Respiratory syncytial virus (RSV) infection is a relatively common respiratory viral infection that primarily causes acute bronchiolitis in infants and is known to lead to long-term respiratory complications.

Recently, it has become increasingly clear that this virus can also cause serious respiratory complications in older adults with various underlying conditions. As a result, leading multinational pharmaceutical companies worldwide are accelerating vaccine development research to prevent RSV infection. However, to date there have been no specific studies on the long-term complications of RSV infection, including its impact on the severity of subsequent COVID-19 infection.

A research team led by Jeonbuk National University (JBNU) Distinguished Professor 이용철 (Department of Respiratory and Allergy Medicine, School of Medicine) and Professor 정재석 (Institute for Molecular Biology and Genetics), in collaboration with Professor 김종승 of the Department of Medical Informatics, School of Medicine, reported that RSV infection can lead to more severe outcomes when patients subsequently contract COVID-19.

The research team confirmed a significant increase in the severity of COVID-19 cases occurring during the pandemic among individuals with prior RSV infection compared with matched controls without prior RSV infection. They published these findings in the latest issue of the international journal Allergy (impact factor 12.4).

Using the National Health Insurance Service sample cohort database — the largest to date, containing about 8.6 million people — the team selected approximately 18,000 individuals who had been infected with RSV within the three years immediately preceding the COVID-19 pandemic (2017–2019). They conducted a comparative analysis against an equally sized control group matched on age, sex, residential area, socioeconomic status, and underlying conditions.

They found that prior RSV infection was associated with a significant increase in the incidence of COVID-19. In an additional analysis of approximately 570,000 COVID-19 patients within the sample cohort, the researchers observed a significant increase in COVID-19–related hospitalizations and severe COVID-19 among those with prior RSV infection. The increase in severe COVID-19 was particularly pronounced in individuals who had an RSV infection in the year immediately preceding the pandemic.

The study's results were well received by the academic community. They suggest the potential benefit that RSV vaccines — whose preventive efficacy in older adults with various underlying conditions has recently been demonstrated in large international clinical trials — may also positively influence the clinical course of other secondary respiratory viral infections in adults without specific underlying diseases.

The research team led by Distinguished Professor 이용철 (Department of Respiratory and Allergy Medicine, JBNU School of Medicine) and Professor 정재석 (Institute for Molecular Biology and Genetics) has long conducted state-funded research into the pathogenesis and therapeutic development for chronic lung disease, earning international recognition for their expertise. Recently, they established the country’s first "Airway-Targeted Therapeutics Development Institute" and are actively pursuing the development of inhaled airway-targeted new drugs and vaccines to prevent and treat secondary respiratory infections. They are carrying out this work through collaboration with specialists across disciplines and by coordinating with various large-scale national research projects.

Meanwhile, the study listed respiratory and allergy specialist 이환진 of Jeonbuk National University Hospital as the first author. It was conducted with support from the Biomedical Research Institute of Jeonbuk National University Hospital — designated in 2023 by the Ministry of Science and ICT as the "Innovative Future Medical Research Center" for the Gwangju·Jeonnam·Jeonbuk·Jeju region — under Principal Investigator (PI) 고명환 and supporting researcher 정재석.