CDC Health Alert Network (HAN) Health Update: Potential Risk for New Mpox Cases

Potential Risk for New Mpox Cases


Date of Record: May 15, 2023


In the United States, cases of mpox (formerly monkeypox) have declined since peaking in August 2022, but the outbreak is not over. The Centers for Disease Control and Prevention (CDC) continues to receive reports of cases that reflect ongoing community transmission in the United States and internationally. This week, CDC and local partners are investigating a cluster of mpox cases in the Chicago area. From April 17 to May 5, 2023, a total of 12 confirmed and one probable case of mpox were reported to the Chicago Department of Public Health. All cases were among symptomatic men. None of the patients have been hospitalized. Nine (69%) of 13 cases were among men who had received 2 JYNNEOS vaccine doses. Confirmed cases were in 9 (69%) non-Hispanic White men, 2 (15%) non-Hispanic Black men, and 2 (15%) Asian men. The median age was 34 years (range 24–46 years). Travel history was available for 9 cases; 4 recently traveled (New York City, New Orleans, and Mexico).


Although vaccine-induced immunity is not complete, vaccination continues to be one of the most important prevention measures. CDC expects new cases among previously vaccinated people to occur, but people who have completed their two-dose JYNNEOS vaccine series may experience less severe symptoms than those who have not.


Spring and summer season in 2023 could lead to a resurgence of mpox as people gather for festivals and other events. The purpose of this Health Alert Network (HAN) Health Update is to inform clinicians and public health agencies about the potential for new clusters or outbreaks of mpox cases and to provide resources on clinical evaluation, treatment, vaccination, and testing. 



A global outbreak of mpox began in May 2022. Previous outbreaks in places where mpox is not endemic were mostly related to international travel; however, this outbreak spread rapidly across much of the world through person-to-person contact, disproportionately affecting gay and bisexual men, other men who have sex with men (MSM), and transgender people. Most patients with mpox have mild disease, although some, particularly those with advanced or untreated HIV infection, may experience more severe outcomes.


As of May 10, a total of 30,395 cases have been reported in the United States. This outbreak had a peak of about 460 cases per day in August 2022, and gradually declined, likely because of a combination of temporary changes in sexual behavior, vaccination, and infection-induced immunity[1,2]. However, CDC continues to receive reports of new cases and clusters in the United States and internationally.


Although approximately 1.2 million JYNNEOS mpox vaccine doses have been administered in the United States since the beginning of the outbreak, only 23% of the estimated population at risk for mpox has been fully vaccinated. Vaccine coverage varies widely among jurisdictions. The projected risk of a resurgent mpox outbreak is greater than 35% in most jurisdictions in the United States without additional vaccination or adapting sexual behavior to prevent the spread of mpox [3]. Resurgent outbreaks in these communities could be as large or larger than in 2022. 


To help prevent a renewed outbreak during the spring and summer months, CDC is urging clinicians to be on alert for new cases of mpox and to encourage vaccination for people at risk. If mpox is suspected, test even if the patient was previously vaccinated or had mpox. Clinicians should also refamiliarize themselves with mpox symptomsspecimen collectionlaboratory testing procedures, and treatment options


Recommendations for Clinicians Evaluating and Treating Patients

Conduct a thorough patient history to assess possible mpox exposures or epidemiologic risk factors. Mpox is usually transmitted through close, sustained physical contact and has been almost exclusively associated with sexual contact in the current global outbreak. It is important to take a detailed sexual history for any patient with suspected mpox. 


Perform a complete physical examination, including a thorough skin and mucosal (e.g., oral, genital, anal) examination. Doing so can detect lesions of which the patient may be unaware.


Consider mpox when determining the cause of a diffuse or localized rash, including in patients who were previously infected with mpox or vaccinated against mpox. Differential diagnoses include herpes simplex virus (HSV) infection, syphilis, herpes zoster (shingles), disseminated varicella-zoster virus infection (chickenpox), molluscum contagiosum, scabies, lymphogranuloma venereum, allergic skin rashes, and drug eruptions. Specimens should be obtained from lesions (including those inside the mouth, anus, or vagina), if accessible, and tested for mpox and other sexually transmitted infections (STI), including HIV, as indicated. The diagnosis of an STI does not exclude mpox, as a concurrent infection may be present.


Patients with mpox benefit from supportive care and pain control. Mpox can commonly cause severe pain and can affect anatomic sites, including the anus, genitals, and oropharynx, which can lead to other complications. Assess pain in all patients with mpox virus infection and recognize that substantial pain may exist from mucosal lesions not evident on physical exam. Topical and systemic strategies should be used to manage pain. Pain management strategies should be tailored to the needs and context of an individual patient.


Tecovirimat is considered first-line among options that have not been approved by the U.S. Food and Drug Administration to treat eligible patients with mpox. If a clinician intends to prescribe oral tecovirimat, consider seeking access through enrollment in the AIDS Clinical Trials Group (ACTG) Study of Tecovirimat for Human Monkeypox Virus (STOMP) so that the trial can determine efficacy of this drug. This trial includes a placebo-controlled, randomized arm, and an open-label option for individuals with severe disease or those who decline randomization. Remote enrollment is available. For patients not eligible for the STOMP trial or who decline to participate, stockpiled oral tecovirimat is available upon request for mpox patients who meet treatment eligibility (e.g., have severe disease or are at increased risk for severe disease) under CDC’s Expanded Access Investigational New Drug (IND) protocol. More information about evaluating and treating patients can be found on the CDC mpox Clinical Guidance web pages. 


Clinicians should notify their state or local health departments of any suspected or confirmed mpox cases (via 24-hour Epi On Call contact list). 


Recommendations for Vaccinating Patients

JYNNEOS vaccine can be given as post-exposure prophylaxis (PEP) both to people with known or presumed exposure to the mpox virus. Vaccine can also be given to people with certain risk factors and recent experiences that may make them more likely to have been exposed to mpox. As PEP, vaccine should be given as soon as possible, ideally within 4 days of exposure; however, administration 4 to 14 days after exposure may still provide some protection against mpox. People who are vaccinated should continue to avoid close, skin-to-skin contact with someone who has mpox. JYNNEOS involves 2 vaccine doses given 28 days apart; peak immunity is expected 14 days after the second dose [4]. 


Previous studies have suggested that JYNNEOS vaccination is protective against mpox. When combined with other prevention measures, vaccination prior to exposure and PEP vaccination strategies might help control outbreaks by reducing transmission of the mpox virus, preventing disease, or reducing disease severity and hospitalization. Duration of immunityafter one or two doses of JYNNEOS is unknown.


Currently, CDC does not recommend routine immunization against mpox for the general public. Mpox vaccination should be offered to people with high potential for exposure to mpox: 

  • People who had known or suspected exposure to someone with mpox.
  • People who had a sex partner in the past 2 weeks who was diagnosed with mpox.
  • Gay, bisexual, and other MSM, and transgender or nonbinary people (including adolescents who fall into any of these categories) who, in the past 6 months, have had
    • A new diagnosis of one or more sexually transmitted diseases (e.g., chlamydia, gonorrhea, syphilis).
    • More than one sex partner.
  • People who have had any of the following in the past 6 months
    • Sex at a commercial sex venue.
    • Sex in association with a large public event in a geographic area where mpox transmission is occurring.
    • Sex in exchange for money or other items.
  • People who are sex partners of people with the above risks.
  • People who anticipate experiencing any of the above scenarios.
  • People with HIV infection or other causes of immunosuppression who have had recent or anticipate potential mpox exposure.
  • People who work in settings where they may be exposed to mpox.
    • People who work with orthopoxviruses in a laboratory.


Extensive risk assessment should not be conducted in people who request vaccination to avoid the barriers created by the stigma experienced by many who could benefit from vaccination. People in the community at risk (e.g., gay, bisexual, or other MSM; transgender or nonbinary people) asking for vaccination is adequate attestation to individual risk of mpox exposure. People who previously received only one JYNNEOS vaccine dose should receive a second dose as soon as possible. 


For More Information 


Clinical Advisory - August 17, 2022

Important update regarding monkeypox vaccination with JYNNEOS in Massachusetts. On August 9, 2022, the Center for Disease Control (CDC) and the Federal Drug Administration (FDA) released an Emergency Use Authorization (EUA) allowing an alternative lower dose intradermal vaccination regimen in people 18 years and over and allowing the use of the JYNNEOS vaccine in individuals younger than 18 years. 

Providers administering JYNNEOS vaccine will begin utilizing this alternative dose vaccination regimen beginning August 18, 2022. 

Please visit CLINICAL ADVISORY for details.


Monkeypox image

In August of 2022, the United States declared its monkeypox outbreak a national public health emergency. While monkeypox has shown to be less contagious than other viruses such as COVID-19 and has not led to any deaths in the country, residents are asked to take its risk seriously.

The Town of Shrewsbury along with the Central MA Regional Public Health Alliance (CMRPHA) is prioritizing treatment and prevention efforts for populations currently at most risk, with a particular focus on individuals with multiple sexual partners; those in repeated close contact with others, including sports teams; and those living in close quarters, such as in group housing and dorms. The Alliance is seeking to expand its access to vaccines, and residents will be notified as its capacity increases.

This page includes up-to-date information and resources from the Centers for Disease Control and Prevention (CDC) and Massachusetts Department of Public Health (MDPH) about how monkeypox spreads, precautions to take and how to seek treatment.


Monkeypox is a rare disease caused by infection with the monkeypox virus, which can make people sick. Symptoms may include a rash, resembling pimples or blisters, often preceded by flu-like illness. Overall illness typically lasts 2 - 4 weeks. While some people experience mild symptoms, others may experience severe pain.


Monkeypox can be spread to anyone through close, personal, often skin-to-skin contact including:

  • Direct contact with rash, blisters or scabs.
  • Contact with surfaces and objects - such as clothing, bedding or towels - that have been used by an individual with monkeypox.
  • Prolonged contact with bodily fluids, such as through kissing.

Monkeypox can be easily passed between sexual partners due to close skin contact, and any person, regardless of gender identity or sexual orientation, can acquire and spread it.

A person with monkeypox can spread it to others from the time symptoms start until the rash has fully healed and a fresh layer of skin has formed.


Symptoms of monkeypox infection typically appear within 3 weeks of exposure and can include:

  • Fever
  • Chills
  • Swollen Lymph Nodes
  • Exhaustion
  • Muscle Aches and Backache
  • Headache
  • Respiratory Symptoms (e.g., sore throat, nasal congestion or cough)

Rash blisters appear 1 - 4 days later and can be located on or near the genitals or anus, as well as other areas like the hands, feet, chest, face or mouth. They can itch and be painful to the touch. The blisters will go through several stages before scabbing, falling off and healing.




The CDC recommends the following steps to protect yourself from getting monkeypox:

  1. Avoid close, skin-to-skin contact with people who have a rash that looks like monkeypox.
  2. Avoid contact with objects and materials that a person with monkeypox has used.
  3. Wash your hands often with soap and water or use an alcohol-based hand sanitizer, especially before eating or touching your face and after you use the bathroom.

The CDC also recommends vaccination for people who have been exposed to monkeypox and people who may be more likely to get monkeypox, which includes:

  • People who have been identified by public health officials as a contact of someone with monkeypox.
  • People who are aware that one of their sexual partners in the past 2 weeks has been diagnosed with monkeypox.
  • People who had multiple sexual partners in the past 2 weeks in an area with known monkeypox.
  • People whose jobs may expose them to orthopoxviruses.

Currently, high-risk individuals may contact AIDS Project Worcester at 508-755-3773 x113 to schedule a vaccine appointment. However, due to severely limited supply, availability is currently low.

Additional details on vaccine eligibility and other locations in Massachusetts offering appointments can be found on the MDPH Website


Any resident who suspects they have been infected should contact their healthcare provider as soon as possible and to avoid skin-to-skin contact with others until being examined. They should also alert anyone they may have been in close physical contact with about potential exposure. Anyone with monkeypox is urged to follow the CDC's Isolation Guidelines

While there is no current treatment specifically for monkeyox, antiviral drugs such as tecovirimat (TPOXX), may be recommended for people who are more likely to get severely ill, like patients with weakened immune systems.