Among older adults in Spain, hospitalisation rates from respiratory syncytial virus (RSV) infection increases progressively with age and is more likely among people with other health issues and who live in nursing homes, according to a study published in Eurosurveillance. The hospitalisation rate varied considerably with age and the presence of risk conditions, with important implications for possible targeted interventions.
This population-based cohort study analysed patient data for adults over the age of 60 years in seasons 2016/17 to 2019/20 obtained through electronic medical records from the region of Navarre in Spain, with RSV hospitalisations being confirmed with PCR testing. The average annual incidence rate of RSV hospitalisation was calculated for the pool of the four study periods by dividing the total number of cases by the sum of the study population at the beginning of each period. The hospitalisation rate for each socio-demographic and risk condition was analysed using Poisson regression.
Higher hospitalisation rates with age and presence of risk conditions
On average over four seasons, the study found that RSV caused 84.7 hospitalisations per 100,000 among people older than 60 years, and varied significantly depending on age and certain risk factors.
The likelihood of hospitalisation was strongly associated with increased age. Compared with people aged 60–64 years, the rate increased 2-, 3-, 4- and 6- fold in people older than 70, 75, 80 and 85 years, respectively. It reached the highest rate among those aged 85─94, with more than 200 RSV hospitalisations per 100,000 people in this group. This increased risk might be explained by the gradual decline of the immune system related to aging.
Higher hospitalisation rates were associated with several chronic conditions, possibly due to a higher likelihood of infection and increased severity of RSV disease. Blood cancer was the chronic condition that increased the risk of hospitalisation the most, multiplying it by a factor of 3.8. Chronic obstructive pulmonary disease (COPD) was also an important risk factor. The most common chronic condition in patients was cardiovascular disease, which doubled the risk of hospitalisation for people infected with RSV.
Other conditions associated with higher rates of RSV hospitalisation were functional dependence, asthma, severe obesity, diabetes and chronic kidney disease. People living in nursing homes were twice as likely as those with similar traits who did not live in these facilities to be hospitalised, which could be due to close contact with caregivers and other vulnerable people.
Targeted public health action could significantly reduce hospitalisation rates
Based on the results, the authors recommend that non-pharmacological preventive measures be strengthened for the adults identified to be at the highest risk in this study, and that they be considered a priority target population for RSV vaccination.
As their rates of hospitalisation are very high (>0.3%), these include people 60 years and older with haematological cancer or nursing home residence, people older than 74 years with COPD or functional dependence, and people older than 84 years with asthma or cardiovascular disease.
Based on the Navarre data, considering these risk groups as target groups would involve immunising only 13% of people aged 60 years and older, but would address half of RSV hospitalisations in this age group, and could substantially reduce the burden of RSV on healthcare systems and RSV-related deaths.
