According to the latest updates from the statistics site Our World in Data, there are already more than 300 confirmed cases of monkeypox since the start of the outbreak in countries where the disease is not endemic. In addition, many other cases are being investigated in 21 countries.
And in a world exhausted from fighting the coronavirus, after two years and three months of the pandemic, the new outbreak raises the inevitable questions: who is at risk? Is there any group of the population that is more protected? which?
The first response from specialists is encouraging: Most children and adults with healthy immune systems are likely to avoid serious illness. However, there are two groups that are considered high risk.
One is represented by babies under six months, who although the current outbreak has not yet registered cases in this group, it is known that their defenses are lower against all diseases. At the other extreme, many older adults, the group most likely to succumb to the monkeypox virus, have at least a percentage protection from smallpox vaccines given decades ago, studies suggest.
Thus, vaccinated older adults could become infected, but are likely to experience only mild symptoms.
“The bottom line is that even those who were vaccinated many decades ago maintain a very, very high level of antibodies and the ability to neutralize the virus,” said Luigi Ferrucci, scientific director of the National Institute on Aging. “Even if they got vaccinated 50 years ago, that protection should still be there,” he said.
Regarding the durability of the smallpox vaccine, Anthony Fauci, the top adviser on infectious diseases in the Joe Biden government, assured that it is reasonable to assume that the majority of vaccinated people are still protected, but acknowledged that “the durability of protection varies. from person to person”.
“We cannot guarantee that a person who has been vaccinated against smallpox is protected against monkeypox,” Fauci said. There are mixed opinions about the duration of immunity from a smallpox vaccine.
The Centers for Disease Control and Prevention recommends boosters of smallpox vaccines every three years, but only “for people at risk of exposure due to their occupation,” David Daigle, an agency spokesman, said in a statement.
In the United States, for example, routine smallpox immunization was discontinued in 1972. The military continued its vaccination program until 1991 as a precaution against a bioterrorist attack, according to The New York Times.
“Until we know more, we will continue to use available vaccine stockpiles for people who have had close contact with known cases and people at highest risk of exposure through their jobs, such as health professionals treating patients. with monkeypox,” Daigle said.
The United States and several European countries have begun immunizing close contacts of infected patients, a strategy called ring vaccination.
Many of the most vulnerable groups could already be protected. In one study, Mark Slifka, an immunologist at Oregon Health & Science University, and colleagues took blood samples from 306 vaccinated volunteers, some of whom had been immunized decades ago, including one who had been immunized 75 years earlier. . And they found that most maintained high levels of smallpox antibodies.
Ferrucci and his NIH colleagues, as well as other teams, also found that antibody levels persist for decades after vaccination. Some studies found that other branches of the immune system decline slowly as well, but the antibodies produced by vaccination may be enough on their own to protect against monkeypox.
Who is at risk of Monkeypox?
On the other hand, there are three population groups at higher risk of being infected with monkeypox, according to Dr. Richard Kennedy, professor of medicine and co-director of the Mayo Clinic Vaccine Research Group.
The first is made up of those people who travel to areas where the disease is endemic. According to the World Health Organization, the countries where monkeypox is endemic are Benin, Cameroon, Central African Republic, the Democratic Republic of the Congo, Gabon, Ghana (where cases were identified only in animals), Ivory Coast, Liberia, Nigeria, Sierra Leone, South Sudan, and the Republic of the Congo, where the first human case was identified in 1970.
Travel, in fact, is a key factor in outbreaks. With “very few exceptions”, according to the expert, all cases of monkeypox that had been recorded before outside of Africa were from travelers returning from that continent.
Those in close contact with these travelers and health care workers treating monkeypox patients without proper personal protective equipment are also at increased risk.
Regarding who can develop more severe disease, Kennedy noted that “immunocompromised people are likely to be infected more easily and develop more severe disease.” According to the expert, this category includes HIV-positive people, cancer patients, organ transplant recipients, and those taking immunosuppressive drugs.
Likewise, some skin conditions such as eczema and atopic dermatitis are associated with more serious infections due to the orthopoxvirus, a genus of which monkeypox is a part, but it is not yet known if this will be the case for the disease of monkeypox.
Monkeypox infection, also called monkeypox, begins orthopoxvirus with respiratory symptoms but develops into a distinctive rash, first in the mouth, then on the palms of the hands and soles of the feet, and gradually in the rest of the body. Over time, the rash grows until it becomes pus-filled blisters.
Each pustule contains a live virus, and a broken blister can contaminate bedding and other items, making close contact the riskiest.