The Centers for Disease Control and Prevention have identified 21 cases of monkeypox in 11 states, and the number is expected to rise, officials reported Friday.
Genetic analysis has shown that while most cases appear to be closely related to the outbreak in Europe, two patients have versions of the virus that appear to have evolved from a case of monkeypox diagnosed in Texas last year.
Of the 17 patients for whom the agency has detailed information, all but one were men who had sex with men; 14 had traveled to other countries in the three weeks before their symptoms started. Three patients were immunocompromised.
CDC researchers have been unable to determine how a patient in an unnamed state contracted the virus. That suggests that at least in that state and possibly others, there is still community transmission, Dr. Jennifer McQuiston of the CDC to reporters.
“We really want to increase our surveillance efforts,” she said.
Health officials have identified a total of about 400 contacts from 13 patients who are also at risk of being infected with monkeypox. By identifying contacts at risk, officials can determine what resources are needed to contain the outbreak.
According to Dr. Raj Panjabi, the White House’s senior director for global health security and biodefense, health officials have so far supplied about 1,200 doses of vaccine and 100 courses of treatment to eight states.
The Monkeypox toll has soared globally this week, reaching nearly 800 cases as of Friday. The spread of the virus to at least 31 countries outside Africa, where it is endemic, has sparked alarm among scientists and public health officials.
Health officials in some countries are asking anyone who tests positive for monkey pox to self-isolate at home. The UK, which has the most cases on record, has urged patients to abstain from sex until their symptoms have resolved, then use condoms for eight weeks and limit interactions with pets and other animals that could become infected.
As the outbreak spreads, health officials around the world are rushing to gather vaccines and treatments to protect infected people and their close contacts. The options are severely limited.
The United States is one of the few countries to have stockpiled millions of doses of smallpox vaccines and drugs as a precautionary measure against return. Monkeypox is closely related to smallpox, and the vaccines and drugs are expected to be about equally effective.
In theory, there are at least two drugs and two types of vaccines available to fight a monkeypox outbreak, but most of these have been tested primarily on animals.
In a recent study of the two drugs in seven patients, only one seemed to provide any benefit, while the other caused toxic side effects.
The older of the two vaccine options was used to eradicate smallpox and can cause serious side effects, including heart problems and death. Most doses have been stored for decades and may have lost their effectiveness.
The second vaccine option, made by the Danish company Bavarian Nordic, was approved by the Food and Drug Administration in 2019 to prevent smallpox and monkeypox. In the United States, called Jynneos, it’s safer than previous vaccines, but supplies are even more limited.
Several countries, including Canada, Britain and France, have already started vaccinating close contacts of infected people, and many others have placed orders with Bavarian Nordic for additional supplies.
Several experts noted that African countries that have been battling monkey pox for years have had little to no access to these vaccines and treatments. 44 cases have been recorded so far this year in Nigeria and six other African countries where the virus is endemic, but those numbers are likely an underestimate.
The monkeypox outbreak in western countries could further limit access to vaccines and treatments in poor countries, some experts fear. “Vaccines and treatments stored elsewhere are not necessarily shared,” says Dr. Ifedayo Adetifa, Director of the Nigeria Center for Disease Control.
In Switzerland, the World Health Organization keeps about 2.4 million doses of the vaccine used to eradicate smallpox, and has a further 31 million doses stocked in five donor countries for release to countries in need.
But the WHO had previously only recommended the vaccine for people at high risk of exposure, said Tarik Jašarević, a spokesperson for the organization. Experts convened by the WHO are expected to review the guidelines in October, but “that timeline will need to be accelerated,” he said.
The WHO is also evaluating the newer Jynneos vaccine for prequalification, a step necessary for its use in many countries.
Scientific advisers to the CDC voted in November to recommend Jynneos for immunizing researchers and health professionals at risk of being exposed to smallpox or monkeypox.
The US emergency supply contains 100 million doses of an older smallpox vaccine called ACAM2000. But the vaccine contains live vaccinia virus and causes about six cases of myopericarditis — inflammation of the heart muscle — for every 1,000 people who get it.
ACAM2000 cannot be used in pregnant women, infants, or the immunocompromised – the very people who need protection against the monkeypox virus the most.
Jynneos, on the other hand, has been shown to be safe in older adults, people with HIV or AIDS, and those who have had bone marrow transplants and are therefore immunocompromised.
The US supply once contained 28 million doses of Jynneos, but those doses have all expired, according to Paul Chaplin, the chief executive of Bavarian Nordic. Federal health officials have said about 1,000 doses of Jynneos are available, but according to Dr. Chaplin has fed Bavarian Nordic thousands more in recent weeks.
In all, the United States has access to about a million doses, he said.
People infected with monkey pox can even be vaccinated a few days after exposure. They can also be treated with one of two drugs approved to treat smallpox, tecovirimat and brincidofovir, which slow the virus and give the immune system time to destroy it.
What you need to know about the Monkeypox virus?
What is monkey pox? Monkeypox is a virus endemic to parts of Central and West Africa. It is similar to smallpox, but less serious. It was discovered in 1958, after outbreaks occurred in monkeys kept for research, according to the Centers for Disease Control and Prevention.
The FDA has approved an oral form of tecovirimat, also called Tpoxx, to treat smallpox in adults and children who weigh at least 13 kilograms, or 28.6 pounds, although the drug has never been tested in children.
The drug, made by New York-based company Siga Technologies, is taken twice daily for 14 days, and in safety studies, it appeared to have no serious side effects other than stomach symptoms.
US stock contains 1.7 million courses of tecovirimat† On May 12, before the monkeypox outbreak hit, the Department of Defense purchased an additional $7.5 million worth of drug courses, about half of which would be delivered this year.
“A significant number of countries” have requested courses with the drug since the outbreak began, said Dennis Hruby, chief scientist at Siga. By the end of June, the company expects to be able to distribute up to 190,000 courses, he said.
The FDA worked with Siga to develop an intravenous formulation and approved it on May 19. This version can be used in patients who cannot take the oral medication because of blisters in their mouth.
Health Canada, the country’s national health department, approved tecovirimat in 2020 and, according to Dr. Hruby bought doses worth $13 million. The European Medicines Agency also approved the drug in January to treat all orthopox viruses — the viral family that includes both smallpox and monkey pox — but was still negotiating with the company when the outbreak broke out.
Tecovirimat and brincidofovir are both approved under the FDA’s Animal Rule, which allows the agency to rely on rodent or monkey data when testing a drug in humans is unethical.
The second drug, brincidofovir, is made by Chimerix and appears to have more side effects, including a risk of death, prompting the agency to issue a so-called black box warning — the strictest warning — against taking the drug.
In the recent study of both drugs, brincidofovir “was not observed to have a convincing clinical benefit,” researchers reported. But the study was too small and the treatment regimens offered to patients were too varied to draw any conclusions about the drugs’ efficacy, said David Evans, a virologist at the University of Alberta who consults for Chimerix.
Those who cannot safely use tecovirimat or brincidofovir — people who are immunocompromised, for example — can receive an immune therapy called vaccinia immunoglobulin, but there are only limited amounts.
The United States is helping to develop a cocktail of monoclonal antibodies that can block the monkeypox virus. Several vaccines are also in early development, including some that rely on horse pox.
In the long run, it may make sense for the United States to stockpile enough vaccines and drugs to protect the entire population — including those who may have been vaccinated against smallpox in childhood, said Dr. Seth Lederman, chief executive of Tonix, which is developing a horse pox vaccine.
Multiple studies suggest that people who have been vaccinated against smallpox may be protected against serious illness, if not infection. But developing even a few lesions would be enough to spread the virus to others, Dr. Lederman on.
“In the case of something like monkey pox, I think the goal would be that people don’t get lesions,” he added.
Tonix’s vaccine will not be available for use during the current outbreak. “Our approach will be to go slow and steady,” he said. “These problems are not going away.”