RSV-associated acute respiratory tract infections cause substantial morbidity, leading to the hospitalization of one in every 56 healthy term-born infants in high-income countries. Vaccination of pregnant women or healthy term-born infants during their first winter season could have a favorable effects on the health-care burden caused by RSV infections. These were the main conclusions by Roy Zuurbier from UMC Utrecht who defended his PhD thesis on June 1 2023.

In this PhD thesis, Roy Zuurbier (Department of Pediatric Infectious Diseases, UMC Utrecht) described the use of different point-of-care tests on respiratory syncytial virus (RSV) as well as the burden and dynamics of other respiratory viruses in infants, such as influenza virus and rhinovirus. The studies were performed within the prospective international ‘Respiratory Syncytial Virus Consortium in Europe’ (RESCEU) birth cohort and older adult cohort, and the Dutch ‘Microbiome Utrecht Infant Study’ (MUIS) birth cohort.

Key findings:

• Roy Zuurbier and colleagues found low sensitivity of the rapid antigen test BinaxNOW^® RSV for RSV detection in infants, with a sensitivity of only 7.6 percent. On the other hand, the performance of molecular-based Xpert^® Xpress Flu/RSV compared to routine RT-PCR was high for RSV detection in home-dwelling older adults.
• The investigators also examined the occurrence of respiratory viruses in infants during the first year of life. They found that rhinovirus (RV) was negatively associated with acute respiratory tract infection (ARTI). Asymptomatic RV in early life was, however, associated with increased susceptibility to and recurrence of ARTIs later in the first year of life.
• In the RESCEU study, in total 9,154 infants born between July 2017 and April 2020 were followed during the first year of life, of which 993 participated in the active part of the study. The incidence of hospitalizations due to RSV in the total cohort was 1.8 percent (95% CI 1.6-2.1). About half of the hospitalizations for respiratory tract infections in the first year of life were associated with RSV. The majority (57.9 percent) of hospitalizations due to RSV occurred in children under 3 months of age. The incidence of RSV infection and RSV infection under medical supervision in the active surveillance cohort was 26.2 percent (95% CI 24.0-28.6) and 14.1 percent (95% CI 12.3-16,0).
• In another analysis of the RESCEU study, Zuurbier found that RSV was responsible for the highest number of ARTIs in both non-hospitalized and hospitalized infants, especially during the first months of life. Incidence of influenza-related ARTI was low compared to RSV-related ARTI.

Zuurbier concluded that RSV-associated ARTI causes substantial morbidity, leading to the hospitalization of one in every 56 healthy term-born infants in high-income settings. Vaccination of pregnant women or healthy term-born infants during their first winter season could have a major effect on the health-care burden caused by RSV infections.

Respiratory tract infections

Respiratory tract infections (RTI) remain a major global health concern, being responsible for 15 percent of childhood deaths under the age of 5 years globally, and for considerable morbidity. Despite recognition of many host and environmental factors known to contribute to RTI susceptibility, such as age, gender, genetics, birth mode, breastfeeding, crowding conditions and environmental tobacco exposure, the exact mechanism(s) by which a child develops recurrent or severe RTIs while others remain healthy, has remained largely unknown.

PhD defense

Roy Zuurbier (1992, Hoorn) defended his PhD thesis on June 1, 2023 at Utrecht University. The title of his thesis was “Respiratory viruses in infancy and rapid RSV diagnostics.” Supervisor was prof. dr. Louis Bont (Department of Pediatric Infectious Diseases, UMC Utrecht). Co-supervisors were dr. Marlies van Houten (UMC Utrecht and Spaarne Gasthuis, Haarlem) and dr. Joanne Wildenbeest (Department of Pediatric Infectious Diseases, UMC Utrecht). In April 2023 Roy started as a paediatric resident (AIOS) at Amsterdam UMC.