Respiratory syncytial virus-associated deaths in the United States according to death certificate data, 2005 to 2016

Severe respiratory syncytial virus disease

The burden of respiratory syncytial virus (RSV) disease is widely recognized. Main risk factors for severe disease, such as extreme ages, chronic cardiopulmonary conditions, and immunosuppression, typically coincide with poorer outcomes. While the majority of RSV hospitalizations involve healthy children, a higher proportion of hospitalized adults with underlying conditions need intensive care. Presently, treatment primarily consists of supportive measures. RSV-induced wheezing should be distinguished from respiratory tract thickening, without response to bronchodilators. Obstructive RSV disease frequently overlaps with viral pneumonia. Non-invasive mechanical ventilation and high-flow oxygen therapy represented significant advancements in the management of severe RSV disease in children and may also hold considerable importance in specific phenotypes of RSV disease in adults. Most severe infections manifest with refractory hypoxemia necessitating more advanced ventilatory support and/or extracorporeal membrane oxygenation therapy. Although bacterial co-infection rates are low, they have been associated with worse outcomes. Antibiotic prescription rates are high. Accurately diagnosing bacterial co-infections remains a challenge. Current evidence and antibiotic stewardship policies advise against indiscriminate antibiotic usage, even in severe cases. The role of currently developing antiviral therapies in severe RSV disease will be elucidated in the coming years, contingent upon the success of new vaccines and immune passive strategies involving nirsevimab.

Next Generation Mucosal Vaccine Strategy for Respiratory Pathogens

Inducing humoral and cytotoxic mucosal immunity at the sites of pathogen entry has the potential to prevent the infection from getting established. This is different from systemic vaccination, which protects against the development of systemic symptoms. The field of mucosal vaccination has seen fewer technological advances compared to nucleic acid and subunit vaccine advances for injectable vaccine platforms. The advent of the next-generation adenoviral vectors has given a boost to mucosal vaccine research. Basic research into the mechanisms regulating innate and adaptive mucosal immunity and the discovery of effective and safe mucosal vaccine adjuvants will continue to improve mucosal vaccine design. The results from clinical trials of inhaled COVID-19 vaccines demonstrate their ability to induce the proliferation of cytotoxic T cells and the production of secreted IgA and IgG antibodies locally, unlike intramuscular vaccinations. However, these mucosal vaccines induce systemic immune responses at par with systemic vaccinations. This review summarizes the function of the respiratory mucosa-associated lymphoid tissue and the advantages that the adenoviral vectors provide as inhaled vaccine platforms.

Efficacy and Safety of a Bivalent RSV Prefusion F Vaccine in Older Adults

BACKGROUND

Respiratory syncytial virus (RSV) infection causes considerable illness in older adults. The efficacy and safety of an investigational bivalent RSV prefusion F protein-based (RSVpreF) vaccine in this population are unknown.

METHODS

In this ongoing, phase 3 trial, we randomly assigned, in a 1:1 ratio, adults (≥60 years of age) to receive a single intramuscular injection of RSVpreF vaccine at a dose of 120 μg (RSV subgroups A and B, 60 μg each) or placebo. The two primary end points were vaccine efficacy against seasonal RSV-associated lower respiratory tract illness with at least two or at least three signs or symptoms. The secondary end point was vaccine efficacy against RSV-associated acute respiratory illness.

RESULTS

At the interim analysis (data-cutoff date, July 14, 2022), 34,284 participants had received RSVpreF vaccine (17,215 participants) or placebo (17,069 participants). RSV-associated lower respiratory tract illness with at least two signs or symptoms occurred in 11 participants in the vaccine group (1.19 cases per 1000 person-years of observation) and 33 participants in the placebo group (3.58 cases per 1000 person-years of observation) (vaccine efficacy, 66.7%; 96.66% confidence interval [CI], 28.8 to 85.8); 2 cases (0.22 cases per 1000 person-years of observation) and 14 cases (1.52 cases per 1000 person-years of observation), respectively, occurred with at least three signs or symptoms (vaccine efficacy, 85.7%; 96.66% CI, 32.0 to 98.7). RSV-associated acute respiratory illness occurred in 22 participants in the vaccine group (2.38 cases per 1000 person-years of observation) and 58 participants in the placebo group (6.30 cases per 1000 person-years of observation) (vaccine efficacy, 62.1%; 95% CI, 37.1 to 77.9). The incidence of local reactions was higher with vaccine (12%) than with placebo (7%); the incidences of systemic events were similar (27% and 26%, respectively). Similar rates of adverse events through 1 month after injection were reported (vaccine, 9.0%; placebo, 8.5%), with 1.4% and 1.0%, respectively, considered by the investigators to be injection-related. Severe or life-threatening adverse events were reported in 0.5% of vaccine recipients and 0.4% of placebo recipients. Serious adverse events were reported in 2.3% of participants in each group through the data-cutoff date.

CONCLUSIONS

RSVpreF vaccine prevented RSV-associated lower respiratory tract illness and RSV-associated acute respiratory illness in adults (≥60 years of age), without evident safety concerns. (Funded by Pfizer; RENOIR ClinicalTrials.gov number, NCT05035212; EudraCT number, 2021-003693-31.).

Clinical impact of healthcare-associated respiratory syncytial virus in hospitalized adults

OBJECTIVE

To describe the clinical impact of healthcare-associated (HA) respiratory syncytial virus (RSV) in hospitalized adults.

DESIGN

Retrospective cohort study within a prospective, population-based, surveillance study of RSV-infected hospitalized adults during 3 respiratory seasons: October 2017-April 2018, October 2018-April 2019, and October 2019-March 2020.

SETTING

The study was conducted in 2 academically affiliated medical centers.

PATIENTS

Each HA-RSV patient (in whom RSV was detected by PCR test ≥4 days after hospital admission) was matched (age, sex, season) with 2 community-onset (CO) RSV patients (in whom RSV was detected ≤3 days of admission).

METHODS

Risk factors and outcomes were compared among HA-RSV versus CO-RSV patients using conditional logistic regression. Escalation of respiratory support associated with RSV detection (day 0) from day -2 to day +4 was explored among HA-RSV patients.

RESULTS

In total, 84 HA-RSV patients were matched to 160 CO-RSV patients. In HA-RSV patients, chronic kidney disease was more common, while chronic respiratory conditions and obesity were less common. HA-RSV patients were not more likely to be admitted to an ICU or require mechanical ventilation, but they more often required a higher level of care at discharge compared with CO-RSV patients (44% vs 14%, respectively). Also, 29% of evaluable HA-RSV patients required respiratory support escalation; these patients were older and more likely to have respiratory comorbidities, to have been admitted to intensive care, and to die during hospitalization.

CONCLUSIONS

HA-RSV in adults may be associated with escalation in respiratory support and an increased level of support in living situation at discharge. Infection prevention and control strategies and RSV vaccination of high-risk adults could mitigate the risk of HA-RSV.

Respiratory syncytial virus disease burden in adults aged 60 years and older in high-income countries: A systematic literature review and meta-analysis

BACKGROUND

Respiratory syncytial virus (RSV)-associated acute respiratory infection (ARI) is an underrecognized cause of illness in older adults. We conducted a systematic literature review and meta-analysis to estimate the RSV disease burden in adults ≥60 years in high-income countries.

METHODS

Data on RSV-ARI and hospitalization attack rates and in-hospital case fatality rates (hCFR) in adults ≥60 years from the United States, Canada, European countries, Japan, and South Korea were collected based on a systematic literature search (January 1, 2000-November 3, 2021) or via other methods (citation search, unpublished studies cited by a previous meta-analysis, gray literature, and an RSV-specific abstract booklet). A random effects meta-analysis was performed on estimates from the included studies.

RESULTS

Twenty-one studies were included in the meta-analysis. The pooled estimates were 1.62% (95% confidence interval [CI]: 0.84-3.08) for RSV-ARI attack rate, 0.15% (95% CI: 0.09-0.22) for hospitalization attack rate, and 7.13% (95% CI: 5.40-9.36) for hCFR. In 2019, this would translate into approximately 5.2 million cases, 470,000 hospitalizations, and 33,000 in-hospital deaths in ≥60-year-old adults in high-income countries.

CONCLUSIONS

RSV disease burden in adults aged ≥60 years in high-income countries is higher than previously estimated, highlighting the need for RSV prophylaxis in this age group.

Adult Respiratory Syncytial Virus Infection and Hypoxic Cardiac Arrest—Coexistent or Causal? A Hypothesis-Generating Case Report

Respiratory syncytial virus (RSV) is a well-known pathogen in paediatric patients. However, it also causes substantial morbidity and mortality in adults, posing a major healthcare problem. We present a patient with chronic pulmonary conditions and an acute RSV infection, thus leading to cardiac arrest (CA). We speculate that RSV as the causative agent for CA should be considered in post-resuscitation care. From a wider public health perspective, immuno-naivety for RSV caused by the coronavirus disease 2019 pandemic may induce a severe rise in cases, morbidity, and mortality in the future.

Mortality Associated With Respiratory Syncytial Virus, Bronchiolitis, and Influenza Among Infants in the United States: A Birth Cohort Study From 1999 to 2018

BACKGROUND

Infant mortality due to respiratory syncytial virus (RSV) in the United States is not well understood.

METHODS

From 1999 to 2018, RSV, bronchiolitis, and influenza deaths were described for infants <1 year using linked birth/death datasets from the National Vital Statistics System. Mortality was described overall and by infant birth and death characteristics. Bronchiolitis was included as the plausible upper limit of RSV, while influenza served as a comparator.

RESULTS

Total infant deaths were 561 RSV, 1603 bronchiolitis, and 504 influenza, and rates were 6.9 (95% confidence interval [CI], 6.4-7.5), 19.8 (95% CI, 18.9-20.8), and 6.2 (95% CI, 5.7-6.8) per 1 000 000 live births, respectively. The highest RSV rates were observed among <29 weeks' gestational age infants (103.5; 95% CI, 81.8-129.1), American Indian/Alaskan Native (20.3; 95% CI, 11.6-33.0), and Medicaid-insured (7.3; 95% CI, 5.9-8.9). However, RSV mortality burden was greatest in full-term (53.7%), white (44.9%), and Medicaid-insured (61.7%) infants. Deaths outside the inpatient setting were 21% and 54% for RSV and bronchiolitis; more Medicaid- (58%) and other/unknown-insured (69%) infants with bronchiolitis died outside of the inpatient setting, compared to privately insured infants (48%) (P = .0327).

CONCLUSIONS

These national estimates emphasize the importance of considering all infants across all healthcare settings when describing RSV mortality.

Mortality Among US Infants and Children Under 5 Years of Age with Respiratory Syncytial Virus and Bronchiolitis: A Systematic Literature Review

Background

A systematic literature review was conducted to summarize the mortality (overall and by disease severity factors) of US infants and children aged <5 years with respiratory syncytial virus (RSV) or all-cause bronchiolitis (ACB).

Methods

Comprehensive, systematic literature searches were conducted; articles were screened using prespecified eligibility criteria. A standard risk of bias tool was used to evaluate studies. Mortality was extracted as the rate per 100 000 or the case fatality ratio (CFR; proportion of deaths among RSV/ACB cases).

Results

Among 42 included studies, 36 evaluated inpatient deaths; 10 used nationally representative populations updated through 2013, and only 2 included late-preterm/full-term otherwise healthy infants and children. The RSV/ACB definition varied across studies (multiple International Classification of Diseases [ICD] codes; laboratory confirmation); no study reported systematic testing for RSV. No studies reported RSV mortality rates, while 3 studies provided ACB mortality rates (0.57–9.4 per 100 000). CFRs ranged from 0% to 1.7% for RSV (n = 15) and from 0% to 0.17% for ACB (n = 6); higher CFRs were reported among premature, intensive care unit-admitted, and publicly insured infants and children.

Conclusions

RSV mortality reported among US infants and children is variable. Current, nationally representative estimates are needed for otherwise healthy, late-preterm to full-term infants and children.

The Use of Death Certificate Data to Characterize Mortality Associated With Respiratory Syncytial Virus, Unspecified Bronchiolitis, and Influenza in the United States, 1999-2018

BACKGROUND

Death certificate data can improve our understanding of the mortality burden associated with respiratory syncytial virus (RSV) and influenza.

METHODS

We used International Classification of Diseases, Tenth Revision codes listed on death certificates to characterize deaths from 1999 to 2018 as RSV, influenza, and unspecified bronchiolitis. We described the distribution of each cause of death by age, sex, race/ethnicity, place of death, and contributing causes of death.

RESULTS

Over the 20-year study period, RSV, bronchiolitis, and influenza were listed as the underlying causes of death on 932, 1046, and 52 293 death certificates, respectively. Children <1 year of age accounted for 39% of RSV and bronchiolitis deaths, while 72% of influenza deaths were in adults ≥65 years. Children <1 year were more likely to die outside of the hospital from RSV, bronchiolitis, or influenza compared to all causes (P < .01), and black infants had the highest mortality rate for all 3 causes. Most infants dying from RSV did not have a high-risk condition listed on the death certificate. Death certificates captured 20%-60% of estimated excess RSV-attributable mortality in infants and <1% in seniors.

CONCLUSIONS

Thorough reporting on death certificates is an important public health goal, especially as new therapeutics become available. Infants had higher odds of dying out of hospital from respiratory pathogens compared to other causes, and race/ethnicity alone did not explain this disparity.