Cytomegalovirus (CMV) is a common virus, often without serious symptoms. However, this widespread infection can lead to significant complications in specific populations.
Understanding Cytomegalovirus (CMV)
CMV is a common herpesvirus, with over half of U.S. adults infected by age 40 and nearly one in three children by age five. It spreads through direct contact with body fluids such as saliva, urine, blood, semen, and breast milk. Close contact is the primary transmission route.
For most healthy individuals, CMV causes no symptoms or only mild, flu-like illness. However, the virus remains in the body for life, potentially reactivating. CMV concerns vulnerable groups, especially newborns and immunocompromised individuals. If a pregnant person acquires CMV for the first time, it can pass to the unborn baby, leading to congenital CMV (cCMV). This can cause serious health problems, such as hearing loss and developmental delays. Immunocompromised individuals, like transplant recipients, also face severe complications if CMV reactivates.
The Quest for a CMV Vaccine
Currently, no widely available, licensed vaccine exists for general use to prevent CMV infection. Developing a CMV vaccine is challenging due to its complex nature and large genome. However, significant progress has been made, with several vaccine candidates in various clinical trial stages.
Research focuses on glycoprotein B (gB) subunit vaccines, often with an adjuvant. This vaccine type has shown efficacy in preventing CMV acquisition and reducing viral parameters in transplant recipients. Messenger RNA (mRNA) technology is another promising approach, with an mRNA-based CMV vaccine candidate currently in Phase 3 trials. Other vaccine types, including live-attenuated, DNA, and vectored vaccines, are also being investigated.
The goal is to prevent congenital CMV infection by protecting pregnant individuals or reduce disease severity in immunocompromised patients.
Current Prevention Strategies
Since a broadly available vaccine is not yet a reality, current prevention efforts focus on practical hygiene measures to reduce CMV transmission. These strategies are particularly important for pregnant individuals and those who care for young children, as young children often shed the virus.
Key preventive actions include frequent handwashing after changing diapers, feeding young children, or handling toys. Avoid sharing food, drinks, eating utensils, or toothbrushes with young children. Kissing young children on the forehead rather than the lips can also help reduce exposure to saliva. These simple hygiene practices are currently the most effective defense against CMV infection and are recommended by health organizations.