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Who Is Protected Against Monkeypox?


For a world tired of battling the coronavirus, the monkeypox outbreak raises an important question: Am I at risk?

The answer is you can rest assured. Experts say in interviews that most children and adults with healthy immune systems can avoid serious illness. But there are two high-risk groups.

One covers infants under six months. But they are yet to be affected by the current outbreak. And many older adults, the group most likely to succumb to the monkeypox virus, are at least partially protected by decades of smallpox vaccination, studies show.

Vaccinated older adults may be infected but is likely to get away with only mild symptoms.

Dr Luigi Ferrucci, scientific director of the National Institute on Aging, said: “The bottom line is that even those vaccinated many decades earlier maintain very high levels of antibodies and the ability to become sterile. virus inactivation.

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

In the United States, routine vaccination for smallpox ended in 1972. The military continued the vaccination program until 1991 as a precaution against a bioterrorism attack.

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

“We cannot guarantee that a person who has been vaccinated against smallpox will still be protected from monkeypox,” said Dr. Fauci.

The monkeypox outbreak has grown with about 260 confirmed cases and scores under investigation in 21 countries. The infection begins with respiratory symptoms but develops into a separate rash, first on the mouth, then on the palms and soles, and gradually the rest of the body. The rash eventually emerges, developing into pus-filled blisters.

Each pustule contains a live virus, and a broken blister can contaminate bed linens and other items, putting close contacts at risk. Infected people should also be very careful about rubbing their eyes because Viruses can destroy vision.

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

Dr. Slifka and other experts emphasize that while monkeypox can be serious and even fatal, the current outbreak is unlikely to become a major epidemic.

“We are fortunate to have vaccines and treatments that can reduce it,” said Anne Rimoin, an epidemiologist at the University of California, Los Angeles, who has studied monkeypox in Africa. minimize all of that. “We have the ability to stop this virus.”

Smallpox in monkeys takes up to 12 days to cause symptoms, giving doctors a chance at least 5 days after vaccination and prevention. (The approach, known as post-exposure prophylaxis, is not an option for Covid patients because the coronavirus can begin to wreak havoc on the body just days after exposure.)

The monkeypox virus is not spread when there are no symptoms. Dr. Rimoin said, careful surveillance, isolation of infected people, contact tracing and isolation of contacts will stop the outbreak.

The majority of those infected are currently men under the age of 50, and many identify as gay or bisexual, which may reflect a possible origin at a Gay Pride event in the Canary Islands. . (Experts say the outbreak could easily have started among heterosexuals at a big event.)

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

There are mixed opinions about how long immunity after a smallpox vaccination lasts.

Centers for Disease Control and Prevention Proposal of boosters David Daigle, a spokesman for the agency, said in a statement the smallpox vaccine is given every three years but is only “for those at risk of occupational exposure”.

“Until we know more, we will use the vaccine that is available to people who have been in close contact with known cases and who are most at risk of exposure through work,” he said. their own, like health care workers treating monkeypox.”

The United States and some European countries have begun vaccinating close contacts of infected patients, a method known as round vaccination.

Many of the most vulnerable groups could have been protected. In one study, Dr. Slifka and his colleagues drew blood from 306 vaccinated volunteers, some of whom had been vaccinated decades earlier, including one who had been vaccinated 75 years earlier. Most of them maintained high levels of antibodies to smallpox.

In another study, Dr. Slifka and his colleagues showed that Antibodies are produced because even a dose of smallpox vaccine drops very slowly in the body, halving after about 92 years.

Dr. Ferrucci and his colleagues at the NIH, as well as other groups, have also found that antibody levels existed for decades after vaccination. Some studies have found that other branches of the immune system also slowly weaken, but antibodies are produced from Smallpox vaccination may be enough their own to protect against monkeypox.

If smallpox starts to spread, it makes sense to vaccinate anyone exposed because of the rates, said Gigi Gronvall, a biosecurity expert at the Johns Hopkins Center for Health Security. mortality is high, regardless of previous vaccinations.

“We don’t want to take the chance that someone isn’t protected,” she said.

But that’s not necessary now, she added: “This is monkeypox.”

Laboratory evidence for antibodies does not demonstrate that smallpox vaccination protects against smallpox in monkeys. But answering that question would require study participants to be intentionally infected with smallpox or a related virus, an experiment that is clearly unethical.

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

However, one way to study the effectiveness of vaccines in humans is to collect evidence during outbreaks. Dr. Slifka’s team did just that in 2003, when dozens of Americans became infected with monkeypox after coming into contact with infected prairie dogs.

The researchers flew to Milwaukee and drew blood from 28 people who had come into contact with infected prairie dogs. Of the 8 people who were previously vaccinated, 5 developed an average of 3 pus-filled blisters, compared with an average of 33 in the unvaccinated.

Three other vaccinated individuals no symptoms at all. “They didn’t even know they were infected,” Dr. Slifka said.

Again research on that outbreak found that in a family of three, the previously vaccinated father developed only two cases of smallpox in monkeys compared with 200 in the unvaccinated mother. Their unvaccinated 6-year-old daughter had about 90 wounds and was in a coma for 12 days.

Questions about the durability of vaccine protection against smallpox in monkeys are of particular significance as the number of cases of the disease worldwide has increased. Monkeypox recurred among people in Nigeria in 2017, and since then there have been around 200 confirmed and 500 suspected cases.

The Democratic Republic of the Congo has recorded 58 deaths and nearly 1,300 suspected cases since the start of this year.

People in African villages used to catch smallpox in monkeys from hunting animals but rarely infect others. Dr. Rimoin says the larger outbreaks are only recent, like the last few years, when we’ve started to see this.

The eradication of smallpox, while one of the greatest public health achievements, has left populations vulnerable to the virus and its cousins.

Declining immunity, coupled with population growth and increased proximity to wildlife, could lead to more frequent monkeypox outbreaks, Dr. Rimoin and colleagues grandma’s warning in 2010.

Unbridled outbreaks, especially in immunocompromised individuals, will give the virus more of a chance to acquire mutations that make it more resilient – in humans and animals.

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





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