Who Is Protected Against Monkeypox?

For a world weary of fighting the coronavirus, the epidemic raises an important question: Am I at risk?

The answer is reassuring. Most children and adults with healthy immune systems are likely to avoid serious illness, experts said in interviews. But there are two high-risk groups.

One includes infants younger than six months. However, they have not yet been affected by the current epidemic. And research shows that many older adults, the group most likely to succumb to the monkeypox virus, are at least somewhat by decades of smallpox vaccines.

Vaccinated older adults can become infected but they are likely to escape with only mild symptoms.

Scientific director of the National Institute on Aging, Dr. “As a result, even those who were vaccinated decades ago retain very, very high levels of antibodies and the ability to neutralize the virus,” said Luigi Ferrucci.

“Even if they were vaccinated 50 years ago, that protection should still be there,” he said.

Routine immunization for smallpox in the United States ended in 1972. The military maintained the vaccine program until 1991 as a precaution against a bioterrorism attack.

The Biden administration’s lead adviser on infectious diseases, Dr. Anthony S. Fauci said questions about the durability of the smallpox vaccine arose after an anthrax attack in 2001. It’s reasonable to assume that most vaccinated people are still protected, he said, “but the durability of protection varies from person to person.”

Dr. “We cannot guarantee that a person vaccinated against smallpox will still be protected against monkey disease,” Fauci said.

The monkeypox epidemic has grown to include approximately 260 confirmed cases in 21 countries and scores under further scrutiny. The infection begins with respiratory symptoms, but develops into a distinctive rash first on the mouth, then on the palms and soles, and gradually over the rest of the body. The rash eventually rises and turns into pus-filled blisters.

Each pustule contains live virus, and a ruptured blister can contaminate bed linens and other objects, risking close contact. Infected people should also be very careful when rubbing their eyes because virus can distort vision.

“Before Jenner developed the smallpox vaccine, smallpox was the number one cause of blindness in the world,” said Mark Slifka, an immunologist at Oregon Health and Science University. Infected people are contagious until the pustules crust over and fall off, he said.

Dr. Slifka and other experts stressed that while monkeypox can be serious and even deadly, it is unlikely that the current outbreak will develop into a major epidemic.

“We’re lucky to have vaccines and therapeutics — things that can alleviate all of that,” said epidemiologist Anne Rimoin of the University of California, Los Angeles, who studies monkeypox in Africa. “We have the ability to stop this virus.”

It takes up to 12 days for Monkeypox to cause symptoms, giving doctors at least a five-day window after exposure to the vaccine and preventing disease. (The approach called post-exposure prophylaxis is not an option for Covid patients, as the coronavirus can begin to wreak havoc on the body just days after exposure.)

Monkeypox virus does not spread in the absence of symptoms. Dr. Rimoin said careful surveillance, isolation of infected people, contact tracing and quarantine of contacts should contain the outbreak.

The majority of those currently infected are men under the age of 50, with many identifying as gay or bisexual, which may reflect the possible origins of the outbreak at a Gay Pride event in the Canary Islands. (Experts said the epidemic could have easily started among heterosexual people at a large event.)

No deaths were reported. But experts are particularly concerned about close contacts with children, the elderly, or those with weakened immune systems for other reasons.

There are conflicting opinions about how long immunity from smallpox vaccine lasts.

Centers for Disease Control and Prevention recommends boosters Smallpox vaccination every three years, but only “for people at risk for occupational exposure,” the agency’s spokesman, David Daigle, said in a statement.

“Until we know more, we will use existing stocks of vaccines for people at highest risk of exposure through their jobs, such as people in close contact with known cases and healthcare workers treating monkeypox patients,” he said.

The United States and several European countries have begun to vaccinate close contacts of infected patients in an approach called ring vaccination.

Many of the most vulnerable groups may already be protected. In one study, Dr. Slifka and colleagues drew blood. 306 vaccinated volunteersSome were vaccinated decades ago, including those vaccinated 75 years ago. Most had high levels of antibodies to smallpox.

In another study, Dr. Slifka and colleagues showed that: antibodies produced Even a single dose of the smallpox vaccine decreases very slowly in the body, halving after about 92 years.

Dr. Ferrucci and his colleagues at the NIH, as well as other teams, continue for decades after vaccination. Some studies have found that other branches of the immune system also gradually decrease, but the antibodies produced from them smallpox vaccine may be sufficient on their own to protect against monkey disease.

Gigi Gronvall, a biosecurity expert at the Johns Hopkins Center for Health Security, said that if smallpox were to begin to spread, it would make sense to vaccinate everyone exposed regardless of the previous vaccine, due to the high mortality rate.

“We don’t want to risk someone being unprotected,” he said.

But that’s not necessary now, he added: “This is monkey flower.”

Laboratory evidence of antibodies does not prove that smallpox vaccine can protect against monkey disease. But answering this question would require study participants to be deliberately infected with smallpox or a related virus, which is clearly an unethical experiment.

For the same reason, newer smallpox vaccines and drugs have only been tested on animals.

Still, one way to study the vaccine’s effectiveness in humans is to gather evidence during an outbreak. Dr. Slifka’s team did just that in 2003 when dozens of Americans were infected with monkeypox after exposure to infected prairie dogs.

The researchers flew to Milwaukee and drew blood from 28 people exposed to infected prairie dogs. Five of the eight previously vaccinated people developed an average of three pus-filled blisters, compared to an average of 33 in those who were not vaccinated.

Three other vaccinated individuals had no symptoms none. Dr. “They didn’t even know they were infected,” Slifka said.

Another examining this epidemic He found that in a family of three, the previously vaccinated father developed only two monkeypox lesions compared to 200 in the unvaccinated mother. Their 6-year-old unvaccinated daughter had approximately 90 lesions and was in a coma for 12 days.

Questions about the durability of vaccine protection against monkeypox have gained particular importance as the number of cases worldwide has increased. Monkeypox re-emerged among people in Nigeria in 2017 and has since had around 200 confirmed cases and 500 suspected cases.

There is the Democratic Republic of the Congo 58 deaths recorded and nearly 1,300 suspected cases since the beginning of this year.

People in African villages caught monkeypox from animals while hunting, but rarely infected others. Dr. “We’ve only started to see this more recently, for example in the last few years,” Rimoin said of larger outbreaks.

While eradicating smallpox has been one of the greatest achievements in public health, it has left populations vulnerable to the virus and its cousins.

Dr. Decreased immunity, coupled with population growth and increased proximity to wild animals, could result in more frequent outbreaks of monkeypox, Rimoin and colleagues said. warned in 2010.

Uncontrolled epidemics, especially among immunocompromised people, will give the virus an opportunity to acquire mutations in humans and animals that make it more resistant.

Dr. “If the monkeypox were to settle in a wildlife reservoir outside of Africa, the decline in public health would be enormous,” said Rimoin. “I think that’s a legitimate concern.”

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