Frequently Asked Questions About the Monkeypox Outbreak

The Mpox (formerly known as monkeypox) outbreak in the US hit its peak in August of 2022, and has declined from causes about 400 illnesses a day to just one, but that doesn’t mean the danger is completely gone, the Centers for Disease Control and Prevention explained in a teleconference on May 18, 2023.

In May 2023, the World Health Organization (WHO) declared an end to the global health emergency.

While cases are fewer, breakouts are still happening. Between mid April 2023 and early May, experts identified an outbreak of 21 men with Mpox in the Chicago area. “All have had mild symptoms,” and none have ended up hospitalized yet, Demetre Daskalakis, MD, White House National Mpox Response Deputy Coordinator, explained during the May 18th conference. “What’s really unique about this cluster is that most of the cases are in people who’ve had one or both vaccine doses.”

Experts still emphasize that the vaccine has been highly effective at preventing infection and severe outcomes, while they investigate reasons for breakthrough infection such as waning immunity or whether the patients were immunocompromised.

Here’s what you need to know.

What Is Mpox?

Mpox is a viral disease related to smallpox, which causes pus-filled lesions on the skin along with fever, pain, chills and exhaustion.

The main difference between the two diseases is that smallpox tends to be more severe, but mpox causes your lymph nodes to swell, which doesn’t happen with smallpox.

Mpox is endemic to Africa, though small outbreaks, usually among people who have recently traveled to the continent, have happened before.

Symptoms start about one to two weeks after you’ve been exposed to the virus and last two to four weeks. Historically, the disease has been fatal in about 1% of those who are infected. So far, the current outbreak appears to be more mild than previous ones.

How Is Mpox Spread? Why Is the Virus an Issue Now?

The term “monkeypox” is a bit of a misnomer. Scientists first observed the disease in monkeys in 1958, but they now think rodents are more likely to carry the virus and transmit it to humans through bites or scratches. Between humans, the disease can spread through direct physical contact or touching surfaces or clothing that comes in contact with an infected individual’s sores. Close contact includes sexual activity, but also other types of contact like cuddling and dancing.

Early in the outbreak, the CDC stated that most cases in the United States so far have been in people who have recently traveled or been in contact with someone who recently traveled to Africa or an area with a larger outbreak. But now, the disease is spreading throughout many countries, including the U.S.

There have been previous outbreaks of mpox outside of Africa, but they’ve all been short-lived. Usually, an individual had traveled to Africa right before developing symptoms. One of the most notable outbreaks, in 2003, was caused by prairie dogs that had been stored near small mammals from Ghana. In that outbreak, 47 cases of the disease in humans were reported across six states. If a person can isolate themselves when they develop symptoms, they can avoid spreading the disease to others. The main reason scientists are concerned now is that cases are showing up in countries all over the world, all at once.

How is the 2022-2023 Mpox Outbreak Different from Previous Mpox Outbreaks?

Previous outbreaks have caused painful rashes that cover large portions of the body and often start on the face, hands and feet. “All patients in the current US monkey pox outbreak in 2022 have experienced a rash, but the lesions have been scattered or localized to a specific body site,” explained Inger Daimon, MD, PhD, director of CDC’s Division of High-Consequence Pathogens and Pathology (DHCPP) in a June 21, 2022 briefing. In several cases, those body sites have been the genitals or anus, causing the disease to appear similar to sexually transmitted infections like herpes.

Many patients in the current outbreak have experienced mild fever or body aches or sometimes even no symptoms prior to developing the rash.

Global Mpox Case Tracking Count Map

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Content source: Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of High-Consequence Pathogens and Pathology (DHCPP)

A World Health Organization (WHO) situation update from June 4, 2022, states, “The sudden and unexpected appearance of monkeypox simultaneously in several non-endemic countries suggests that there might have been undetected transmission for some unknown duration of time followed by recent amplifier events.”

US States Mpox Case Tracking Count Map

[iframe src=”https://www.cdc.gov/poxvirus/monkeypox/response/2022/us-map.html” width=”100%” height=”1500″]

Who Is at Risk?

In previous outbreaks, children have often been the main ones to contract the virus. This time around, the outbreak seems to be concentrated in adult men who report having sex with other men, though some women have also tested positive for the disease. The virus is spread by close contact, but not exclusively sexual contact, with infected individuals.

A pre-print (a study that has not been peer-reviewed) posted in May 2022 in the Democratic Republic of Congo showed that out of four pregnant women who came to the hospital with Mpox, three ended up having miscarriages. There were signs that the virus had crossed the placenta and infected the fetuses.

The CDC also states that children who are under 8 years old, people who are immunocompromised or those who have pox in areas such as the eyes, mouth, genitals or anus may be at increased risk for severe outcomes. By August 15, 2022, seven children in the U.S. had tested positive for Mpox. However, Keri Althoff, PhD, MPH, an epidemiologist at Johns Hopkins Bloomberg School of Public Health, said on Sept 8, 2022 that she anticipates seeing some outbreaks in daycare centers, elementary schools and college campuses in the Fall. She emphasizes that Mpox is not as transmissible as COVID, so the risk is not as high, but, she said, “we have to remember that kids, particularly in daycare centers, but even with some kindergarteners and first graders, there is a lot of person to person contact with those kids. So it’s just making sure that we are on the lookout, right, we’re on the lookout for signs and signals of Mpox. I definitely think we will also see it on college campuses.”

Between May and September of 2022, the CDC detected 83 cases of Mpox in children under the age of 18.

Andrew Pekosz, PhD, a virologist and co-director of Johns Hopkins Center of Excellence for Influenza Research and Response, added, also on Sept 8, 2022, that, “it’s good here to note that in Western and Central Africa where mpox has been more indigenous, there are many, many cases, if not the majority of cases, that have spread among family members, and it can be in communities. So it’s possible to spread this virus in those situations.”

On Sept 15, 2022, Daskalakis White House Mpox Response Deputy Coordinator, told media at a press conference that “our data tells us that monkey pox is not an infection that exists in isolation. It travels with HIV and other sexually transmitted infections. An MMWR [morbidity and mortality weekly report] published last week, tells us that 61% of people diagnosed with monkey pox either had HIV or an STI.”

During the Sept 15 press briefing, Walensky told reporters, “over the past several weeks, we’ve also seen the racial and ethnic makeup of this outbreak evolve.” Initially many of those diagnosed with the disease were non-hispanic white men. But over the past week, data shows 38% of cases were diagnosed in non-hispanic Black, 25% of cases were among Latino and Hispanic men, and 26% were diagnosed in white men. These trends have continued into 2023.  The racial disparities are even more pronounced among the few patients who have died from Mpox, most of whom were also infected with HIV.

Typically about 1% to 10% of people who contract Mpox end up dying from the disease, but so far the current outbreak has caused few deaths. As of May 9 2023, the CDC reported more than 30,000 confirmed cases of Mpox and 43 deaths in the US during the current outbreak.

Are There Any Treatments?

No treatments have been developed specifically for mpox, however, the FDA has permitted compassionate use of several antiviral medications if a mpox outbreak occurs. Those treatments include:

• TPOXX (tecovirimat), an antiviral pill or injection originally approved to treat smallpox in both children and adults. It blocks a protein that smallpox and mpox both need to spread from cell to cell. This treatment was approved by the FDA for smallpox through the “animal rule,” because it wouldn’t have been possible to conduct clinical trials in humans. The drug’s efficacy was tested on monkeys with mpox, and the safety was assessed in human trials. A phase 3 clinical trial is ongoing, and will include children along with people who are pregnant or breastfeeding. Since the start of the outbreak, the drug has been given to 6,932 individuals with Mpox.
• Vistide (cidofovir), an antiviral designed to treat cytomegalovirus (CMV) in patients with HIV (human immunodeficiency virus) by preventing the virus from replicating. In patients with healthy immune systems, CMV rarely causes symptoms or illness, but it can be dangerous for patients with compromised immune systems, such as those with HIV.

  

• Vaccinia immune globulin intravenous (VIGIV) are antibody infusions approved to treat complications from the smallpox vaccine, such as infections and skin conditions. They are also permitted for use during a mpox outbreak.
• Tembexa (brincidofovir) was approved by the FDA in June 2021 to treat smallpox. It is incorporated into the viral DNA to slow its replication. The CDC hopes to make it available as a mpox treatment, but it does not currently have the authorization or an available stockpile.

Researchers are working to develop new antivirals, Anthony Fauci, then director of the National Institute of Allergy and Infectious Diseases, explained in a press conference in September 2022 because it is always possible that the virus could evolve to resist TPOXX, the treatment being used most often at this point. So far, CDC researchers have found that fewer than 1% of Mpox strains can resist TPOXX.

What are the Side Effects of Medications Available to Be Used for Mpox?

Side effects of tecovirimat

The drug is generally well-tolerated, but you can experience:

• Headache
• Nausea, vomiting or diarrhea
• Pain
• Fever
• Chills
• Depression or irritability
• Abnormal heart rhythms

Warnings about Vistide, cidofovir

Cidofovir’s label carries a black box warning that the drug can cause kidney impairment, which may be fatal. It may also lead to birth defects, cancer and impaired fertility.

Other occasional side effects of cidofovir include:

• Blurry vision
• Nausea and vomiting
• Fever
• Infections
• Difficulty breathing
• Weakness and fatigue
• Headache
• Rash
• Hair loss
• Anemia
• Pain
• Chills
• Reduced white blood cell counts, which can leave you vulnerable to infections.

Warnings about vaccinia immune globulin intravenous:

Vaccinia immune globulin intravenous carries a black box warning stating that because the drug contains maltose, it can result in a number of ill effects. It can interfere with typical glucose monitoring, which can cause people to administer insulin when it’s not needed or allow life-threatening levels of low blood sugar to go overlooked. Blood sugar should be monitored using a monitor and test strips that detect glucose directly.

Other occasional side effects of vaccinia immune globulin intravenous include:

• Headache
• Nausea
• Chills
• Dizziness
• Renal dysfunction that can be fatal
• Blood clots
• Anemia
• Pain

Warnings about brincidofovir:

Brincidofovir’s label contains a warning that when the drug was tested for a disease other than smallpox in a clinical trial lasting 24 weeks, patients who took the drug were more likely to die than those who were given a placebo. This outcome didn’t happen in shorter trials for smallpox.

The drug may also cause birth defects and cancer. People who can become pregnant should use contraception for at least two months after taking their final dose. People whose partners can become pregnant should use condoms for at least four months after their last dose. Brincidofovir may also permanently impair fertility.

Other potential side effects of brincidofovir include:

• Liver damage
• Diarrhea and vomiting
• Abdominal pain

How Can I Avoid Getting Mpox?

Anyone who develops symptoms of Mpox should isolate and report their symptoms to their physician. Avoid contact with anyone in your household who may have the illness and consider wearing a face mask at home, since it’s possible that the virus could spread through respiratory droplets. The virus can incubate in your body for a week or more before causing symptoms, so if you suspect you may have been exposed, avoid contact with others even if you don’t have symptoms.

Additionally, the FDA has authorized one vaccine, Jynneos, to prevent Mpox and is also offering ACAM2000, a vaccine approved for smallpox, for those at high risk of exposure. Both vaccines contain a live virus. While ACAM2000 is capable of replicating in your body, Jynneos is not, so it won’t cause an infection in immunocompromised patients.

Patients take Jynneos in two doses, 28 days apart. They don’t get their highest level of protection until two weeks after the second dose. ACAM2000, on the other hand, is a single-dose vaccine that provides peak protection after 28 days. 

Early on it was not completely clear yet just how effective the vaccines are against the current strains as they act differently than previous forms of the virus and studies are ongoing, reported Science, emphasizing that, “there’s little doubt the vaccine can help, but that’s about all that’s certain. Exactly how well MVA protects against Mpox and for how long is not known.” Additionally, some countries are trying to stretch limited supplies by offering just a single dose rather than two and it’s not yet known how much protection that protocol offers.

In January 2023, researchers published a study showing Jynneos was about 86% effective in high-risk men. The CDC’s estimates of vaccine efficacy are lower. The agency reported in December 2022, that two doses were about 69% effective, while one does was 37% effective. However, it’s not clear how long that protection lasts, especially given that several men involved in the May 2023 outbreak in Chicago had been vaccinated. Still, none of them men required hospitalization, so the vaccine may have prevented severe outcomes.

Who Should Get a Mpox Vaccine?

“The vaccines are really limited to healthy adults,” explained Pekosz, the virologist and co-director of Johns Hopkins Center of Excellence for Influenza Research and Response on Sept 8, 2022. “There’s been very little testing of this vaccine in populations outside of healthy adults.” He says it’s unlikely that vaccination against the disease would be recommended for anyone other than healthy adults, outside of extreme circumstances.

So far, the majority of vaccine recipients in the U.S. have been men between the ages of 25 and 39 years old.

What Are the Side Effects of the Mpox Vaccines?

Side effects of ACAM2000:

• Poxvirus infection, particularly in immunocompromised patients
• Myopericarditis (inflammation and swelling of the heart muscle)
• Skin issues, such as ulcers or eczema
• Fever
• Headache
• Pain
• Rash
• Fatigue
• Spreading the infection to other unvaccinated individuals

 Side effects of Jynneos:

• Injection-site reactions, like pain and redness
• Fever
• Nausea
• Muscle pain
• Chills
• Abnormal heart rhythms

The CDC specifies that people who received the Jynneos vaccine intradermally had less pain after. However, they did experience more swelling, redness, itchiness, and skin thickening which can last 2-3 weeks. This reaction is common, and can look like a single red bump around the injection site. You can ask to get the vaccine injected into the fat layer on the back of your upper arm instead, if you prefer. The vaccine is equally effective delivered both ways.

Are the Mpox Vaccines Safe for Pregnant People?

There isn’t enough data on Jynneos in humans to determine its safety in pregnant populations, but animal studies have not found any increased risk of birth defects or miscarriages in those that received the vaccine while pregnant. ACAM2000 may cause harm to a fetus, though it also has not been studied in pregnant patients.