Severe respiratory infections in children

A child with a respiratory infection may spend a few days being treated on a general ward. But when the condition worsens and requires intensive care, nearly the entire scope of the hospital stay changes: care becomes more complex, more resources are needed and the impact on the child’s health increases.

A study published in The Lancet Regional Health – Americas helps measure that difference. The researchers followed 747 children under 5 years old hospitalized with severe lower respiratory tract infection at centers in Argentina, Brazil and Colombia. Respiratory syncytial virus (RSV) was identified in 49% of participants. At the Brazilian center, 56% of the children had RSV and, among the RSV-positive children, 42% were admitted to the ICU.

The frequency of the virus, however, tells only part of the story.

When the researchers analyzed what weighed most on costs and health loss, the main difference did not simply appear between having or not having RSV. It appeared between staying on the ward and needing the ICU.

Hospitalizations in intensive care had substantially higher costs. At the same time, differences in total cost between RSV-positive and RSV-negative children were not statistically significant at any of the three centers.

Infectious disease specialist Fabrício Carvalho, of Einstein Hospital Israelita, who reviewed the results as an independent expert for Prime Health Report, highlights this distinction.

“The greatest burden, both for the child’s health and in terms of cost, lies not in the mere presence of the virus, but in the severity of the illness.”

Carvalho also makes an essential caveat: these are data from children who were already hospitalized at specific centers and therefore should not be generalized to the entire pediatric population.

At the Brazilian hospital, more than half had RSV

The Brazilian center enrolled 294 children, of whom 166 (56%) had confirmed RSV. Among the RSV-positive children, 69 of 166 (42%) were admitted to the ICU. Among the RSV-negative children, it was 35 of 128 (27%). The difference was statistically significant.

The number is striking, but it does not mean that 42% of Brazilian children with RSV need intensive care.

The population served by the Brazilian center had particular characteristics. Among RSV-positive children, the median age was just 5 months, while at the Argentine and Colombian centers it reached 17 and 18 months, respectively.

For Luiz Vicente Ribeiro, the study’s Brazilian author, associate professor (livre-docente) in the Department of Pediatrics at FMUSP (University of São Paulo Medical School) and pulmonologist at the Instituto da Criança e do Adolescente, the age profile helps explain the result.

“Younger children are at greater risk of hospital admission for lower respiratory tract infections.”

He also points to the dynamics of HU-USP (the University of São Paulo’s University Hospital), which receives cases referred for admission by urgent care units (Unidades de Pronto Atendimento). The combination of younger patients who had already been selected for hospital care may contribute to the high ICU rate observed at the center.

Why babies are more vulnerable

The young age of the Brazilian patients has an important clinical explanation.

According to Carvalho, babies’ greater vulnerability results from a combination of anatomical, immunological and physiological factors.

Their airways are proportionally very narrow. When an infection causes inflammation and increases the production of secretions, the reduction in space available for air to pass through can have a much greater impact on a baby than on an older child or adult.

There is also the maturation of the immune system, which is still developing in the first months of life. Children with certain heart or lung diseases may have additional vulnerability.

The third component is what the infectious disease specialist calls physiological reserve — the body’s ability to keep functioning in the face of illness.

“Babies and young children have a smaller physiological reserve. That means they tire more quickly.”

As the work of breathing increases, the muscles can become fatigued. The baby may reach a point where it has difficulty both breathing and feeding at the same time.

When a respiratory infection becomes a concern

Most pediatric respiratory infections, according to Carvalho, are mild and can be monitored at home. In general, the child remains in good overall condition, stays active and is able to breastfeed or eat. The picture changes when signs of breathing effort or significant deterioration in overall condition appear.

Very rapid breathing and respiratory effort — noticeable, for example, when the ribs become more visible during breathing — are among the signs described by the infectious disease specialist. Difficulty breastfeeding or taking in fluids, a significant change in level of alertness and, in young babies, pauses in breathing also warrant attention.

“If any of these signs appear, it is essential to seek care without delay,” says Carvalho.

For the infectious disease specialist, the assessment does not depend solely on identifying the virus: the clinical examination and the child’s condition are central to determining severity.

When the hospital stay reaches the ICU, costs change in scale

The economic difference becomes clearer when the researchers place the ward and intensive care side by side.

Among children with RSV treated at the Brazilian center, the estimated mean societal cost of a ward episode was approximately US$959. In the ICU, it reached US$3,770 — almost four times as much.

But there is a crucial detail: among children who did not have RSV, the pattern was similar. The mean cost went from US$885 on the ward to US$3,639 in the ICU.

The pattern found in the study was consistent: ICU admission was the main driver of costs, with a several-fold increase compared with the ward regardless of RSV status.

When the researchers directly compared RSV-positive and RSV-negative children, they found no statistically significant difference in total cost at any of the three hospitals.

Thus, the study does not show that a hospitalization for RSV is necessarily more expensive than a hospitalization for another severe respiratory infection.

What substantially changes the economic scale is the need for intensive care.

What changes when a child reaches the ICU

Carvalho’s clinical explanation helps clarify what lies behind this economic jump.

On a ward, he says, care may involve oxygen, hydration, observation and physical therapy. In intensive care are children who may not be able to adequately maintain respiratory function on their own.

In these cases, support may progress to positive-pressure devices and, in the most severe situations, orotracheal intubation and mechanical ventilation, while the lungs recover.

The level of monitoring also changes. The child is continuously monitored by a multidisciplinary team because, in critical cases, the condition can change rapidly.

“The ICU concentrates more technology and more specialized professionals.”

This intensity of care helps explain why severe cases weigh so heavily on the child’s health and on hospital resources.

Measuring the real cost in the SUS (Brazil’s public health system) was a challenge

The economic figures presented in the study are estimates constructed to allow comparison across countries. They do not correspond to the nominal amount paid by the SUS and should not be converted directly into reais as if they represented the price of a hospital stay.

There is an additional difficulty in the Brazilian case.

Silva Filho explains that reconstructing the real costs of care in the SUS was one of the methodological challenges the researchers faced.

“The SUS’s tripartite funding and its unrealistic reimbursement, below true costs, made the task of assessing real costs a challenge for the authors.”

According to him, for some components it was necessary to rely on information from other public hospitals.

“We had to extrapolate some hospital and ICU daily costs from other SUS hospitals with more consistent information.”

This point reinforces a limitation acknowledged in the research: the Brazilian figures may underestimate part of the costs actually involved in care.

For Silva Filho, the difficulty of knowing real costs may also affect public policy decisions, including assessments related to the adoption of new technologies.

This is the researcher’s interpretation, not an economic result directly tested by the study.

Why does the ICU weigh so much?

The researchers tracked the resources used by each patient and considered hospitalization, respiratory support, medications and other components of care.

Days of hospitalization were the largest component of direct medical costs.

At the Brazilian center, they accounted for approximately 80% of these costs on the ward and 71% in the ICU.

But the bill does not end at the hospital.

The research also considered transportation, food, lodging and other expenses related to accompanying the child, as well as caregivers’ lost productivity.

These amounts represented a smaller share of the total cost, but they reveal a dimension that hospital figures do not always capture: when a child is hospitalized, the family’s routine and budget are also affected.

The impact also shows up in the child’s health

The researchers also used a measure called DALY, or disability-adjusted life years. It estimates the burden of a disease by accounting for periods lived with impaired health and years lost to premature death.

At the Brazilian center, among children with RSV, the median was approximately 0.0011 DALY on the ward and 0.0035 in the ICU.

The pattern of greater burden among patients who needed intensive care also appeared at the other centers.

Costs and health loss, therefore, pointed in the same direction: the episodes that reached the ICU concentrated the greatest impact.

Mortality within the cohort was rare. Among the 747 children analyzed, there was only one in-hospital death, which occurred in a child without RSV at the Brazilian center.

This result does not allow the conclusion that RSV-associated mortality is negligible outside the population studied.

If RSV alone doesn’t explain the costs, why does it matter?

Because frequency, severity and individual cost are different dimensions.

RSV appeared in nearly half of the hospitalized children evaluated in the study. At the Brazilian center, it was present in more than half.

At the same time, at that hospital, RSV-positive children had a higher rate of ICU admission than RSV-negative children.

This separates two questions.

The first is: what share of the severe respiratory infections that lead to children’s hospitalization is due to RSV?

The second: what makes each episode generate a greater economic and health burden?

For the second question, the results point mainly to severity and to the intensity of care required.

The independent assessment converges on this point: Carvalho notes that cases requiring intensive care concentrate greater resource use because they come to require advanced support, continuous monitoring and specialized teams.

RSV prevention: what can the study conclude?

The article mentions strategies such as vaccination during pregnancy and long-acting monoclonal antibodies. The authors argue that prospective estimates of the hospital burden can provide input for future economic and budget-impact evaluations of RSV prevention strategies.

Silva Filho believes that adopting strategies to prevent severe RSV infections could meaningfully change the clinical and economic burden in the country.

This statement, however, should be understood as the researcher’s technical expectation, not as a result demonstrated by the study.

The research did not test these interventions, did not calculate their cost-effectiveness and did not demonstrate how much they could reduce ICU admissions or hospital spending in Brazil.

The scientific frontier therefore remains: demonstrating how much of the hospital burden can be prevented by a specific preventive strategy requires evidence specific to that intervention and population.

One hospital is not Brazil

This remains one of the main cautions in interpreting the results.

Although it involved three countries, the research was conducted at only one tertiary referral hospital in each country. The article itself states explicitly that the data from the participating centers are not nationally representative.

Silva Filho considers it plausible that a similar scenario would be found at other SUS hospitals that treat children with acute respiratory infections, but adds that ICU admission rates may also be influenced by bed availability.

Carvalho offers a complementary counterpoint: in interpreting the data, he stresses that these are children already hospitalized at specific centers and that the numbers should not be automatically extended to the entire population.

The two observations are not incompatible.

The first is the author’s clinical assessment of what may happen at other public hospitals. The second sets the methodological boundary of the available evidence.

For this reason, the numbers found at the Brazilian center should not be treated as national estimates.

Severity is the turning point

The results make it possible to view the burden of severe respiratory infections in childhood from complementary perspectives.

RSV appeared in 49% of the hospitalized children analyzed and in 56% of participants at the Brazilian center. At that hospital, children with the virus also had a higher rate of ICU admission.

But when the researchers analyzed costs and health loss, it was the need for intensive care that marked the main difference.

The contributions of the two physicians help explain what lies behind these numbers.

Silva Filho puts into context the particularities of the Brazilian population and the difficulties of measuring real costs within the SUS structure.

Carvalho explains the clinical trajectory: why babies are more vulnerable, which changes signal worsening and why reaching the ICU represents a substantial shift in the intensity of care.

The question, therefore, is not simply how much RSV costs.

It is understanding how much of the burden of severe respiratory infections is concentrated precisely in the episodes that progress to greater severity — and how much of that burden may be prevented in the future.

This study begins to answer the first part. The second still depends on future evidence.

Scientific transparency

The study was supported by the Merck Investigator Studies Program (MISP-58738). According to the article, the sponsor did not participate in the study design, data collection, analysis or interpretation, writing of the paper or the decision to submit it for publication. The article also includes the authors’ individual declarations of potential conflicts of interest.

Scientific references

Guiñazú GG, Dvorkin J, Sorgente P, et al. Economic and health burden of severe respiratory syncytial virus infection among hospitalised children at three tertiary hospitals in Argentina, Brazil, and Colombia: a two-year prospective multicentre cohort study. The Lancet Regional Health – Americas. 2026;63:101601. DOI: 10.1016/j.lana.2026.101601.

Hammitt LL, Dagan R, Yuan Y, et al. Nirsevimab for prevention of RSV in healthy late-preterm and term infants. New England Journal of Medicine. 2022;386:837–846.

Kampmann B, Madhi SA, Munjal I, et al. Bivalent prefusion F vaccine in pregnancy to prevent RSV illness in infants. New England Journal of Medicine. 2023;388:1451–1464.

Zar HJ, Simões EAF, Madhi SA, et al. Clesrovimab for prevention of RSV disease in healthy infants. New England Journal of Medicine. 2025;393:1292–1303.

Pecenka C, Sparrow E, Feikin DR, et al. Respiratory syncytial virus vaccination and immunoprophylaxis: realising the potential for protection of young children. The Lancet. 2024. DOI: 10.1016/S0140-6736(24)01699-4.