Mpox Vaccine

When properly administered before or after a recent exposure, vaccines can be effective tools at protecting people against mpox illness. There are a few strategies being used in the United States to distribute and vaccinate at risk populations.

The first strategy is Mpox Vaccine Post-Exposure Prophylaxis (PEP), which is considered as “standard PEP” for mpox. Individuals are vaccinated following exposure to mpox to help prevent mpox illness. This is done through identification of contacts of confirmed or probable mpox cases, and then offering vaccine for PEP and monitoring of symptoms or early signs of illness in those contacts.

The CDC recommends exposed contacts receive the vaccine within 4 days from the date of exposure, for the best chance to prevent the onset of the disease. But when given between 4 and 14 days from exposure vaccination may still reduce symptoms of the disease, but may not prevent the disease. And many benefits will still outweigh risks when giving vaccine more than 14 days after exposure in some clinical settings. However, vaccination given after the onset of signs or symptoms of mpox is not expected to provide benefit. PEP is important in controlling outbreaks and preventing further transmission of mpox, especially when coupled with self-isolation and other prevention measures.

The second strategy is Outbreak Response Mpox Vaccine Post-Exposure Prophylaxis (PEP++). This is an expanded approach for the current outbreak. There are people with certain risk factors who are more likely to have recently been exposed to mpox, and PEP++ aims to reach these people for post-exposure prophylaxis even if they have not yet had documented exposure to someone with confirmed mpox. This strategy is primarily used in areas with large numbers of mpox cases, which suggests a higher level of mpox virus transmission. This strategy is also coupled with self-isolation and other prevention measures when symptoms first occur.

A third strategy is Mpox Vaccine Pre-Exposure Prophylaxis (PrEP), which is when vaccine is administered to someone at high risk for mpox. For the current mpox outbreak, PrEP is recommended for:

• Anyone regardless of sex, gender, or sexual orientation who:
  • Exchanged goods or services for sex in the last six months
    
  • Is living with HIV, especially persons with uncontrolled or advanced HIV disease
    
  • Is eligible or currently taking PrEP (pre-exposure prophylaxis) to help prevent infection with HIV
    
• Gay, bisexual, and other men who have sex with men, transgender, or nonbinary people who in the past six months have had:
  
  • A new diagnosis of one or more nationally reportable sexually transmitted diseases (i.e., acute HIV, chancroid, chlamydia, gonorrhea, or syphilis)
    
  • More than one sex partner
    
• Sexual partners of people with the above risks
  
• People who anticipate experiencing the above risks
  

CDC began posting preliminary data collected from 32 U.S. public health jurisdictions on rates of mpox cases by vaccination status. These data show that unvaccinated people had 14 times the risk of mpox disease compared to people who were vaccinated. Studies are currently underway to further demonstrate how well the vaccine can protect people. Vaccinated persons should still take additional precautions against mpox.

The ACIP recommends preexposure vaccination of people who are at risk for occupational exposure, such as laboratory workers. At this time, most clinicians in the United States and laboratorians not performing the orthopoxvirus generic test to diagnose orthopoxviruses, including mpox virus, are not advised to receive mpox vaccine PrEP.

There are currently two vaccines being used in the United States to prevent Mpox virus infection. The first is JYNNEOS, which has FDA approval for the prevention of Mpox virus infection. The second is ACAM2000, which is approved by the FDA for use against smallpox and has been made available for use against mpox under an Expanded Access Investigational New Drug application.

• Vaccination (CDC)
• Rates of Mpox Cases by Vaccination Status (CDC)