In short
mRNA-1647 is an investigational messenger RNA (mRNA) vaccine being studied to prevent cytomegalovirus (CMV) infection. It contains six mRNAs encoding CMV proteins, including UL130. A Phase 3 trial enrolled 7,484 participants to evaluate its efficacy, safety, and immunogenicity.
Key points
- mRNA-1647 is an investigational mRNA vaccine against cytomegalovirus (CMV).
- The vaccine encodes six CMV proteins, including UL130, UL128, and UL131A.
- A Phase 3 trial enrolled 7,484 participants aged 16 to 40 years.
- The trial measured primary CMV infection as a key efficacy endpoint.
- The study is completed, with results reported on ClinicalTrials.gov.
What is mRNA-1647?
mRNA-1647 is an investigational messenger RNA (mRNA) vaccine being studied to prevent cytomegalovirus (CMV) infection. It is not yet authorised as a medicine. The vaccine contains six different mRNA molecules that encode human cytomegalovirus proteins: glycoprotein B, glycoprotein H, glycoprotein L, UL128, UL130, and UL131A. The European Medicines Agency (EMA) has accepted a modification of an agreed paediatric investigation plan for these mRNA components, indicating ongoing development of this vaccine for potential use in children.
How does mRNA-1647 work?
mRNA-1647 is an mRNA vaccine. The mRNAs in the vaccine instruct cells to produce six CMV proteins, including UL130, a protein involved in the virus's ability to enter cells. The immune system then recognises these proteins as foreign and develops antibodies and other immune responses against them. This is intended to prepare the body to fight off a future CMV infection. The UL130 protein is part of the pentameric complex, a group of five proteins the virus uses to infect certain cell types.
Which conditions is it studied for?
- Cytomegalovirus (CMV) infection — a common viral infection that can cause serious problems in unborn babies if a woman is infected during pregnancy, and in people with weakened immune systems.
How is mRNA-1647 given?
In the clinical trial, mRNA-1647 was given as an intramuscular injection. The trial used a three-dose schedule. A placebo arm received sodium chloride 0.9% solution for injection, also given intramuscularly.
What do the clinical trials show?
One Phase 3 clinical trial (NCT05085366) evaluated mRNA-1647 in 7,484 healthy participants aged 16 to 40 years. The study is completed. The main efficacy goal was to demonstrate that the vaccine prevents primary CMV infection in CMV-seronegative female participants, defined as seroconversion from negative to positive for serum IgG against at least one of four recombinant CMV antigens not encoded by mRNA-1647 (pp150, pp28, pp52, pp38). Safety and reactogenicity were also evaluated, including solicited adverse reactions through 7 days after each injection, unsolicited adverse events through 28 days after each injection, and serious adverse events from consent through end of study.
What side effects are known?
No side effect data from supplementary sources were provided for this page.