Smallpox

Smallpox is a very serious and often life-threatening virus. It's highly contagious, meaning it spreads easily from one person to another. This disease can leave permanent scars on the skin and sometimes cause severe disfigurement.

For thousands of years, smallpox affected human populations. However, thanks to widespread vaccination campaigns, it was completely eliminated globally by 1980. This means smallpox no longer occurs naturally. The last naturally occurring case was reported in 1977.

Scientists have kept samples of the smallpox virus for research. Modern laboratory techniques now allow scientists to recreate the virus. This ability raises concerns about the potential for smallpox to be used as a weapon of mass destruction.

While vaccines are highly effective in preventing smallpox, routine vaccination is not typically recommended because most people are unlikely to encounter the virus naturally. If someone does get smallpox, new antiviral medications are available to treat the infection.

A picture from Bangladesh in 1974 shows smallpox sores.

Smallpox usually starts showing up 12 to 14 days after you've been exposed to the virus. However, the virus might be in your body for a period of 7 to 19 days before you notice any symptoms. This early period is called the incubation period.

After the incubation period, you'll likely experience sudden, flu-like symptoms. These include:

• High temperature (fever)
• Muscle pain
• Headache
• Extreme tiredness
• Severe back pain
• Sometimes, vomiting

A few days later, flat, red spots appear on your skin. These spots can sometimes start in your mouth and on your tongue, then spread to other parts of your body. Often, the face, arms, and legs are affected first, followed by your chest, and eventually your hands and feet.

Within a day or two, these spots change into small, fluid-filled blisters. Over time, these blisters become filled with pus. These pus-filled sores are called pustules. About 8 to 9 days after the spots first appear, scabs form. These scabs eventually fall off, leaving deep, pitted scars that can last for a long time.

Smallpox is contagious from the time the rash appears until the scabs fall off. This means you can spread the disease to others during this period.

Smallpox is a disease caused by a virus called variola. It can spread in several ways:

• Direct contact: If you're near someone with smallpox, you can catch it. This happens when an infected person coughs, sneezes, or talks, releasing tiny droplets carrying the virus. Touching their skin sores also spreads the illness.

• Indirect contact: Sometimes, the virus can travel through the air, especially inside buildings. This means someone in a different room or even a different floor could get infected. It's not a common way it spreads.

• Contaminated objects: Smallpox can live on things like clothes and bedding. Touching these contaminated items could spread the disease, but this is less likely than direct or airborne transmission.

• Possible weaponization: Using smallpox as a weapon is a very low-probability threat. However, the virus could quickly spread if released deliberately, so governments are preparing for this possibility to protect the public.

Smallpox, while often survivable, can be very serious in some cases. While many people do recover, some forms of the disease are much more dangerous and are more likely to be fatal. These dangerous forms often affect pregnant women and young children.

Even if someone does recover from smallpox, they will likely have noticeable scars, particularly on their face, arms, and legs. In some cases, the infection can also lead to blindness.

If there was a smallpox outbreak, people who had smallpox would be kept separate from others to prevent the virus from spreading. Anyone who came into contact with someone with smallpox would need to get a smallpox vaccine. A vaccine works by either preventing you from getting sick at all, or by making the illness milder if you do get it. Ideally, the vaccine should be given before or within a week of coming into contact with the virus.

Two types of smallpox vaccines are available:

• ACAM2000: This vaccine uses a weakened version of the smallpox virus. While it's effective, it can sometimes cause serious side effects, including problems with the heart or brain. Because of these risks, it's not given to everyone. Unless there's a major smallpox outbreak, the risks of getting the ACAM2000 vaccine usually outweigh the benefits for most people.

• Jynneos: This vaccine uses a different, even weaker version of the virus and is generally considered safer than ACAM2000. It's a better option for people with weakened immune systems or skin conditions that might make ACAM2000 risky.

Smallpox vaccines can also protect against similar viruses, like monkeypox (also known as mpox) and cowpox.

If you received the smallpox vaccine as a child, you likely have some protection against smallpox. This immunity, either full or partial, might last for up to 10 years, and potentially 20 years with booster shots. If a smallpox outbreak occurred and you were exposed, even if you were vaccinated as a child, you might still be given a new vaccination.

If smallpox appeared again today, many doctors might not immediately know it's smallpox in the early stages. This could allow the disease to spread quickly.

Even a single case of smallpox would be a serious public health problem. The Centers for Disease Control and Prevention (CDC) has special labs equipped to examine samples of body tissue to identify smallpox. These tests are very accurate and can definitively confirm whether someone has the virus. This quick and precise diagnosis is crucial for containing an outbreak.