Who is protected against monkeypox?

For a world tired of fighting coronavirus, the monkeypox outbreak raises a key question: Am I at risk?

The answer is reassuring. Healthy immunity in most children and adults can prevent serious illness, experts say in an interview. However, there are two high-risk groups.

One includes children under six months of age. But they are still not affected by the current outbreak. And many older adults, the group most likely to be infected with the monkeypox virus, are protected by at least a few decades-old smallpox vaccine, the study found.

Vaccinated adults can become infected but can only escape with mild symptoms.

“The bottom line is that even those who were vaccinated decades ago still have very high levels of antibody and virus neutralization,” said Dr. Luigi Ferruchi, scientific director at the National Institute on Aging.

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

In the United States, regular vaccinations for smallpox were discontinued in 1972. The military continued its vaccination campaign until 1991 as a precaution against biological terrorism attacks.

After the anthrax outbreak in 2001, questions were raised about the viability of the smallpox vaccine, said Dr. Anthony S. Fawcett, a top adviser on infectious diseases in the Biden administration. It was reasonable to assume that most vaccinated people were still protected, he said, “but the stability of the protection varies from person to person.”

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

The outbreak of monkeypox has included about 260 confirmed cases and more scores are under investigation in 21 countries. The infection begins with symptoms of shortness of breath but develops into a distinct rash, first on the face, then on the palms and soles of the feet, and gradually on the rest of the body. The rash eventually develops into a pus-filled blister.

Each pustule contains a live virus and a ruptured blister can contaminate bed sheets and other items, putting close acquaintances at risk. Infected people should also be very careful about rubbing their eyes as the virus can cause vision loss.

“Before the generic smallpox vaccine was developed, smallpox was the number one cause of blindness in the world,” said Mark Sliffka, an immunologist at the University of Oregon Health and Science. Infected people become infected until the pus comes out, he said.

Dr. Slyfka and other experts emphasize that although monkeypox can be deadly and even fatal, the current outbreak is unlikely to turn into a major epidemic.

“We’re lucky to have vaccines and therapeutics – all of which can alleviate this,” said Ann Remoin, an epidemiologist at the University of California, Los Angeles, who studied the monkeypox in Africa. “We have the power to stop this virus.”

It takes up to 12 days for symptoms of monkeypox to appear, and it takes at least five days for doctors to vaccinate and prevent the disease. (Post-exposure prophylaxis is not an option for covid patients because coronavirus can begin to destroy the body just a few days after exposure.)

In the absence of symptoms, the monkeypox virus does not spread. Outbreaks appear to be exacerbated during surveillance, isolation of infected people, search for contacts and segregation of contacts, Dr. Remoin said.

Most of those currently infected are men under the age of 50 and many are identified as homosexual or bisexual, which may reflect the potential source of the outbreak at a gay pride event in the Canary Islands. (Experts say that the prevalence of heterosexuality in a large event can easily start.)

No deaths have been reported. However, experts are especially concerned about close contact with children, the elderly or those with weakened immune systems for other reasons.

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

The Center for Disease Control and Prevention recommends a smallpox vaccine booster every three years but only “for those at risk of personality exposure,” said David Diegel, a spokesman for the agency, in a statement.

“Until we know more, we will use the vaccine stock available to people who have had close contact with known cases and who are at the highest risk for exposure through their jobs, such as healthcare workers treating monkeypox patients,” he said.

The United States and several European countries have begun vaccinating infected patients through close contact, a method called ring vaccination.

Many vulnerable groups may already be protected. In one study, Dr. Slyfka and his colleagues drew blood from 306 vaccinated volunteers, some of whom were vaccinated decades ago, one of whom was vaccinated 75 years ago. Most of them maintained high levels of antibodies to smallpox.

In another study, Dr. Slyfka and his colleagues showed that antibodies produced by a single dose of the smallpox vaccine are reduced very slowly in the body, halving after about 92 years.

Dr. Feruchi of NIH and his colleagues, as well as other teams, have observed that antibody levels persist for decades after vaccination. Some studies have shown that other branches of the immune system are also slowly declining, but antibodies produced by the smallpox vaccine may be sufficient to protect themselves against monkeypox.

Gigi Gronval, a biosecurity expert at the Johns Hopkins Center for Health Security, said that if smallpox began to spread, it would make sense to vaccinate anyone infected with the high mortality rate, regardless of the previous vaccine.

“We don’t want to take advantage of the fact that someone has been left unprotected,” he said.

But it’s not necessary now, he added: “It’s a monkeypox.”

Laboratory evidence of antibodies does not prove that the smallpox vaccine can protect against monkeypox. But to answer this question, study participants must have been deliberately infected with smallpox or a related virus, a test that is clearly unethical.

For the same reason, new cocoon spring vaccines and drugs have only been tested in animals.

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

Researchers flew to Milwaukee and took the blood of 28 people who came in contact with infected prairie dogs. Of the eight people who had been vaccinated earlier, five had an average of three pus-filled blisters, and an average of 33 had not been vaccinated.

The other three vaccinators had no symptoms. “They didn’t know they were infected,” said Dr. Slyfka.

Another study of that outbreak found that in a family of three, only two monkeypox lesions developed in 200 vaccinated mothers of previously vaccinated fathers. Their unvaccinated 6-year-old girl had about 90 wounds and was in a coma for 12 days.

Questions about the sustainability of vaccine protection against monkeypox have gained special significance as the number of cases worldwide has increased. Monkeypox reappeared among the people in Nigeria in 2017 and since then there have been about 200 confirmed cases and 500 suspected cases.

Congo is a democratic republic 58 people died And about 1,300 suspected cases since the beginning of this year.

African villagers used to infect monkeys from animals while hunting but rarely infect others. “It’s very recent, for example, the last few years, when we started to see it,” said Dr. Remoin.

The eradication of smallpox, although one of the best public health successes, has put the population at risk for the virus and its cousins.

Decreased immunity, population growth, and increased proximity to wildlife can lead to frequent outbreaks of monkeypox, Dr. Remoin and colleagues warned in 2010.

Uncontrolled outbreaks, especially in immunocompromised people, will give the virus a greater chance of acquiring mutations that make it more resilient – in humans and animals.

“If the monkeypox could establish itself in a wildlife reservoir outside of Africa, the catastrophe for public health would be enormous,” said Dr Remoin. “This, I think, is a legitimate concern.”

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