Preventing CMV (cytomegalovirus) comes down to reducing your contact with the bodily fluids that carry it, particularly saliva and urine from young children. About 83% of people worldwide have been infected at some point, and for most healthy adults it causes no symptoms. But for pregnant women, transplant recipients, and people with weakened immune systems, a new CMV infection can have serious consequences. CMV is the most common infectious cause of birth defects in the United States.
How CMV Spreads
CMV travels through saliva, urine, blood, tears, semen, and breast milk. Young children are the most common source of transmission because they shed the virus in their saliva and urine for months or even years after infection, often with no visible symptoms. A toddler who drools on a toy, shares a cup, or needs a diaper change can easily pass the virus to a caregiver.
Other transmission routes include sexual contact, blood transfusions, organ transplants, and breastfeeding. During pregnancy, the virus can cross the placenta and infect the developing baby. Once you’re infected, CMV stays in your body for life in a dormant state, like other herpes viruses, and can occasionally reactivate.
Hygiene Steps That Actually Work
Hand washing is the single most effective everyday measure. Soap and water works better than alcohol-based hand sanitizer for removing CMV, especially when your hands are visibly dirty. Lather for at least 15 seconds. Wash your hands every time you change a diaper, wipe a child’s nose or drool, handle a used tissue, or touch a toy that’s been in a child’s mouth.
Beyond hand washing, these habits reduce your risk:
- Don’t share utensils, cups, or food with young children. Finishing a toddler’s leftover snack or using the same spoon exposes you directly to their saliva.
- Avoid kissing young children on or near the mouth. Kiss on the forehead or top of the head instead.
- Don’t put a child’s pacifier in your own mouth.
- Clean surfaces that may have contacted saliva or urine. Countertops, changing tables, toys, and doorknobs should be wiped regularly with a standard household disinfectant.
These precautions matter most if you’re pregnant, planning to become pregnant, or have a weakened immune system. For the average healthy adult, CMV infection rarely causes problems, so extreme measures aren’t necessary.
How Long CMV Survives on Surfaces
CMV can remain infectious on everyday objects longer than most people expect. Research published in The Journal of Infectious Diseases tested the virus on common household materials and found it survived up to 6 hours on cloth, rubber, and food items like crackers. On glass and plastic, it lasted up to 3 hours. On metal and wood, it died within 1 to 2 hours.
The key factor is moisture. CMV stays viable as long as a surface remains wet. Even after a surface looks dry, glass, cloth, and plastic retained infectious virus for 1 to 2 hours. This is why cleaning up drool, wiping down toys, and washing cloth items matters. A wet washcloth sitting on a counter or a slobbered-on stuffed animal can carry live virus for hours.
Prevention During Pregnancy
Pregnant women who catch CMV for the first time have the highest risk of passing it to their baby, which can cause hearing loss, developmental delays, and other birth defects. Women who already carry the virus from a past infection can also pass it during reactivation, though the risk of serious harm to the baby is lower.
The hygiene steps above are especially important if you’re pregnant and have a toddler at home or work in childcare. The CDC specifically recommends avoiding contact with children’s saliva and urine, not sharing utensils with toddlers, and washing hands thoroughly after every diaper change or face wipe. These aren’t dramatic lifestyle changes, but they require consistency. It’s easy to absentmindedly taste your child’s food or wipe their mouth with your bare hand.
If you want to know whether you’ve had CMV before, a blood test can check for antibodies. A positive IgG result means you were infected at some point in the past. A positive IgM result suggests a recent or active infection, though false positives are common with IgM testing. When both markers are present, a follow-up test called an IgG avidity test helps clarify timing: low avidity points to a recent infection (within the last 3 to 4 months), while high avidity indicates the infection happened further in the past. Routine CMV screening during pregnancy is not standard practice in most countries, but you can discuss testing with your provider if you have risk factors.
Precautions for Childcare Workers
People who work in daycare or early childhood settings face occupational exposure to CMV on a daily basis. OSHA recommends that childcare facilities develop infection control plans and treat all children’s body fluids as potentially infectious.
Practical steps for the workplace include wearing disposable gloves (nitrile or vinyl, not latex) during diaper changes and when wiping noses or cleaning up spit. Discard gloves immediately after each use and wash your hands with soap and water afterward. Gloves are not a substitute for hand washing since small tears or contamination during removal can still transfer the virus. Disinfect shared surfaces, toys, and frequently touched objects like faucet handles and doorknobs regularly throughout the day. Avoid sharing food, drinks, or utensils with the children in your care.
Prevention After Organ Transplant
CMV is a major concern after organ and bone marrow transplants because the immune-suppressing medications that prevent organ rejection also allow dormant CMV to reactivate. Transplant recipients who have never had CMV but receive an organ from a donor who carries it are at the highest risk.
For these patients, prevention is medical rather than behavioral. Antiviral medications are given as prophylaxis, typically starting right after transplant and continuing for several months. The specific medication and duration depend on the type of transplant and the patient’s CMV status. This is managed entirely by the transplant team and adjusted based on regular blood monitoring for signs of viral activity.
Vaccine Progress
No CMV vaccine is available yet, but several candidates are in advanced testing. The furthest along is an mRNA vaccine developed by Moderna (mRNA-1647), currently in a phase III clinical trial with results expected in 2025. An earlier candidate, a whole-virus vaccine called V160, showed 42% effectiveness against primary CMV infection in a phase II trial in women of childbearing age, though its future development is uncertain. Other approaches being tested include a protein-based vaccine delivered by a virus-like particle (in phase I trials) and a vaccine called Triplex, designed specifically for transplant patients, which is in phase II trials for liver transplant recipients.
A vaccine would transform CMV prevention, especially for pregnant women and transplant patients. But until one is approved, hygiene remains the primary tool for most people.