Respiratory Syncytial Virus: Seasonal Data for Regions of Florida and Implications for Palivizumab

Global Seasonal Activities of Respiratory Syncytial Virus Before the Coronavirus Disease 2019 Pandemic: A Systematic Review

Varied seasonal patterns of respiratory syncytial virus (RSV) have been reported worldwide. We conducted a systematic review on articles identified in PubMed reporting RSV seasonality based on data collected before 1 January 2020. RSV seasonal patterns were examined by geographic location, calendar month, analytic method, and meteorological factors including temperature and absolute humidity. Correlation and regression analyses were conducted to explore the relationship between RSV seasonality and study methods and characteristics of study locations. RSV seasons were reported in 209 articles published in 1973-2023 for 317 locations in 77 countries. Regular RSV seasons were similarly reported in countries in temperate regions, with highly variable seasons identified in subtropical and tropical countries. Longer durations of RSV seasons were associated with a higher daily average mean temperature and daily average mean absolute humidity. The global seasonal patterns of RSV provided important information for optimizing interventions against RSV infection.

Respiratory syncytial virus seasonality and its implications on prevention strategies

With maternal and infant vaccines against respiratory syncytial virus (RSV) in development, it is timely to consider how the deployment of these vaccines might vary according to local RSV disease seasonality. In temperate regions RSV infection is predictably limited to a period of 3 to 5 months, while in tropical regions disease seasonality is often both more variable and more prolonged. Accordingly, in tropical regions a year-round immunisation schedule for both maternal and infant immunisation might be appropriate. In contrast, in temperate regions the benefit of year-round maternal immunisation would be heavily dependent on the duration of protection this provided, potentially necessitating a strategy directed at children due to be born in the months immediately prior to the RSV season. This review will consider the impact of seasonality on maternal and infant immunisation strategies against RSV, and the potential of an alternative approach of passive immunisation for all infants immediately prior to the RSV season.

Prevalence of respiratory syncytial virus-associated lower respiratory infection and apnea in infants presenting to the emergency department

The prevalence of respiratory syncytial virus in children presenting to US emergency departments with lower respiratory tract infection or apnea (N = 4172) was evaluated outside the traditional respiratory syncytial virus season (September to October and April to May) relative to January to February. The Mid-Atlantic and Southeast demonstrated positivity rates in September to October comparable with rates observed during January to February.

Validity of laboratory-based surveillance for detection of respiratory syncytial virus seasons

In this study, we validated the Centers for Disease Control and Prevention's use of a 10% threshold of median proportion of positive laboratory tests (median proportion positive (MPP)) to identify respiratory syncytial virus (RSV) seasons against a standard based on hospitalization claims. Medicaid fee-for-service recipients under 2 years of age from California, Florida, Illinois, and Texas (1999-2004), continuously eligible since birth, were categorized for each week as high-risk or low-risk with regard to RSV-related hospitalization based on medical and pharmacy claims data and birth certificates. Weeks were categorized as on-season if the RSV hospitalization incidence rate in high-risk children exceeded the seasonal peak of the incidence rate in low-risk children. Receiver operating characteristic (ROC) curves were used to measure the ability of MPP to discriminate between on-season and off-season weeks as determined from hospitalization data. Areas under the ROC curve ranged from 0.88 (95% confidence interval: 0.83, 0.92) in Illinois to 0.96 (95% confidence interval: 0.94, 0.98) in California. Requiring at least 5 positive tests in addition to the 10% MPP threshold optimized accuracy, as indicated by minimized root mean square errors. The 10% MPP with the added requirement of at least 5 positive tests is a valid method for identifying clinically significant RSV seasons across geographically diverse states.

Clinical and radiological features of respiratory syncytial virus in solid organ transplant recipients: a single-center experience

BACKGROUND

Respiratory syncytial virus (RSV) infections range from upper respiratory illness to severe lower respiratory disease. There is no universally accepted treatment for RSV in solid organ transplant (SOT) recipients.

METHODS

Retrospective review of adult SOT patients with RSV infections, between January 2007 and December 2009, in a single transplant center was performed.

RESULTS

During the 3-year period, a total of 24 adults developed RSV infection, including 12 (50%) SOT recipients (5 kidneys, 4 livers, and 3 lungs). Most cases were seen in 2009 during the influenza H1N1 pandemic, likely as a result of increased testing. In 83% of the cases, the diagnosis was based on RSV antigen detection, which was also used to follow subsequent shedding (mean duration: 20.6 days). Most of the cases presented with lower respiratory disease and required hospitalization. All the patients were on at least two classes of immunosuppressive drugs. We observed a lower lymphocyte count in patients with lower respiratory tract infection. Computed tomography was superior to chest x-ray in demonstrating pulmonary disease, with the most common findings being pulmonary nodules and ground-glass opacities. Novel radiographic findings were small cavities and pleural effusions. No co-infections were documented, and no mortality could be attributed to RSV. Inhaled or oral ribavirin was administered in 67% of the cases, with variations in the treatment regimens.

CONCLUSION

SOT recipients accounted for half of all adult cases of RSV at our institution. Type and length of treatment varied widely, and we cannot conclude that outcomes differed between treatments with oral or inhaled ribavirin. Current therapeutic management of RSV in SOT is empiric, and can be rather expensive and difficult, without clear evidence of effectiveness.

Palivizumab utilization and compliance: trends in respiratory syncytial virus prophylaxis in Florida

OBJECTIVES

To analyze adherence to guidelines to prevent respiratory syncytial virus hospitalization and to a monthly immunoprophylaxis schedule in the absence of prior authorization requirements.

STUDY DESIGN

Among Florida Medicaid fee-for-service recipients 0 to 2 years of age from the 1998/1999 season through the 2004/2005 season with available birth certificates, we identified indications for palivizumab prophylaxis based on claims data. At least 4 doses of palivizumab in the 5 core season-months were considered full season coverage.

RESULTS

Of 302 101 children-seasons, 6089 were associated with 24 469 doses of palivizumab. In the 2004/2005 season, 73.6% of children with chronic lung disease received immunoprophylaxis, 67.6% children with gestational age <32 weeks, 37% with congenital heart disease, 26.4% with cystic fibrosis, and 19.4% with severe immunodeficiency. Multiple indications increased the likelihood for prophylaxis from 34.9% to 80.4%. Full season coverage was consistent across indications at approximately 70%. From the 1998/1999 season through the 2004/2005 season, 8038 doses were administered during 2051 children-seasons without any indication; mostly (69.6%) where premature children had exceeded the recommended age range for prophylaxis.

CONCLUSIONS

High utilization rates were found in children with multiple indications, and compliance with a monthly schedule was consistently high. One third of doses were administered outside of guidelines, suggesting suboptimal utilization of resources in the absence of prior authorization.

A novel active respiratory syncytial virus surveillance system in the United States: variability in the local and regional incidence of infection

BACKGROUND

To characterize the onset, peak, and duration of the RSV season in major metropolitan areas in the United States as determined from laboratory test data collected by a novel RSV surveillance program (RSV Alert), including regional and national trends.

METHODS

We prospectively analyzed results of more than 600,000 tests collected weekly during 3 seasons (2004/2005-2006/2007) by the RSV Alert program. More than 200 institutions participated in the first 2 seasons of the program, and more than 600 sites in the third. Data were analyzed for trends in season onset, offset, and duration at the local, regional, and national levels.

RESULTS

Considerable variability in season onset and duration was noted between metropolitan areas located geographically within the same region. Seasonal outbreaks of RSV consistently peaked first, concluded earliest, and were of longest duration in the Southern region. The onset of the RSV season occurred latest and peaked last in the Midwest region each season.

CONCLUSIONS

The variable nature of outbreaks observed between metropolitan areas located geographically within the same regions of the country is highlighted through data collected for 3 consecutive seasons. The RSV Alert program is a valuable reporting system that provides real-time surveillance data at a city/local level nationwide and has potential to aid clinicians in decisions regarding RSV management.

Correlation between respiratory syncytial virus (RSV) test data and hospitalization of children for RSV lower respiratory tract illness in Florida

BACKGROUND

Florida experiences year-round outbreaks of respiratory syncytial virus (RSV), but it is unknown if there is a correlation between RSV virology data and disease-related hospitalizations. We analyzed RSV surveillance and hospitalization data for the state of Florida to determine if there is an association between seasonal virology data and the incidence of International Classification of Diseases, 9th revision, clinical modification (ICD-9-CM) coded hospitalizations for RSV lower respiratory tract illness.

METHODS

We conducted a retrospective analysis for each of 5 regions of Florida for 4 years (2001-2004) of monthly RSV surveillance data presented on the Florida Department of Health website and hospitalization data provided by the Agency for Health Care Administration. RSV was considered present when > or =10% of laboratory tests were positive in a given month and the duration of seasons was determined by the number of consecutive months threshold values were exceeded. Hospitalizations in children 24 months of age and younger were defined as RSV related if any of the following RSV-specific ICD-9-CM codes appeared on the discharge summary: 079.6 RSV; 466.11 acute bronchiolitis caused by RSV; and 480.1 pneumonia caused by RSV.

RESULTS

RSV circulated year-round statewide and seasons ranged from 7-8 months in the southwest, northwest, and north regions of Florida to 11-12 months in the central and southeast regions, respectively. More than 23,000 children younger than 24 months of age were hospitalized throughout the state for an RSV-related illness during the 4-year period, with almost 20,000 (86%) of the admissions in infants less than 12 months of age. There were 23 hospitalizations yearly per 1000 births and more than 90% of discharges occurred during the defined RSV seasons.

CONCLUSIONS

To our knowledge, this is the first study to demonstrate a positive correlation between RSV test data and hospitalizations both statewide and for individual regions within Florida. It would be prudent for clinicians to obtain results of local RSV virology data to guide decisions on timing of prophylaxis to prevent RSV hospitalizations.

Respiratory syncytial virus seasonality in southeast Florida: results from three area hospitals caring for children

Southeast Florida generally experiences longer seasonal epidemics of respiratory syncytial virus (RSV) than other parts of the country. In this report, the primary objective was to more accurately define the onset, peak, and duration of the RSV season in Southeast Florida. The results obtained for this region were also compared with those reported for the state and for the nation. Seasonal patterns for RSV in Southeast Florida were analyzed based on the total number of RSV tests performed, number of positive tests, and percent of positive tests in children presenting with bronchiolitis to 3 emergency departments from January 2003 through December 2006. RSV was detected by rapid diagnostic testing and considered to be present at epidemic levels when at least 10% of performed tests were positive during a given month. During the entire 12 months of 2003 and 2006, RSV was detected above epidemic levels. The RSV-detection test positivity rate was less than 10% in only 6 months of 48 total months of observation, but during the months that were below epidemic threshold, RSV was still frequently identified. RSV activity increased during July, peaked during October, and waned during the spring months. These findings were nearly identical to those recently reported in other studies, confirming that RSV circulated at epidemic levels in Southeast Florida during most of the 4-year observation period and remained a significant cause of respiratory disease and hospitalization throughout the year. Strategies for RSV prophylaxis in at-risk children in South Florida should consider results of local RSV test detection.