Could the Mpox Outbreak Reach the U.S.?

The most accurate answer to the question “Could the mpox outbreak reach the U.S.?” is no longer hypothetical: it already has.

Clade I mpox cases have been identified in the United States, while clade IIthe strain behind the major 2022 global outbreakhas never completely stopped circulating here. That does not mean the country is staring down another pandemic or that Americans should begin disinfecting their groceries like it is spring 2020 all over again. It does mean travelers, clinicians, public health agencies, and people at elevated risk should pay attention.

By June 2026, the Centers for Disease Control and Prevention had reported more than 20 U.S. clade I cases. These infections were associated directly or indirectly with travel to areas experiencing outbreaks, including parts of Central and Eastern Africa and Western Europe. The CDC expects additional imported or linked cases, but it continues to describe the risk to most people in the United States as low.

In other words, mpox can cross borders. It has done so repeatedly. However, arriving in a country and spreading widely through its general population are two very different public health events.

What Is Happening With Mpox Around the World?

Mpox is caused by monkeypox virus, an orthopoxvirus related to the virus that caused smallpox. It can spread between people and, in some settings, from infected animals to people.

Scientists classify monkeypox viruses into two major groups: clade I and clade II. Each group also has subclades, including Ia, Ib, IIa, and IIb. The terminology sounds like somebody alphabetized a bowl of soup, but the distinctions matter because the clades have different histories, transmission patterns, and rates of severe disease.

Clade I

Clade I has historically circulated in Central Africa. Large outbreaks involving clades Ia and Ib expanded in the Democratic Republic of the Congo and neighboring countries beginning in 2023 and 2024. Clade Ib demonstrated an ability to spread efficiently through sustained close physical and sexual contact, and travel-associated infections were subsequently identified on several continents.

By June 2026, more than 55,000 confirmed clade I cases and over 150 deaths had been reported globally since January 2024. Recent travel-associated clade Ib infections in high-income countries have generally produced relatively mild illness, with no deaths reported among those exported cases. That is reassuring, although it does not make the virus harmless.

Clade II

Clade IIb caused the international outbreak that surged in 2022. It spread primarily through intimate and sexual contact, disproportionately affecting gay, bisexual, and other men who have sex with men. Cases dropped dramatically after vaccination campaigns, behavioral changes, improved awareness, and immunity following infection.

However, “dropped dramatically” is not the same as “vanished.” U.S. clade II infections have continued at low levels. Since October 2024, monthly counts have generally remained around 200 cases or fewer, and approximately 1,700 to 2,800 U.S. cases were reported annually from 2023 through 2025.

Has Clade I Mpox Already Reached the United States?

Yes. The first recognized U.S. clade I case was reported in California in November 2024 in a traveler who had recently returned from Eastern Africa. Additional infections followed.

In October 2025, California health investigators also identified clade Ib infections in three unrelated people without a recognized international travel history. That finding provided evidence of limited community transmission. Later U.S. cases were associated with travel to outbreak areas or contact with travelers, and the frequency of reported clade I infections increased during the first half of 2026.

This situation supports two conclusions that may sound contradictory but are both true:

• Clade I can reach the United States and can occasionally spread locally.
• There is no evidence that it is spreading widely through the general U.S. population.

Public health risk is rarely a simple on-or-off switch. It is more like a dimmer: risk changes according to exposure, travel, sexual networks, vaccination status, local transmission, and access to prompt testing.

How Could Mpox Spread in the U.S.?

Mpox is not usually transmitted through brief, ordinary encounters such as walking past someone at a store. The virus spreads most efficiently through close, sustained contact.

Direct contact with a rash

Touching mpox lesions, scabs, or bodily fluids is a major route of transmission. Skin-to-skin contact during sex is especially efficient because it can involve prolonged friction and contact with lesions that may be difficult to see.

Intimate or prolonged face-to-face contact

Kissing, cuddling, sexual activity, massage, and extended close contact can create opportunities for transmission. Respiratory secretions may contribute during prolonged face-to-face interaction, but mpox does not behave like measles, which can float through indoor air and infect people at a distance.

Contaminated personal items

Clothing, bedding, towels, sex toys, and other objects that have contacted lesions or bodily fluids may carry infectious material. This route is possible, although direct physical contact is generally the larger concern.

Pregnancy and animal contact

A pregnant person can pass the virus to a fetus. Infection may also occur after contact with certain infected animals, particularly in regions where the virus circulates in wildlife.

Why a Major Nationwide Outbreak Is Not Inevitable

The United States has several defenses that did not exist when the 2022 outbreak began attracting attention.

Doctors now recognize that mpox may present as one lesion rather than a dramatic head-to-toe rash. Public health laboratories can test samples and identify viral clades. Higher-risk communities have more experience recognizing symptoms, discussing exposure, and seeking vaccination. Health departments have contact-tracing protocols, and the federal government maintains vaccine and treatment resources.

The United States also has the JYNNEOS vaccine. CDC guidance indicates that mpox vaccines are expected to provide protection across clades and subclades. JYNNEOS is administered as a two-dose series, with the doses normally given 28 days apart.

Vaccination is not an invisible force field. Breakthrough infections occur. Even so, U.S. studies have found substantial protection from two doses, and infections among fully vaccinated people have generally been uncommon and less severe. In one multijurisdictional analysis, estimated protection reached approximately 86% after two doses. Fewer than 1% of fully vaccinated people were reported to have developed breakthrough mpox during a CDC review covering May 2022 through May 2024.

Who Faces the Greatest Risk?

Anyone can acquire mpox after a qualifying exposure. The virus does not check identity cards, social media bios, or relationship status. Risk depends on behavior and contact, not on belonging to a particular community.

Current U.S. transmission nevertheless remains concentrated in certain sexual networks. The CDC considers the risk from clade I low for most Americans and low to moderate for men who have sex with men. People may have an elevated chance of exposure if they:

• Have multiple or new sexual partners.
• Have close contact with someone who has mpox symptoms.
• Attend events where intimate skin-to-skin contact occurs.
• Travel to an area with active clade I or clade II transmission.
• Work directly with orthopoxviruses in certain laboratory settings.
• Share bedding, clothing, or personal objects with an infected person.

People who are severely immunocompromised, including some individuals with advanced or poorly controlled HIV, face a greater risk of prolonged or life-threatening illness. Pregnant people, young children, and people with certain extensive skin conditions may also require closer medical assessment after exposure or infection.

Mpox Symptoms Americans Should Recognize

Symptoms generally begin within 21 days of exposure. Some people first develop fever, chills, swollen lymph nodes, headache, muscle aches, sore throat, congestion, or fatigue. Others notice a rash before feeling illor never develop obvious flu-like symptoms at all.

The rash may appear on the face, hands, feet, mouth, genitals, or around the anus. It can consist of dozens of lesions, several lesions, or a single spot that resembles a pimple, blister, ingrown hair, or common sexually transmitted infection.

Lesions typically progress from flat spots to raised bumps, fluid-filled blisters, pustules, and scabs. They may be intensely painful before becoming itchy during healing. Symptoms commonly last two to four weeks, and a person may remain contagious until every lesion has healed, all scabs have fallen off, and fresh skin has formed.

Seek prompt medical advice for an unexplained rash, especially after recent travel, intimate contact with a new partner, or exposure to someone diagnosed with mpox. Do not pop, shave over, or casually introduce suspicious lesions to the entire contents of the bathroom medicine cabinet. Cover them, limit close contact, and arrange testing.

Testing and Treatment

Clinicians normally diagnose mpox by swabbing one or more lesions and sending the samples for molecular testing. A visual examination alone may be misleading because herpes, syphilis, chickenpox, allergic reactions, and bacterial skin infections can resemble mpox.

Most patients recover with supportive care. Treatment may include pain control, hydration, wound care, and management of complications. Severe rectal, genital, eye, or throat involvement may require specialist care or hospitalization.

Tecovirimat, also known as TPOXX, was originally developed for smallpox and has been used for mpox through special access pathways. Recent randomized trials found that tecovirimat alone did not shorten lesion healing or reduce pain in typical mild-to-moderate clade II disease. It also failed to improve lesion resolution in a clade I trial in the Democratic Republic of the Congo.

Those findings do not mean clinicians have nothing to offer. Tecovirimat and other medical countermeasures may still be considered in selected people with severe disease or a high risk of dangerous complications. Treatment decisions should be made by specialists using current public health guidancenot by purchasing mystery capsules from an online seller whose medical credentials consist of a lightning-bolt logo.

How to Reduce Your Risk

Complete the recommended vaccine series

People who meet current risk criteria should receive both JYNNEOS doses unless a healthcare professional recommends otherwise. A single dose offers some protection, but two doses provide stronger protection. Routine boosters are not currently recommended for most people who completed the series.

Consider vaccination before higher-risk travel

Travelers visiting places with ongoing transmission should review destination-specific health guidance. People likely to have sexual or other close physical exposure during travel should discuss vaccination early enough to complete the series before departure.

Pay attention to skin symptoms

Avoid sexual or intimate contact when you or a partner has a new, unexplained rash. Remember that lesions may be hidden inside the mouth, throat, rectum, or genital area.

Communicate without stigma

Ask partners about recent symptoms and exposures in a straightforward way. Public health conversations work better when they sound like healthcare rather than a courtroom cross-examination.

Act quickly after an exposure

Contact a healthcare professional or health department after known exposure. Post-exposure vaccination may prevent illness or reduce its severity when given promptly.

Could Mpox Become a Large U.S. Outbreak Again?

It is possible, but it is not the most likely scenario under current conditions.

A larger outbreak would become more likely if vaccination rates declined, cases circulated undetected, testing access deteriorated, or the virus entered closely connected networks with low immunity. International travel and expanding transmission in Europe or Africa could introduce additional infections.

On the other hand, rapid diagnosis, targeted vaccination, honest risk communication, contact tracing, and voluntary temporary changes in close-contact behavior can interrupt transmission. These measures helped bring down the 2022 outbreak without broad lockdowns or restrictions on ordinary daily life.

The proper response is therefore preparedness without panic. Mpox deserves attention because delayed recognition allows it to spread. It does not deserve sensationalism that suggests every handshake is a medical emergency.

Experience and Lessons From Previous Mpox Outbreaks

Lesson 1: Communities respond faster when officials communicate honestly

The 2022 U.S. experience showed that vague warnings were less helpful than practical guidance. People wanted to know how the virus spread, which activities carried the greatest risk, where vaccines were available, and what a suspicious lesion actually looked like.

When sexual health clinics, LGBTQ+ organizations, event organizers, healthcare workers, and local advocates shared direct information, many people voluntarily reduced high-risk contact, checked symptoms, and sought vaccination. That community participation helped cases fall. The experience demonstrated that people are capable of making sensible health decisions when officials provide useful facts instead of foggy slogans.

Lesson 2: Stigma makes outbreaks harder to control

Because many early cases occurred among gay and bisexual men, some public discussions slipped into blame. That was both unfair and epidemiologically clumsy. A virus may become concentrated in a network because of contact patterns, not because members of that network are somehow responsible for its existence.

Stigmatizing language discourages testing, partner notification, and honest conversations with clinicians. It may also create a false sense of safety among people outside the group receiving attention. The useful message is simple: anyone can get mpox after exposure, while some people currently have a higher statistical risk and may benefit most from vaccination.

Lesson 3: Vaccine access must be easy, not theoretical

During the early 2022 response, many people struggled to find appointments, determine eligibility, or complete the second dose. A vaccine does little public health magic while sitting in a freezer or hiding behind a confusing online portal.

Successful programs brought vaccination into sexual health clinics, community centers, pharmacies, Pride events, and other familiar settings. They used reminders for second doses and reduced unnecessary paperwork. These experiences remain relevant as clade I cases appear through international travel and limited local transmission.

Lesson 4: Clinicians must expect unusual presentations

Older medical descriptions often emphasized fever followed by a widespread rash. The 2022 outbreak taught clinicians that mpox could present as a small number of genital or anal lesions, severe rectal pain, a sore throat, or a single bump. Some patients had no obvious fever.

That experience improved diagnostic awareness, but knowledge can fade as cases become less common. Continuing education matters because a clinician who does not consider mpox is unlikely to order the correct test.

Lesson 5: Global control protects the United States

Perhaps the largest lesson is that infectious diseases cannot be managed permanently at an airport gate. When countries experiencing sustained transmission lack vaccines, diagnostics, trained staff, or treatment resources, the virus gains more opportunities to spread and cross borders.

Supporting outbreak control in affected African countries is therefore not charity detached from American interests. It is a practical form of domestic protection. Reducing transmission at its source lowers the number of infections, the number of international introductions, and the chance that the virus will establish new transmission networks elsewhere.

The United States cannot guarantee that no traveler will ever arrive with mpox. It can help make those arrivals less frequent, identify them quickly, protect people at elevated risk, and prevent a handful of infections from becoming thousands.

Conclusion

Could the mpox outbreak reach the U.S.? It already has, in both travel-associated cases and limited local transmission. Clade II also continues to circulate at low levels. The more important question is whether these infections will expand into sustained, widespread transmission.

At present, the risk to most Americans remains low. The country has testing capacity, an effective two-dose vaccine, established surveillance, experienced health departments, and communities that learned valuable lessons during the 2022 outbreak.

People should watch for symptoms, obtain vaccination when eligible, seek care promptly after exposure, and follow travel guidance. That is vigilance, not panicand it is considerably more useful than treating every itchy spot as the opening scene of a disaster movie.