Progress continued on a vaccine against respiratory syncytial virus (RSV) for older adults, while the country experienced a resurgence in infections among young children this year that caused the CDC to issue a Health Advisory on the illness.
Vaccine Development in Older Adults Continues to Accelerate
Janssen's adenoviral vector vaccine against RSV in older adults was safe and effective, particularly against severe disease. Data from the phase IIb CYPRESS trial presented at this year's IDWeek conference showed that the Ad.26 RSV preF-based vaccine had 80% vaccine efficacy (94.2% CI 52.2%-92.9%) against RSV with at least three lower respiratory tract infection (LRTI) symptoms and 69.8% efficacy (94.2% CI 43.7%-84.7%) against RSV with at least two LRTI symptoms or one LRTI symptom and one systemic symptom.
"One could say the vaccine was 69.8% effective to prevent any symptomatic, acute [RSV] illness," said Ann Falsey, MD, of the University of Rochester in New York.
The vaccine was also well-tolerated, with no safety signals, and elicited robust and durable humoral and cellular immune responses.
Overall, 5,782 adults 65 and older, including those with "stable" chronic diseases, were enrolled in the study and randomized to receive either vaccine or placebo. The trial began in August 2019 and is slated to last over the course of three RSV seasons, for a total of 2.6 years during which participants will be surveilled for acute respiratory infections.
Given these results, the phase III EVERGREEN study of the vaccine is currently enrolling.
Elsewhere in vaccine development, Pfizer announced the start of its phase III RENOIR trial (RSV vaccine efficacy in Older adults Immunized Against RSV disease) in September, with its bivalent prefusion F subunit investigational vaccine candidate (RSVpreF) in adults ages 60 and up.
Moderna also jumped into the fray, announcing positive pre-clinical data from a single shot COVID/RSV/flu vaccine in September, while its phase II/III study, ConquerRSV, on its vaccine candidate, mRNA-1345, launched in November.
RSV Takes 2020 Off But Roars Back in 2021
Some respiratory viruses, such as RSV and flu, took a break during 2020-2021, as incidence in kids dipped in the first year of the pandemic. Data presented at IDWeek found that while kids were still being hospitalized for rhinovirus and enterovirus, the combined positivity rate of influenza, respiratory syncytial virus (RSV), and other respiratory viruses (39.5%) was significantly lower in 2020-2021 compared to each of the prior three seasons (P<0.001):
- 2019-2020: 75.4%
- 2018-2019: 71.3%
- 2017-2018: 69.4%
Researchers analyzed data on 37,676 children (of 69,403 eligible) who presented to emergency departments or were hospitalized for acute respiratory illness and tested positive for a respiratory virus from December 2016 to January 2021 at seven pediatric hospitals participating in the CDC's New Vaccine Surveillance Network.
This trend was coupled with the lowest rate of influenza since 1997. CDC researchers found that less than 0.4% of respiratory samples tested positive for influenza per week of flu season, with similar patterns in parainfluenza viruses, RSV, and common human coronaviruses.
Sonja Olsen, PhD, of the CDC, said that they expect RSV activity to peak sometime between October and December each year instead of increased circulation in early spring.
"As pandemic mitigation measures continue to be adjusted, we might expect to see more changes in the circulation of these viruses, including a return to pre-pandemic circulation as seen for rhinoviruses and enteroviruses," Olsen added.
Sure enough, CDC issued a Health Advisory in June 2021 about increased incidence of RSV in parts of the southern U.S.
In October, FDA granted emergency use authorization (EUA) for PerkinElmer's PKamp Respiratory SARS-CoV-2 RT-PCR Panel 1 assay, an RT-PCR test that can differentiate between COVID, flu, and RSV.
Rising Hospitalization Costs for RSV-Related Illness in Kids
A study in JAMA Network Open suggested that rising costs of hospitalization for bronchiolitis in infants in the past decade, which is primarily caused by RSV infection, may reflect both changing coding practices and a growing tendency to send young kids to the ICU.
From 2010 to 2019, the median standardized cost per bronchiolitis hospitalization among kids 2 years or younger rose from $5,636 to $6,973. At the same time, the proportion treated in the ICU more than doubled, growing from 12.4% to 25.9%, according to data from Pediatric Health Information Systems (PHIS) database.
Other notable stories this year included:
The Technological Marvel of Combination Vaccines
The COVID Crisis Has Trickled Down to Our Kids
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