Epirubicin
  • Fluorouracil
  • Gemcitabine
  • Hydroxyurea
  • Globulin
  • Infliximab
  • Liposome
  • Mechlorethamine
  • Methotrexate
  • Mitomycin
  • Mycophenolic Acid
  • Paclitaxel
  • Pentostatin
  • Ponatinib
  • Procarbazine
  • Temozolomide
  • Teniposide
  • Topotecan
  • Tositumomab
  • Trabectedin
  • Vinblastine

Emergency versus Non-Emergency

Drug interactions pose serious health threats and risks to vaccination complications. Some are due to existing disorders; others apply to specific age groups, lacking a healthy immune system to battle the disease or the side effects. In an emergency use, the risks of smallpox disease are determined against the benefit and adverse effects of the smallpox vaccination.

DO NOT vaccinate in a non-emergency situation if these conditions exist.

  • Active eye disease
  • Treatment of topical steroids
  • Moderate to acute illness on the day of vaccination
  • Geriatric patients over the age of 65
  • Patients between one to eighteen years of age
  • Children under 12 months of age

These health conditions may affect the response of this vaccine. If you are diagnosed with these conditions, tell your doctor before getting the vaccine.


The FDA continues to watch and protect public health on vaccines. The organization acknowledges the potential of serious health problems occurring in unvaccinated individuals infected with the vaccine virus; accidentally or being in close contact with someone recently vaccinated.

Smallpox vaccine is only accessible to the public with a doctor's approval for treatment. Today, the smallpox virus does not exist because of this vaccine; the greatest prevention action taken is making sure there are sufficient amounts of the vaccine stored in the event of a large population infection.

Health Complications

Persons with heart, immune or skin problems are advised to take precautions when coming in contact with a recently vaccinated person or working in an environment with exposure to the live virus.

Known complications include:

  • Progressive vaccinia is caused by a deficient immune system. It happens when the surrounding tissues at the vaccination site become inflamed growing into a large non-healing sore.
  • Eczema vaccinatum occurs with existing skin disorders - in most cases, the condition happens by coming in contact with someone recently vaccinated or touching infected items used to cleanse or protect the vaccination site.
  • Postvaccinal encephalitis is the inflammation of the brain caused by infectious agents - the condition occurs after vaccination.

If you do experience any of these conditions or symptoms - contact your doctor at once. These effects can be life-threatening.


You should not get pregnant for at least 90 days after receiving a vaccine - it's recommended that you see your doctor before taking any form of treatment related to the smallpox vaccine. If you become pregnant within this timeframe - see your doctor immediately.

Studies show the smallpox vaccine risks are rare. There is no link of the smallpox vaccine to abortion, stillbirth or preterm birth. The congenital defects correspond to the first trimester of pregnancy - the population data for the group is limited.

  • Fetal vaccinia reports a high rate of fetal loss.
  • The vaccine may be transmitted to the infant by breastfeeding, causing complications.


Further testing conducted against the smallpox virus in laboratory studies using antiviral drugs has been effective in treating animals with a virus like smallpox. The data results show only minor side effects.


Hospital staff or professional healthcare providers are responsible for storing this medicine. In preparation for administering, the vaccine is kept at room temperature. Used medical supplies and unused portions of the vaccine are disposed of as biohazardous.


Smallpox vaccine is the only protection against this disease. Most individual receiving the vaccination experience mild reactions from a sore arm to body aches. In some situations, existing health conditions and medications interact with the vaccine, potentially causing more complications that are serious. Depending on the doctor's recommendations, the vaccine will be used, since the disease itself may have greater risks than the overall side effects of the vaccine to the infected individual.


Last Reviewed:
January 30, 2018
Last Updated:
April 05, 2018
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