Overview 

Respiratory syncytial virus (RSV) is common and can lead to mild cases of colds. Most people recover after a week or two, but RSV can be serious.

Babies and older adults are more likely to develop severe RSV and need hospital treatment, with severe cases of RSV being the leading cause of infant hospitalisation.

The United States experiences an annual occurrence of RSV  resulting in 58,000 to 80,000 hospitalisations for children under 5 years old.

RSV is spread through close contact with an infected person, through secretions from coughing and sneezing, or by touching objects such as toys or door knobs that have the virus on them.¹,²

Common underlying health conditions affected by RSV

To assess underlying health conditions that are associated with RSV an analysis of data looking back from January 2014 to December 2015 was performed. Each patient had nasopharyngeal swabs collected for laboratory analysis. In total, 1346 diagnostic samples were analyzed. 

RSV was mainly observed in children, accounting for 41% of cases. Men were more impacted than women, with a majority of 61% affected. The median (middle) age was 1 year old (ranging from 0.5 to 94.0). The average duration of hospital stay was 6 days. Chronic cardiovascular disease was the most frequently reported preexisting condition, yet 67% of individuals did not have any documented underlying illness. Hospital admissions for Severe Acute Respiratory Infections (SARI) were often linked to respiratory viruses, notably RSV, adenovirus, and influenza.³

A systematic review was conducted to identify articles released from 2003 to 2023, focusing on the epidemiological or economic effects of RSV. The review revealed that RSV leads to substantial sickness among infants, young kids, and the elderly in Germany, particularly affecting infants. There has not been much research done on how RSV infection impacts healthy children and the elderly in Germany. Given the high burden reported in studies, more focus should be placed on the medical and economic effects of RSV in these populations.⁴

The following conditions have been shown to be affected by RSV:

Chronic lung diseases

• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Cystic fibrosis
• Bronchiectasis
• Idiopathic pulmonary fibrosis (IPF)

Heart diseases

1. Congestive heart failure (CHF)
2. Coronary artery disease (CAD)
3. Cardiomyopathy
4. Heart valve disease

Immune system disorders

1. HIV/AIDS
2. Cancer
3. Organ transplant recipients, who must take immunosuppressant medication

Other chronic conditions

1. Diabetes
2. Kidney disease
3. Liver disease

Impact of RSV on individuals with underlying health conditions

Up to 160,000 adults are hospitalised annually in the United States due to the worsening of RSV cases. In more severe cases, RSV has a strong impact on heart health. About 14 to 22% of adult hospital admissions are complicated by: 

1. Cardiovascular disease, including worsening heart failure, acute coronary syndrome and arrhythmias. Cardiovascular disease has also been associated with 45-63% of RSV hospitalisations in adults. 
2. Deterioration of existing conditions such as asthma or COPD. 
3. Medications or other health problems that weaken your immune system.
4. Those who have undergone a bone marrow transplant are at the highest risk of serious illness in adults with compromised immune systems.^5,6

Children with epilepsy who develop RSV experience more severe illnesses, leading to increased utilisation of resources. The significance of protecting susceptible children from infection is emphasised through hygiene, proper isolation, and vaccination strategies. When contemplating universal vaccination, such as for rotavirus vaccines, assessing a vaccination program should consider the potential benefits for susceptible children.⁷

Precautions and preventive measures for individuals with underlying health conditions

To develop and plan preventative measures it is crucial to understand the chain of infection. The chain contains 6 links: pathogen, reservoir, port of departure, means of transmission, portal of entry, and susceptible host.

A pathogen is a microorganism or bacterium that causes disease.

Transmission is the way pathogens are transferred from one person or place to another.

The portal of entry is the portal where pathogens enter the body.

By taking a prescribed antibiotic regimen, the risk of pathogen resistance to treatment is reduced, as demonstrated in chain break links. 

To prevent the entry of pathogens through mucous membranes, Liquid-repellent surgical face masks and eye protection are used as a portal of entry for patients.⁸

Vaccination

Niresevimab is an injectable monoclonal antibody, used for the prevention of RSV infection. A nationwide study was conducted, which matched cases and controls to evaluate how well nirsevimab treatment works in preventing hospitalisation for RSV-related bronchiolitis in infants under 12 months old. Infants younger than 12 months old who were hospitalised for RSV-related bronchiolitis between October 15 and December 10, 2023 were considered as case patients. The control group consisted of infants who visited the same hospitals for non-RSV related conditions. The effectiveness of nirsevimab in preventing hospitalisation for RSV-associated bronchiolitis was determined using a multivariate conditional logistic regression model, adjusting for confounding factors. A number of sensitivity analyses were conducted.

The study found that nirsevimab treatment effectively decreased the likelihood of RSV-associated bronchiolitis requiring hospitalisation.⁹ 

A study analysing data from 2012 to 2022 was carried out at the Affiliated Children's Hospital of Chongqing Medical University. This showed that there was a significant link discovered between the age at RSV infection and the time from birth to the peak RSV season. Babies born during the RSV outbreak season were more likely to get infected in the first 2 months after birth. On the other hand, individuals who were not born during the RSV epidemic season had a higher risk of getting infected during the following peak. Age and timing of infection were the main factors contributing to severe RSV infection in infants with preexisting conditions. The timing of RSV infection in infants varied initially based on their health condition. Youth and the timing of infection during the RSV outbreak were important factors for severe RSV infection. These results offer a theoretical foundation for improving vaccination tactics for babies with various health issues. 

Severe RSV disease is prevented by a single dose of the RSP vaccine for adults aged 60 and above. The best time for vaccination is in late summer or early autumn, just before RSV usually starts to spread. 

Prevention in babies

There are two ways to protect your baby from RSV infection.

• The RSV vaccine administered during pregnancy at 32 to 36 weeks, ensures the safety of your child, and you won't need to use it again for an additional year.

In rare cases, the healthcare provider may decide that the baby needs the RSV vaccine after birth, even if the mother has received the RSV vaccine.

• Children aged 8 to 19 months who are entering their second RSV season and belong to one of the following groups: children with severe immunodeficiency, premature birth, or chronic lung disease, may also be screened for antibodies that can prevent the spread of RSV by treating all cases of.^10,11

Summary

RSV-related adverse effects may affect people with health problems, resulting in up to 160,000 adults being hospitalised annually in the United States.

In more severe cases, RSV has a strong impact on heart health. Between 45 and 63 per cent of adults hospitalised with RSV is due to cardiovascular disease.

A single dose of the RSP vaccine for adults 60 years of age or older prevents severe RSV disease.

To prevent the spread of RSV infection, two methods can be used to protect babies and toddlers using RSP vaccines. Even if the mother has been vaccinated during pregnancy, it is possible that the healthcare provider may still decide to administer the vaccine to the infant.