The Centers for Disease Control and Prevention has identified 21 cases of monkeypox in 11 states and is expected to increase, officials said Friday.
Genetic analysis has revealed that while most cases appear to be closely linked to the outbreak in Europe, two patients have versions of the virus that appear to have evolved from a case of monkeypox identified 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 traveled to other countries in the three weeks before their symptoms appeared. Three patients have weakened immunity.
CDC researchers have not been able to identify how an unnamed patient acquired the virus. This suggests that there is ongoing transmission to the community, at least in this state and probably in others, Dr. Jennifer McQueston of the CDC told reporters.
“We really want to increase our monitoring efforts,” she said.
Health officials have identified a total of about 400 contacts of 13 patients who are also at risk of contracting monkeypox. Identifying contacts at risk will help employees determine what resources are needed to control the outbreak.
So far, health officials have delivered about 1,200 doses of vaccine and 100 courses of treatment in eight states, according to Dr. Raj Punjabi, senior director of the White House for Global Health Security and Biosecurity.
The number of monkeypox worldwide has risen sharply this week to nearly 800 cases as of Friday. The spread of the virus to at least 31 countries outside Africa, where it is endemic, has caused concern among scientists and public health officials.
Health officials in some countries are asking anyone who has tested positive for monkeypox to isolate themselves at home. The UK, which has recorded the highest number of cases, has called on patients to abstain from sex until their symptoms disappear, to use condoms for eight weeks thereafter and to limit contact with pets and other animals that can become infected. .
As the epidemic grows, health professionals around the world are rushing to collect vaccines and treatments to protect infected people and their close contacts. The options are very limited.
The United States is one of the few countries to have accumulated millions of doses of smallpox vaccines and drugs as a precaution against its return. Monkeypox is closely related to smallpox, and vaccines and drugs are expected to be approximately as effective.
In theory, there are at least two drugs and two types of vaccines to fight the outbreak of monkeypox, but most of them have been tested primarily on animals.
In a recent study of both drugs in seven patients, only one appeared to offer any benefit, while the other caused toxic side effects.
The older of the two vaccine options has been used to kill smallpox and can cause severe side effects, including heart problems and death. Most doses have been stored for decades and may have lost their effectiveness.
The second vaccine option, developed by the Danish company Bavarian Nordic, was approved by the Food and Drug Administration in 2019 to prevent smallpox and monkeypox. Named Jynneos in the United States, it is safer than previous vaccines, but supplies are even more limited.
Several countries, including Canada, the United Kingdom and France, have already started vaccinating close contacts of infected people, and many others have ordered Bavarian Nordic for additional supplies.
Several experts noted that African countries that have been battling monkeypox for years have had little or no access to these vaccines and treatments. So far this year, 44 cases have been reported in Nigeria and six other African countries where the virus is endemic, but those numbers are likely to be underestimated.
Outbreaks of monkeypox 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,” said Dr. Ifedayo Adetifa, director of the Nigerian Centers for Disease Control.
In Switzerland, the World Health Organization maintains about 2.4 million doses of the vaccine used to eradicate smallpox, and has amassed another 31 million doses in five donor countries that can be released to countries in need.
But previously, the WHO recommended the vaccine only for people at high risk of exposure, said Tarik Jasarevic, a spokesman for the organization. Experts convened by the WHO were due to revise the guidelines in October, but “this deadline will have to be speeded up,” he said.
The WHO is also evaluating the newer Jynneos vaccine for pre-qualification, a step needed for its use in many countries.
The CDC’s scientific advisers voted in November to recommend Jynneos to immunize researchers and healthcare professionals who are at risk for exposure to smallpox or monkeypox.
The US emergency stockpile 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 receive it.
ACAM2000 should not be used in pregnant women, infants or those with weakened immune systems – the people who need protection most from the monkeypox virus.
Jynneos, in contrast, has been shown to be safe in the elderly, people living with HIV or AIDS, and those who have had a bone marrow transplant and are therefore immunocompromised.
The U.S. stockpile once contained 28 million doses of Jynneos, but all of those doses have expired, according to Paul Chaplin, CEO of Bavarian Nordic. Federal health officials said there were about 1,000 doses of Jynneos, but Bavarian Nordic has delivered thousands more in recent weeks, according to Dr. Chaplin.
In total, the United States has access to about one million doses, he said.
People infected with smallpox can be vaccinated even a few days after exposure. They can also be treated with one of the two drugs approved for the treatment of smallpox, tecovirimate and brincidofovir, which slow down the virus and give the immune system time to destroy it.
The FDA has approved an oral form of tecovirimate, also called Tpoxx, for the treatment of smallpox in adults and children weighing at least 13 kilograms or 28.6 pounds, although the drug has never been tested in children.
What you need to know about the monkeypox virus
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What is monkeypox? Monkeypox is a virus endemic to parts of Central and West Africa. It is similar to smallpox, but less severe. It was discovered in 1958 after outbreaks in monkeys kept for testing, according to the Centers for Disease Control and Prevention.
What are the symptoms? Monkeypox creates a rash that begins with flat red spots that rise and fill with pus. Infected people may also have fever and body aches. Symptoms usually appear within six to 13 days, but it can take up to three weeks after exposure for them to appear and can last for two to four weeks. Health officials say smallpox vaccines and other treatments can be used to control the outbreak.
How contagious is it? The virus is spread through body fluids, skin contact and respiratory droplets. This does not usually lead to large outbreaks, although it has spread in unusual ways this year and among populations that have not been vulnerable in the past.
Should I be worried? The virus is more likely to spread during sexual intercourse, but the risk of transmission in other ways is low. Most people have mild symptoms and recover within weeks, but the virus can be fatal in a small percentage of cases. Studies also show that older people may have some protection against decades of smallpox vaccinations.
The drug, manufactured by New York-based Siga Technologies, is taken twice a day for 14 days, and safety tests do not appear to have any serious side effects other than stomach symptoms.
US inventories contain 1.7 million courses of tecovirimate. On May 12, before the outbreak of monkeypox, the Department of Defense provided another $ 7.5 million in drug courses, about half of which were due this year.
“A significant number of countries have requested drug courses since the beginning of the epidemic,” said Denis Hrubi, a senior scientist at Siga. The company expects to have up to 190,000 courses of treatment by the end of June, he said.
The FDA is working with Siga to develop an intravenous formulation and approved it on May 19. This version can be used in patients who are unable to take oral medications due to blisters in their mouth.
Health Canada, the country’s national health department, approved tecovirimate in 2020 and has purchased $ 13 million worth of doses, according to Dr. Hrubi. The European Medicines Agency also approved the drug in January to treat all orthopox viruses – a viral family that includes both smallpox and monkeypox – but was still in talks with the company when the outbreak broke out.
Both tecovirimate and brincidofovir are approved under the FDA Animal Policy, which allows the agency to rely on data from rodents or monkeys when it is unethical to test a drug in humans.
The second drug, brincidofovir, is manufactured by Chimerix and appears to have more side effects, including the risk of death, prompting the agency to issue a so-called black box warning – its strongest warning – about the use of the drug.
In a recent study of both drugs, brincidofovir “was not seen to provide convincing clinical benefit,” the researchers said. But the study is too small and the treatment regimens offered to patients are too diverse to draw any conclusions about the effectiveness of the drugs, said David Evans, a virologist at the University of Alberta who advises Chimerix.
Those who cannot safely take tecovirimate or brincidofovir – people with weakened immune systems, for example – may receive an immune therapy called vaccine immunoglobulin, but there are only limited amounts.
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