Understanding the Burden of RSV Infections in Adults: Insights from the 11th Congress on the Frailty of the Elderly

2023-07-04 21:16:21

During the 11th congress on the frailty of the elderly subject, Prof. Elisabeth Bothelo-Nevers, from the infectiology department of the CHU of Saint-Etienne, takes stock of the burden of respiratory syncytial virus (RSV) infections in adults and in particular in the elderly. Beyond the respiratory complications common to other viruses, it is the extra-respiratory complications that should be prevented by identifying the virus.

RSV is an enveloped single-stranded RNA virus belonging to the family Pneumoviridae. Bronchiolitis virus, it can be responsible for severe respiratory infections in children up to 5 years old. Infections do not provide persistent immunity, hence the risk of regular reinfection throughout life.

RSV circulates seasonally in winter, with a peak from November to January, in frequent co-circulation with the influenza virus (with a slight phase advance). While infections had decreased during the confinement periods in 2020 and 2021, a very large epidemic took place this year (2022-2023 season), in the context of a triple Flu/COVID/RSV epidemic. The systematic search for RSV by PCR, at the same time as that for SARS-CoV-2 and the influenza virus, has only been systematic for 1 year. We therefore only have a few data on the circulation of this virus in adults, but we now know that its burden is clearly underestimated and that the damage is not the same as in children.

Which adults are most affected?

American studies have shown that hospitalizations related to an RSV infection were more frequent in subjects over 65 years of age (risk multiplied by 8 versus under 65) and immunocompromised subjects (risk multiplied by 5 versus immunocompetent subjects) (1). The risk of hospitalization is also higher in subjects suffering from COPD, heart failure or chronic renal or neurological pathologies (2). It is also particularly important in immunocompromised subjects, especially those who have received a hematopoietic stem cell transplant. In this population, infection of the upper respiratory tract frequently progresses to low infection (40 to 60% of cases), leading to death in more than 80% of cases. An increased risk of hospitalization related to this infection has also been observed in subjects with hematological malignancies and solid cancers, or in those on immunosuppressive therapy (3,4). As expected, the risks are cumulative, and the incidence rates of hospitalization related to RSV infection increase in elderly subjects with comorbidities (5).

The respiratory burden of RSV in the elderly

In practice, RSV infection is symptomatic in 90% of cases, whereas asymptomatic forms are more numerous for other respiratory viruses. In the elderly, it generally presents with signs of upper respiratory infection accompanied by general signs (asthenia, fever, anorexia). Signs of low infection appear following 3 or 4 days. And it is clinically very difficult to distinguish an RSV infection from another respiratory infection of viral origin (influenza or other), hence the interest of a PCR diagnosis.

A recent meta-analysis carried out in elderly subjects in Europe between 2000 and 2019 showed that RSV was responsible for 5% to 7.8% of symptomatic respiratory infections in elderly adults (>60 years), with a mortality of regarding 8%, up to 10% in adults (>18 years) with comorbidities (6).

In France, the PMSI data – those for which the pathology was really coded as an RSV infection, which is rarely possible in practice since it is rarely searched for – show that between 2007 and 2020, approximately 13,000 patients were hospitalized for RSV infection. The average age was 74 years and 80% of patients had at least one comorbidity. The average lengths of stay were quite long (12 days). Eleven percent of patients required admission to intensive care, 7% died, and 30% had to be rehospitalized within 3 months. An age greater than or equal to 60 years and the presence of a co-infection, in particular bacterial, were associated with a more severe evolution (7).

Underestimated extra-respiratory consequences

Beyond the expected respiratory burden, there are also less known non-infectious complications such as myocardial infarction, cardiovascular accidents, decompensation of comorbidities (diabetes, heart failure, COPD), and loss of autonomy. . The risk of myocardial infarction, for example, is multiplied by 3.5 within 7 days of RSV infection. This figure is to be compared with a risk multiplied by 6 for the flu and by 2.8 for other viruses (8). The lengths of hospital stay are longer than for the flu (8 days vs 6j) and mortality is not negligible (9). More worryingly, 6 months following an RSV infection, more than a third of patients have not recovered their functional level and have even worsened compared to their pre-infection state (10). Added to all this is the disorganization of the healthcare system, which is felt more in the event of a multiple epidemic like this year (flu, RSV, COVID).

These results show that these RSV infections, which often go unnoticed because they are not virologically diagnosed, actually have a very significant public health impact, similar to that of influenza in terms of hospitalization and death. This should encourage health professionals to expand the use of PCR in order to identify these infections more systematically.

Prevention solutions for the future

Several vaccine candidates are under development. Two have already obtained marketing authorization in the United States. That of the Glaxosmithkline laboratory (GSK) has just obtained its own in Europe. It is an adjuvanted vaccine which has shown its effectiveness in the prevention of RSV infections in subjects over 60 years of age, with good tolerance (11). It should make it possible to quickly propose a preventive approach to these infections to the target populations, and probably also to prevent the associated extra-respiratory events. It remains to convince the patients, which will require informing and communicating as was done for pneumococcal infections.

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