Breakthrough CMV vaccine offers hope to pregnant women

Science and Health

Moderna’s final research stages on their vaccine against the deadly CMV virus are underway. The vaccine has so far shown to be safe, triggering strong immune responses capable of combating the virus.

The vaccine, known as mRNA-1647, utilizes the same technology as Moderna’s COVID-19 vaccines. It stimulates the body to produce antibodies that neutralize the virus, while also mobilizing white blood cells to eliminate it. These antibodies remain in the body as a lasting “immune memory,” ready to fend off future invasions by the same virus.

The vaccine’s initial phase focused on safety, beginning in 2019. Results indicated that it was safe and led to an increase in antibodies against the CMV virus, both in healthy individuals and pregnant women. A subsequent phase in 2020 involving 252 volunteers confirmed the vaccine’s safety and efficacy in antibody production. The final phase, encompassing around 8,000 participants in the USA and Europe, is expected to conclude within months. Following this, approximately one more year will be needed for the FDA to finalize its approval process.

“CMV infection during pregnancy can significantly harm the fetus,” said Prof. Tal Biron-Shental, chairwoman and director of the Obstetrics and Gynecology Division at Meir Medical Center, Kfar Saba, affiliated to Tel –Aviv University.

Moderna’s logo is reflected in a drop on a syringe needle in this illustration taken November 9, 2020 (credit: REUTERS/ DADO RUVIC)

“While most pregnant women who contract the virus do not transmit it to their fetus, there is no reliable way to determine this until signs of fetal damage appear on an ultrasound, sometimes only detectable after birth.”

Affected fetuses may suffer from conditions including deafness, blindness, and extensive brain damage. “There are new treatment studies, but they are only applicable to women infected close to their pregnancy,” Biron-Shental added. “Thus, prevention is the best strategy, making vaccination a key tool in preventing maternal illness and subsequent fetal harm. Given that Moderna’s vaccine employs a technique similar to that used for the coronavirus vaccine, we are fully confident in its safety and hopeful for its proven efficacy soon.”

Questions and answers about the Miscarriage Virus

What is CMV? The cytomegalovirus is one of the most prevalent viruses, with at least half of women expected to contract it at some point. For some, it causes no illness; for others, it can lead to mild flu-like symptoms or more severe conditions like the “kissing disease,” similar to symptoms caused by the EBV virus. However, CMV can be much more dangerous for newborns.


How does fetal infection occur? Transmission to the newborn can happen through the placenta during pregnancy or during birth.

How to detect infection in pregnant women? Gynecologists direct suspected cases to undergo serology tests, measuring antibodies against CMV in the blood and their ratios. Suspicion of recent infection could lead to further testing for the virus’s presence in the amniotic fluid.

What are the symptoms in newborns? While 85% of infected newborns show no symptoms, the remaining 15% may experience significant health issues, including organ enlargement, jaundice, and brain damage. CMV is the leading cause of congenital deafness.

Why can’t antibiotics be used? Antibiotics are ineffective against viruses, including CMV. Recent developments in antiviral treatments show promise, especially when administered close to pregnancy.

Treatment for infected newborns involves antiviral medications such as Ganciclovir or Valganciclovir, which help reduce deafness risks. These treatments require close monitoring and frequent blood tests to manage potential side effects.