(DDM) — In a major blow to its post-pandemic ambitions, Moderna Inc. has announced that its much-anticipated cytomegalovirus (CMV) vaccine, designed to prevent a common virus linked to severe birth defects, has failed to meet its main goal in a late-stage clinical trial.
Diaspora Digital Media (DDM) gathered from a statement released by the biotechnology giant on Tuesday that the vaccine, based on mRNA technology similar to Moderna’s COVID-19 shot, showed disappointing results, with an efficacy rate ranging between 6% and 23%, far below the company’s target.
The study’s primary endpoint, preventing CMV infections in women of childbearing age, was not achieved, marking a significant scientific and commercial setback for Moderna, which has been seeking to diversify its mRNA vaccine portfolio beyond COVID-19.
CMV, or cytomegalovirus, is a common viral infection that often goes unnoticed in healthy adults but can cause severe developmental disorders, hearing loss, and microcephaly in newborns if transmitted from a mother during pregnancy.
Globally, CMV is considered one of the leading infectious causes of birth defects, affecting an estimated one in every 200 infants.
Despite decades of research, there has never been an approved vaccine against CMV, making Moderna’s trial a highly anticipated test of whether mRNA technology could revolutionize maternal and neonatal health.
According to company insiders cited by Bloomberg, the failure represents one of Moderna’s biggest scientific disappointments since the pandemic, particularly as investors and public health experts had hoped the CMV vaccine would become the first of its kind to be licensed.
The late-stage trial involved thousands of women across several countries, tracking whether those who received the vaccine developed CMV infections compared to those given a placebo.
Moderna’s Chief Executive Officer, Stéphane Bancel, reportedly expressed disappointment but reaffirmed the company’s commitment to further developing mRNA-based vaccines for other infectious diseases.
“This result is disappointing, but it provides invaluable data that will inform the next generation of mRNA vaccines,” Bancel said. “We remain committed to addressing unmet medical needs through innovative science.”
Analysts told DDM that the failed trial may delay Moderna’s diversification strategy and affect its stock value, which has already suffered as demand for COVID-19 boosters declines worldwide. The company has been under pressure to prove the broader potential of its mRNA platform, which was hailed as revolutionary during the pandemic.
Experts say the CMV setback could also raise questions about the scalability of mRNA-based vaccines for non-pandemic diseases, especially those requiring long-term immune protection rather than rapid outbreak response.
Dr. Rachel Morrison, a virologist at the Harvard T.H. Chan School of Public Health, explained that CMV presents unique challenges. “Unlike acute respiratory viruses, CMV establishes latent infections and reactivates periodically,” she told DDM.
“This makes it much harder for vaccines to offer complete protection.”
The CMV trial failure adds to a string of challenges Moderna has faced in recent months, including sluggish vaccine sales, rising research costs, and competition from Pfizer and BioNTech in the mRNA vaccine space.
The company has also been exploring mRNA-based flu and RSV vaccines, with mixed early results.
Still, public health officials stress that the data could help future efforts. “Even though this trial didn’t hit its target, it’s an important step forward,” said Dr. Sarah Jackson, a maternal health researcher at Johns Hopkins University. “We’re learning more about how mRNA platforms behave in complex infections like CMV.”
Moderna’s CMV program was considered one of its most promising post-COVID ventures, with analysts estimating potential annual sales of up to $2 billion if successful.
The latest development, however, may force the company to rethink its research priorities and timelines for other vaccine candidates.
In the meantime, the World Health Organization (WHO) continues to list CMV prevention as a critical global health goal, urging pharmaceutical companies to pursue new vaccine technologies that can protect pregnant women and newborns from the infection’s devastating effects.
As of now, experts note that the only prevention strategies available are hygiene-based, such as avoiding contact with saliva and urine from young children, which offer limited protection for expectant mothers.
With this setback, Moderna faces the challenge of rebuilding investor confidence and proving that its mRNA expertise extends beyond COVID-19.
According to analysts, the company’s future success may depend on adapting its platform to tackle persistent viral diseases rather than short-term pandemics.
While the CMV vaccine failure represents a serious blow, Moderna insists it will continue investing in next-generation candidates and explore potential modifications to improve immune responses in future trials.
