Chloe Ramirez
Smallpox is a serious and highly contagious infectious disease caused by the variola virus. It is believed to have killed more people than any other infectious disease, with around 300 million deaths. However, it was successfully eradicated through vaccination and public health procedures to track and contain the disease. The last case of smallpox occurred in Somalia in 1977, and the World Health Organization (WHO) declared it eradicated in 1980. Today, smallpox vaccines are not recommended for the general public, but they are available in the event of an outbreak. While the smallpox vaccine does not provide lifetime protection, several studies have suggested that it can provide protection against lethal smallpox for longer than five years, and that multiple vaccinations may not be necessary. For instance, a study in Liverpool between 1902 and 1903 found that the smallpox vaccine protected against the disease even 50 years after vaccination.
| Characteristics | Values |
|---|---|
| How long does a smallpox vaccine last? | Smallpox vaccination can protect you from smallpox for about 3 to 5 years. After that time, its ability to protect you decreases. |
| Who should get the smallpox vaccine? | Currently, smallpox vaccines are not recommended for the general public because smallpox has been eradicated. The only people who receive the smallpox vaccine today are laboratory workers who work with certain viruses and some people in the military. |
| How effective is the smallpox vaccine? | Historically, the vaccine has been effective in preventing smallpox infection in 95% of those vaccinated. In a study in Liverpool, the fatality rate for 30- to 49-year-olds was 3.7% in the vaccinated group and 54% in the unvaccinated group. |
| How does the smallpox vaccine work? | The smallpox vaccine is made from a virus called vaccinia, which is a poxvirus similar to smallpox but less harmful. The vaccine causes an immune reaction in your skin that leaves a small scar. |
| Why was the smallpox vaccine so successful? | Smallpox is a highly contagious virus that was almost eradicated through vaccination. It is a stable virus with a low mutation rate, which gave scientists a big advantage in creating a vaccine that would last a long time. |
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What You'll Learn
- Smallpox vaccines are no longer available to the general public
- The smallpox vaccine is made from a virus called vaccinia
- The World Health Organization (WHO) recommended revaccination every five to ten years
- A smallpox vaccine can prevent a fatal outcome, even if it doesn't prevent infection
- The smallpox vaccine leaves a scar on the upper arm
Smallpox vaccines are no longer available to the general public
Smallpox is a serious infectious disease caused by the variola virus. Vaccination led to the eradication of smallpox, with the last case seen in 1977. Routine smallpox vaccination among the American public stopped in 1972 after the disease was eradicated in the United States.
Historically, the vaccine has been effective in preventing smallpox infection in 95% of those vaccinated. In addition, the vaccine was proven to prevent or substantially lessen infection when given within a few days after a person was exposed to the variola virus. The World Health Organization (WHO) recommended that international travelers to non-endemic countries should be revaccinated every five to ten years and travelers to endemic countries should be revaccinated every three years. Lab workers in diagnostic facilities and others more likely to be exposed to the smallpox virus were advised to be vaccinated annually.
Several cross-sectional epidemiological studies have suggested that smallpox vaccination provided recipients with protection against lethal smallpox for longer periods than previously thought, and that multiple inoculations might not be necessary.
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The smallpox vaccine is made from a virus called vaccinia
The vaccinia virus is administered through multiple punctures of the skin with a bifurcated needle. This causes a localized infection or "pock" to form. A successful vaccination will result in a red, itchy sore spot at the site of vaccination within 3-4 days. A blister then develops and dries up, forming a scab that falls off in the third week, leaving a small scar.
There are two licensed smallpox vaccines in the United States: ACAM2000 and APSV. ACAM2000 is a second-generation vaccine derived from a clone of the first-generation Dryvax vaccine. It is manufactured by Emergent Product Development Gaithersburg, Inc. and was approved by the FDA in 2008. The vaccine is made from a live vaccinia virus and is administered in the same way as the first-generation vaccines.
First and second-generation vaccines can cause serious side effects in a small percentage of recipients, including death in 1-10 people per million vaccinations. The vaccinia virus can also spread from the vaccination site to other parts of the body or to other people, so it is important to care for the vaccination site attentively.
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The World Health Organization (WHO) recommended revaccination every five to ten years
Smallpox was the first human infection to be successfully eradicated through vaccination and public health procedures to track and contain the disease. The last case of natural smallpox occurred in Somalia in 1977, and the World Health Organization (WHO) declared it to be eradicated in 1980. Since the virus no longer exists in nature, smallpox vaccines are not available to the general public.
However, prior to the eradication of smallpox, the WHO recommended revaccination every five to ten years for international travellers to non-endemic countries. For travellers to endemic countries, the recommended interval was shorter, at every three years. Lab workers in diagnostic facilities and others more likely to be exposed to the smallpox virus were advised to be vaccinated annually.
The basis for the WHO's guidelines was that a history of vaccination within five years was known to offer good protection. In contrast, data beyond ten years was challenging to interpret, justifying a conservative estimate of smallpox immunity. While vaccination 40 years ago may not confer protection against smallpox infection, it may still offer some defence against a fatal outcome.
In summary, while smallpox has been eradicated and the vaccine is not widely available, the historical recommendations of the WHO regarding revaccination every five to ten years are worth noting. These guidelines were based on the understanding of smallpox immunity at the time and the recognition that vaccination could provide protection against fatal outcomes, even if not against infection.
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A smallpox vaccine can prevent a fatal outcome, even if it doesn't prevent infection
Smallpox was the first human infection to be successfully eradicated through vaccination and public health procedures to track and contain the disease. The last case of natural smallpox occurred in Somalia in 1977, and the World Health Organization (WHO) declared it eradicated in 1980. This means that the virus no longer exists in nature, and the general population is no longer vaccinated against it.
However, the question of whether immunity to smallpox lasts a lifetime is complex. While the smallpox vaccine can prevent infection, its effectiveness wanes over time. It is generally recommended that individuals with repeated exposure to smallpox, such as international travelers to endemic countries, should be revaccinated every 5 to 10 years. This is because the protection offered by the vaccine decreases after 3 to 5 years, and data beyond 10 years is challenging to interpret.
Several studies suggest that a single smallpox vaccination can provide long-term protection and even prevent a fatal outcome, even if it doesn't prevent infection. A study in Liverpool, England, in the early 1900s found that the fatality rate for vaccinated individuals aged 30 to 49 years was 3.7%, compared to 54% in the unvaccinated group. For those over 50, the fatality rate was 5.5% in the vaccinated group and 50% in the unvaccinated group. This indicates that the smallpox vaccine can provide protection against fatal outcomes even 50 years after vaccination.
Additionally, cross-sectional epidemiological studies and longitudinal data support the argument that a single vaccination elicits functional antibodies that remain stable over a lifetime. These antibodies may decrease in number over time, but they can still provide some level of protection against the disease.
While the smallpox vaccine may not confer complete protection against infection decades after vaccination, it can still help prevent a fatal outcome. This is because the body retains a "memory" of the virus, allowing it to quickly deploy new antibodies and activate "killer" T cells to fight the infection. Therefore, while the smallpox vaccine may not last a lifetime in terms of complete immunity, it can still provide a level of protection that reduces the severity of the disease and prevents fatal outcomes.
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The smallpox vaccine leaves a scar on the upper arm
The smallpox vaccine is no longer routinely administered to the general public, as smallpox has been eradicated. The last case of natural smallpox occurred in Somalia in 1977, and the World Health Organization (WHO) declared it to be eradicated in 1980.
Smallpox vaccination used to be quite common, and many people have a resulting scar on their upper arm. The scar is a sign that the vaccine successfully spurred an immune response in the body to protect against smallpox. The smallpox vaccine causes a minor infection in the skin, leading to a small, round scar with irregular edges that may be slightly lower than the surrounding skin.
The smallpox vaccine was first developed in the late 1700s by Edward Jenner, a family physician in southern England. He noticed that women who milked cows (milkmaids) seemed to be spared from smallpox infection. He reasoned that these women were getting infected with cowpox, a similar virus that rarely causes disease in humans, and that this infection was protecting them from smallpox. Jenner's use of cowpox to protect against smallpox was the first successful instance of a vaccine.
While smallpox vaccination is no longer routine, there are still two licensed smallpox vaccines in the United States. The vaccines are called ACAM2000 and APSV, and they are replication-competent smallpox vaccines. These vaccines are currently only administered to select groups, such as laboratory workers who handle certain viruses and some military personnel.
The length of protection conferred by the smallpox vaccine has been the subject of much study. The World Health Organization (WHO) previously recommended revaccination every five to ten years for international travelers to non-endemic countries and every three years for travelers to endemic countries. However, recent studies suggest that a single vaccination may provide protection for much longer, possibly even a lifetime.
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Frequently asked questions
Smallpox vaccines are not available to the general public because smallpox has been eradicated, and the virus no longer exists in nature. However, a study in Liverpool, England, in the early 1900s found that the smallpox vaccine protected against the disease caused by smallpox even 50 years after vaccination. Another longitudinal study found that a single vaccination elicits functional antibodies that remain stable over a lifetime.
The smallpox vaccine is currently administered to laboratory workers who work with certain viruses and some people in the military.
The smallpox vaccine is made from a virus called vaccinia, which is a poxvirus similar to smallpox but less harmful.
