Studies under leadership of the RSV Research Group at UMC Utrecht show that infection with the respiratory syncytial virus (RSV) is also prevalent in older adults, with an overall prevalence of 5.7 percent in Europe. In contrast to infants, the infection rarely causes severe disease in home-dwelling adults ≥60 years. Nevertheless, a watchful waiting approach to identify patients that are at risk of severe disease is justified when RSV is the suspected pathogen.

Respiratory syncytial virus (RSV) is best known for the - sometimes severe - acute respiratory tract infections (ARTI) that this virus may cause in infants. Occasionally, hospitalization or even intensive care unit admission is necessary. Mortality in high-income countries is rare, but the burden of RSV in low-income countries is enormous with an estimated 60.000 in-hospital deaths in children <5 years of age. In elderly people, RSV infections are usually milder than primary childhood infections, but due to increased frailty because of immunosenescence and comorbidity RSV can still cause severe ARTI and mortality in at-risk patients (for example in those with COPD).

Although RSV illness in older adults is recognized as an important health issue, the burden of disease outside the hospital and nursing homes is largely unknown. Therefore, PhD student Koos Korsten (Department of Pediatric Infectious Diseases and Immunology, Wilhelmina Children's Hospital/UMC Utrecht) assessed the burden of RSV illness in older adults living in the community using data from the REspiratory Syncytial virus Consortium in EUrope (RESCEU) study.

Burden of RSV illness

In an observational cohort study conducted in Antwerp (Belgium), Utrecht (the Netherlands) and Oxford (United Kingdom), recently published in the European Respiratory Journal, 1,040 participants aged ≥60 years were recruited from GP offices during two RSV seasons (527 in season 2017-2018, 513 in season 2018-2019). The median age was 75 years and almost all were living independently at home. The average incidence of RSV-illness in this relatively healthy cohort during the two seasons was 5.7 percent. Most infections were mild and no patients were hospitalized or died from RSV-illness. In the 36 patients with PCR-confirmed ARTI due to RSV (RSV-ARTI), the average duration of symptoms was 19 days, while a doctor’s visit took place in 31 percent of cases. In addition, RSV-ARTI could not clinically be differentiated from other ARTI (such as influenza) based on clinical symptoms.

Koos Korsten concludes: “Our study in older community-dwelling adults shows that RSV illness is prevalent but rarely causes severe disease. This suggests that watchful waiting using a continuity of care approach to identify those who do need more intensive care is often justified when RSV is suspected in family practice.”

Role of children

Another interesting finding in the RESCEU study by Koos Korsten and co-investigators was that exposure of older adults to children <5 years was associated with an increased risk (Odds ratio 1.58, 95% CI 1.28-2.08, p=0.001) of all-cause ARTI (including influenza, RSV and other pathogens). Although this increased risk may also apply to RSV, the study was not powered to investigate the relationship between child exposure and RSV infection. The risk of all-cause ARTI was highest in those with the most frequent contact (for example grandparents babysitting their grandchildren). It was estimated that approximately 10 percent of all ARTI in elderly people can be attributed to exposure to preschool children.

“While restricting contact between young children and elderly people might be feasible in an epidemic situation or in very frail patients, there are obvious social and economic issues involved with sustaining such measures. Therefore, pediatric vaccination for respiratory pathogens may be an interesting option to indirectly decrease ARTI burden in older adults”, concludes Koos Korsten.

The RESCEU project

The RSV Research Group at UMC Utrecht is the work package lead for the prospective clinical cohort studies in RESCEU. RESCEU aims to develop robust evidence on RSV disease burden and economic impact; create a sustainable Europe-wide multidisciplinary, multi-stakeholder community from academia, public health, scientific societies, patient organisations, regulatory agencies and industry; and provide an infrastructure to perform future pivotal trials for RSV vaccines and therapeutics. RESCEU has received funding from the Innovative Medicines Initiative 2 Joint Undertaking under grant agreement Nº 116019. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation program and the European Federation of Pharmaceutical Industries and Associations (EFPIA). For more info, visit www.resc-eu.org.

PhD defense

Koos Korsten (1989, Utrecht) will defend his PhD thesis on April 1, 2021 at Utrecht University. The title of his thesis is “Respiratory syncytial virus infections on both ends of the age spectrum”. Supervisor is prof. dr. Louis Bont and co-supervisor is dr. Joanne Wildenbeest (both Department of Pediatric Infectious Diseases and Immunology, Wilhelmina Children's Hospital/UMC Utrecht). In 2020 Koos Korsten started working as an ANIOS in pediatrics at the Gelderse Vallei Hospital in Ede.