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/ Making Strides Toward CMV Prevention
26 October 2021

Making Strides Toward CMV Prevention

Jacqueline Miller
MD, SVP, Infectious Disease Development
Lori Panther
Director, Clinical Development, VP, Infectious Diseases

With respiratory virus infections like SARS-CoV-2 (the virus that causes COVID-19) and influenza, your body is able to clear the virus as you recover. You remain virus-free until the next time you are infected. However, some viral infections become latent in your body, which means that once you are infected, you are infected for life. The virus may be quiet for years, but it can reactivate during times of stress.

Cytomegalovirus, or CMV, is a latent virus. More than half of people over the age of 40 in the U.S. have been infected with CMV in childhood or adulthood, and the vast majority did not notice any symptoms when they were infected. However, infants who were infected with CMV in utero can have serious and long-term health problems and disabilities from congenital CMV infection. This is because CMV has the possibility to interfere with the normal development of a fetus and can lead to deafness, seizures and developmental delay.

Congenital CMV is the leading infectious cause of birth defects in the U.S. and yet, 91% of women have never heard of it.¹ Together we can change that.

1 in 200 babies

Today, we’re working to prevent CMV infection in two key ways: 

First, this week marks another exciting milestone for our CMV Program at Moderna with the announcement of the start of our Phase 3 “CMVictory” clinical trial of our vaccine candidate, mRNA-1647, to test its efficacy to prevent CMV infection. We plan to enroll approximately 6,900 women from approximately 150 sites across the U.S., Europe and Asia-Pacific into the study. This is an exciting opportunity to build on the progress of our Phase 1 and Phase 2 mRNA-1647 studies, which indicated the ability to induce functional antibodies against CMV with an acceptable safety profile. Most recently, during Moderna’s annual Vaccines Day in April 2021, we announced an important clinical milestone with new 7-month interim data from our Phase 2 mRNA-1647 study.  

mRNA-1647 encodes two key CMV proteins that help the virus infect human cells: one is a complex protein made of five protein subunits assembled together, called pentamer, and the other is glycoprotein B, or gB. The pentamer antigen is essential in helping CMV infect epithelial cells (the cells lining our skin, nose and mouth) and endothelial cells, and the gB antigen is particularly effective at helping CMV infect fibroblasts.

mRNA encoding for Pentamer and gB

A safe and effective vaccine that stimulates strong antibody responses against pentamer and gB antigens may substantially decrease CMV infections. The CMVictory trial will allow us to move closer to addressing this significant and unmet public health concern, with our end goal of licensing a safe and effective vaccine against CMV for women of childbearing age that will potentially have a major impact on the health of children worldwide.

The development of a vaccine to prevent congenital CMV infection has been designated a highest priority by the National Academy of Medicine for two decades. And while several CMV vaccines have been developed by pharmaceutical companies over the years, none have succeeded in the clinic to date.

For our CMVictory trial, we have incorporated learnings from COVE, our Phase 3 pivotal efficacy trial to prevent COVID-19. We are committed to honoring the importance and impact of trial diversity by introducing demographic enrollment goals in the CMVictory trial. We will be transparent in our progress and hold ourselves accountable to meeting these goals and ensuring participation is representative of our diverse society. This is especially important as CMV disproportionately impacts diverse populations—for example, the rate of congenital CMV infection is twice as high in Black infants compared to the rest of the infant population.²  Of the 6,900 women who will enroll in the trial, we are committed to at least 42% representing Persons of Color.

To learn more about clinical trials by Moderna, visit

A second important way we are working to prevent CMV infection, while advancing our CMV vaccine candidate, is through education via

Source: NowThisNews

At Moderna, we obsess over learning and relentlessly seek information. The more people are educated about CMV, the better chance we have at reducing the spread we have at reducing the spread.

Because very young children infected with CMV can have the virus in their saliva or urine and can spread CMV infection to adults, some ways to help prevent CMV infection in women of childbearing age are to practice simple hygiene habits, like not sharing food or food utensils, toothbrushes, or pacifiers with a child; to avoid contact with saliva when kissing a child; and to frequently wash hands when caring for a child.

To help get the word out, we’ve put together a series of ready-to-post, bite-sized facts and infographics—all made to easily share online with friends, followers and connections.

We are deeply encouraged by the strides being made toward the prevention of CMV each day. Our deepest gratitude goes to the trial participants and the CMV families for their support and partnership!

Forward-Looking Statement

This post contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including statements regarding: the Company’s development of a vaccine against cytomegalovirus, or CMV (mRNA-1647); the conduct of the Phase 3 clinical trial for mRNA-1647, including number of participants to be enrolled, diversity targets, geographies and number of sites; the ability of mRNA-1647 to potentially protect against CMV infection, and its safety profile; the potential for approval of mRNA-1647 and its potential impact on curbing CMV infection rates. The forward-looking statements in this post are neither promises nor guarantees, and you should not place undue reliance on these forward-looking statements because they involve known and unknown risks, uncertainties, and other factors, many of which are beyond Moderna’s control and which could cause actual results to differ materially from those expressed or implied by these forward-looking statements. These risks, uncertainties, and other factors include those other risks and uncertainties described under the heading “Risk Factors” in Moderna’s most recent Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (SEC) and in subsequent filings made by Moderna with the SEC, which are available on the SEC’s website at Except as required by law, Moderna disclaims any intention or responsibility for updating or revising any forward-looking statements contained in this post in the event of new information, future developments or otherwise. These forward-looking statements are based on Moderna’s current expectations and speak only as of the date hereof.