Background Viral interference is the concept that different viruses have an effect on the incidence of other viruses– either positive or negative. While this has been demonstrated in vitro and in animal models, it is not well described in large observational studies. Methods We analysed all patients tested for positive respiratory viruses between January 2016– December 2019 just prior to the pandemic in the National University Hospital laboratory, Singapore. Nasal, throat, and/ or nasopharyngeal swabs were collected by treating clinicians and tested by either multiplex PCR or immunofluorescence. Survival plots were created to study the time for a second viral infection following the initial respiratory viral detection. Results RSV (HR: 0.63, 95%CI: 0.43–0.92; p<0.01) and influenza (HR: 0.41, 95%CI: 0.27-0.61; p<0.001) -positive cases showed a greater delay in subsequent respiratory infections compared to other pathogens, suggesting relative protection, while enterovirus/ rhinovirus (HR: 2.05, 95%CI: 1.52-2.77; p<0.001) and Parainfluenza (HR: 1.76, 95%CI: 1.18-2.63; p<0.001) showed heightened susceptibility. No significant associations were found for Adenovirus, seasonal coronaviruses, and other pathogens. Conclusion We found that it is possible that prior infections with Influenza virus or RSV conferred significant cross-protection against subsequent circulating respiratory viral infections for the next 4 years. Larger studies are needed to explore mechanisms behind this possible broad-spectrum antiviral response in human hosts as this may have implications for vaccination strategies.