Background: Respiratory syncytial virus (RSV) is a major pathogen that causes respiratory illness in adults and most commonly affects populations with additional comorbidities or the elderly. RSV poses a significant risk for severe respiratory infections among adults. The mRNA-1345 vaccine utilizes advanced mRNA technology. While mRNA vaccines have demonstrated considerable success in other infectious disease contexts, detailed evidence on the efficacy, safety, and immunogenicity of mRNA-1345 specifically for RSV among adults remains scarce. Objective: We aimed to evaluate the effectiveness and safety profile of the mRNA-1345 vaccine in preventing RSV infections in adult populations. Method: A search was conducted through PubMed and the Cochrane Library to identify randomized controlled trials examining the efficacy and safety of the mRNA-1345 vaccine against RSV. The review was conducted adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: The mRNA-1345 vaccine demonstrated an overall efficacy of 68.4% against RSV- associated respiratory illness (ARI) and 83.7% against RSV-associated lower-respiratory-tract disease (LRTD) with at least two signs or symptoms in individuals aged 60 and older. Concerning RSV-associated respiratory illness (ARI), the vaccine provided 78.5% protection against RSV-A and 51.7% against RSV-B strains. The vaccine's safety profile was comparable to a placebo, with mild to moderate adverse events like injection-site pain and fever. Adverse events were rare and equally distributed between the vaccine and placebo groups. Conclusion: The mRNA-1345 vaccine has demonstrated significant benefits in preventing RSV-associated LRTD and ARI in adults aged 60 and older. Additionally, it has proven to have an acceptable safety profile across age groups, particularly in those aged 18-49 and 60 and above. The vaccine also elicited a robust immune response, with clear evidence of immunogenicity. Overall, the mRNA-1345 vaccine emerges as a promising candidate for adult vaccination.