There is a smallpox vaccine for monkeys. But not everyone may need it

OLDSmallpox numbers in monkeys continue to rise worldwide, raising concerns about how people can protect themselves. Until now, the World Health Organization report that in 12 countries, 92 cases have been confirmed in the recent emergence of this virus, and 28 possible cases are still under investigation. What has prompted public health officials to warn about recent outbreaks is that monkeypox is generally not common or known to circulate in these countries; it is endemic in areas of central and western Africa, but not in the European and North American countries — including the United States — that are currently seeing an increase in infections. America recorded its first case this year in Massachusetts on May 18, and officials from the U.S. Centers for Disease Control and Prevention (CDC) said at a press conference on May 23 that the agency is working with other health state agencies in New York, Florida and Utah to investigate four more potential cases. .

The good news is that there is a new, effective, and approved monkeypox vaccine. But do Americans need vaccinations?

Smallpox vaccine for monkeys

Produced by the Danish company Bavarian Nordic and named Jynneos, the vaccine uses a live version of the smallpox virus that has been engineered so that it cannot replicate in the body or cause infection, but still can activate the immune system to strengthen its defenses against both smallpox and monkeypox viruses to protect people from infection. According to studies done in vaccinated people in Africa, where the virus has been circulating for many years, two doses of the vaccine, given 28 days apart, are up to 85% effective in protecting protect people from monkeypox. It was approved by the US Food and Drug Administration (FDA) in 2019 to protect against both smallpox and smallpox in monkeys.

Americans do not regularly get vaccinated against the disease. But in November 2021, the Advisory Committee on Immunization Practices (ACIP) in the CDC looked at the question of who should get the monkeypox vaccine, since cases in the US occurred after people traveled to the United States. travel to areas in Africa where the disease is endemic. After analyzing available studies, ACIP recommends that those most at risk of exposure and infection — including scientists working in monkeypox virus research labs, who First responders can treat those occupational cases, and healthcare workers caring for infected patients — should receive the vaccine. The recommendations were accepted by CDC director Dr. Rochelle Walensky but have not been published in the agency’s publication records, MMWRthis will make the advice official.

“ACIP has done a great job of looking at all the different populations who may be at risk for occupational exposure. [to monkeypox]Brett Peterson, deputy director of the CDC’s rabies and pox virus branch. However, that was before the current clusters of cases, he said, and the committee’s members were mainly focused on how best to protect those at high occupational risk from getting infected, because there is no there is a significant risk of cases of the disease in the broader population. Given the latest developments, that recommendation may be revised before it is published to provide further guidance on the best strategy to immunize others who may be exposed if additional cases emerge. other.

Dr David Freedman, professor emeritus of infectious diseases at the University of Alabama at Birmingham, said: “Perhaps there should be a call for the CDC to publish the decisions ACIP has made regarding the use of vaccines. – Ask for smallpox for monkeys, for the recent case. and was elected president of the American Society of Tropical Medicine and Hygiene.

A possible vaccination approach

Unlike the COVID-19 vaccine, vaccinating humans against smallpox is likely not involved in a mass campaign, as monkeypox is not as contagious or contagious as SARS-CoV- 2. Monkeypox was discovered in 1958 and named after monkey populations, as part of the studies in which the virus was first identified. In recent years, human cases have been reported mainly in Central and West African countries such as Nigeria and Cameroon, with the West African virus, circulating widely in Nigeria, resulting in less severe disease. compared to the Central African version. As a poxvirus, its symptoms are similar to those of smallpox, including fever, muscle aches, and headache. Unlike smallpox, however, monkeypox also causes the lymph nodes to swell, and a few days after the initial fever, characteristic lesions begin to appear throughout the body, eventually developing into vesicles and pustules are larger before scabs form. Most people with the disease recover without treatment after two to four weeks, although antiviral therapy can be helpful, especially for people with weakened immune systems. During their May 23 press conference, CDC scientists noted that data showing the effectiveness of these antiviral treatments in human patients is still limited, and most of the data support it. Their use has all come from animal studies.

The virus can be spread in a number of ways, the most common and direct being through breaks in the skin or contact with bodily fluids. Monkeypox is also transmitted from person to person through respiratory droplets from sneezes or saliva – although infection this way is less common and more likely through direct contact with virus-filled lesions.

That’s why vaccinating monkeys against smallpox will most likely involve a version of what experts call a vaccination strategy and focus only on immunizing contacts. with infected people. “If a case is reported in the country, a public health SWAT team would go out, find the close contacts of that first case, and vaccinate only those contacts,” Freedman said. close contact, not the whole city or suburbs”. “Since monkeypox is not a virus that spreads primarily through the respiratory tract, you don’t see very large numbers of people infected. So you can do ring vaccination around known cases.”

If that approach is used, “we have enough vaccines in Strategic National Reserve Peterson said. “I am confident that there is enough vaccine to be used in this situation.” The first US contract with the Bavarian Nordic after the vaccine was approved calls for a supply of 28 million doses of the vaccine to the stockpile over a number of years. But because some of those doses were delivered around 2019, some have expired, and the terms of the agreement require the company to replace expired doses with newly manufactured ones.

Captain Jennifer McQuiston, deputy director of the Division of Pathogens and High Consequences of Pathology at the CDC, said during the press conference that there are currently around 1,000 doses of the vaccine and Bavaria Nordic is expected to ramp up production to increase production. that supply. Additionally, on May 18, the US Biomedical Advanced Research and Development Authority (BARDA), a division of the Department of Health and Human Services, called in an existing order up to 13 million additional frozen doses to add to that stockpile. According to Peterson, currently preserved versions of vaccines are made in liquid form and then frozen, giving them a shorter shelf life. Newer, lyophilized versions are first turned into a powder that makes them resistant to changes in temperature before reconstituting just before being injected. But these more shelf-stable vaccines won’t be available until 2023 and 2024.

McQuiston added that so far, officials at the Massachusetts Department of Health have identified more than 200 close contacts of the only confirmed case of monkeypox in the US — most of them healthcare workers. — and some of them have been vaccinated with doses from the national stockpile.

That stockpile also contains other, older doses of smallpox vaccine that have not been reviewed or approved by the FDA specifically for monkeypox, but can also be used to protect people against the disease later in life. , as the viruses are related, and the injections can confer immunity that can cross-react with both viruses. This vaccine, called ACAM2000, has been approved in the US, Australia and Singapore to protect against smallpox but can cause side effects including inflammation of the heart tissue and is not recommended for people have a weakened immune system. Unlike Jynneos, ACAM2000 is built around a disabled monkeypox virus that can still replicate, even though it cannot cause disease. Jynneos was developed specifically to give people with compromised immune systems an option for smallpox vaccination, but its safer profile prompted the FDA to approve it for the general public as well. shared. The vaccine’s ability to cross-react and induce immune protection against smallpox in monkeys made it doubly useful. “It’s important to know that Jynneos can be given to anyone without a detailed health check,” says Freedman.

There is not yet strong enough evidence to show where or how the recent outbreaks started, but clusters in Europe have been linked to men who have sex with men and “many reports of globally on cases of monkeypox occurring in sexual networks,” Dr. . Inger Damon, a CDC poxvirus specialist, in a declare on the agency’s website.

First genetic analysis of monkeypox virus from recent cases shows it originated in Nigeria, where one of the two common versions of the virus is endemic, and introduced to other areas around the world through infected travelers. But the researchers will continue to analyze the genetic data more deeply to understand how and how the latest clusters of cases are related.

Meanwhile, if the outbreak is significant in size and scope enough to warrant vaccination, health experts in the US are confident that enough doses of the vaccine will be distributed to people America may need them.

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