The seasonal patterns and epidemiology of viral acute respiratory infections (ARIs) have experienced notable shifts since the onset of the COVID-19 pandemic. This evolution has necessitated enhanced surveillance efforts to monitor respiratory viruses across various age groups. A recent study conducted during the 2023-24 winter season provides significant insights from Kyoto, Japan, addressing this very need.
This innovative study, spearheaded by researchers from Kyoto University alongside several medical institutions, focused on establishing age-stratified molecular surveillance to define local epidemiology of ARIs. With respiratory viruses continuing to pose risks, especially post-pandemic, the study collected samples from 2,992 patients suspected of having ARIs at five facilities over the period from December 2023 to March 2024.
Utilizing advanced testing methods including RT-PCR to detect SARS-CoV-2, influenza virus, and respiratory syncytial virus (RSV), the authors found positive cases of these three prominent viruses within 598 (20.3%), 165 (5.6%), and 40 (1.4%) of 2,949 valid samples, respectively. For samples negative for these viruses, the FilmArray Respiratory Panel was employed to explore the presence of other pathogens.
The results revealed different prevalent pathogens categorized by age groups. For children under six, rhinovirus/enterovirus was predominant, followed by RSV. School-aged children (6-17 years) exhibited higher detection rates for influenza virus and seasonal coronaviruses, whereas adults (18-64 years) showed significant SARS-CoV-2 and seasonal coronavirus cases. Elderly individuals, aged 65 and over, exhibited similar trends with SARS-CoV-2 leading.
This stratification demonstrates the significant differences found across age groups, emphasizing the need for targeted surveillance. Researchers pointed out, "This study highlights the importance of age-stratified molecular-based surveillance for comprehensive observations of the epidemiology of ARIs." The multiple viruses detected indicate how ARIs impact different demographics and underline pressing public health needs, especially for developing prevention strategies.
While traditional surveillance focused primarily on pediatric cases, this regional surveillance sheds light on infections across all ages, particularly adults who often remain undetected. For example, RSV—which typically causes mild infections—is now recognized for its potential severity among the elderly and those with pre-existing conditions.
The approach employed by the study seeks to overcome limitations from the National Epidemiological Surveillance of Infectious Diseases (NESID) systems, which are often biased and focus heavily on children. This newly developed surveillance framework not only enhances the spectrum of pathogens monitored but also collects valuable data for public health response to ARIs by age stratification.
The seasonal data reflects trends where the peak months for detection corresponded with colder temperatures, constituting typical viral behavior. Notably, the monthly data indicated SARS-CoV-2 peaked during similar high-demand winter periods, aligning with observations from past years.
The researchers concluded, "Our data will help accurately elucidate the epidemiology of viral ARIs at different ages and may help clinicians and public health professionals plan infection control and prevention strategies." This comprehensive study calls for greater emphasis on molecular diagnostics for all age groups moving forward, focusing on the importance of maintaining proactive healthcare strategies.
With additional research anticipated to explore genomic variances of detected pathogens, the findings reiterate the persistence of respiratory infections. They provide invaluable perspectives on future planning and direction for healthcare systems to address the broad spectrum of respiratory viral infections across varying age demographics.