Daijiworld Media Network - New Delhi
New Delhi, Oct 9: The combined circulation of common respiratory viruses is a stronger indicator of seasonal hospital admissions than the activity of individual pathogens, according to a study published in the Journal of Medical Microbiology.
Researchers analysed 1,801 hospital admissions for acute respiratory infections between November 2019 and March 2020, before the widespread emergence of SARS-CoV-2. The study examined links between specific viruses, patients’ ages, environmental factors and clinical conditions.
The findings showed that different respiratory viruses were associated with distinct clinical presentations, including pneumonia, bronchiolitis and exacerbations of asthma and chronic obstructive pulmonary disease (COPD).
Influenza A was frequently associated with pneumonia, with 76.5% of patients infected with influenza A alone admitted with the condition. The influenza A wave peaked during epidemiological week 5 of 2020, when the virus accounted for 33% of all infections tested.
Respiratory syncytial virus (RSV) was primarily associated with bronchiolitis, particularly among infants, while human rhinovirus (HRV) was the most frequently identified viral trigger of acute asthma and COPD exacerbations.
Age was also a major factor influencing the clinical presentation. Infants below one year accounted for more than 90% of bronchiolitis admissions in the group examined in relation to influenza A testing, the study reported.
Although the viruses showed preferences for particular conditions, no single pathogen was exclusively associated with one diagnosis. Viral co-infections were also uncommon.
When the researchers assessed the circulation of all respiratory viruses together, they found a strong correlation with overall hospital admissions, with a correlation coefficient of 0.88. This association was stronger than those observed for individual pathogens, suggesting that monitoring overall viral activity could help healthcare systems anticipate seasonal demand for hospital services.
The study also examined environmental factors, including ozone, sulphur dioxide, nitrogen dioxide, carbon monoxide, nitrogen oxide and fine particulate matter. After adjustments, none of the air quality variables showed a consistent independent association with admissions for acute respiratory infections.
The researchers acknowledged limitations, including the five-month observation period, the use of weekly averages for air pollution data and possible diagnostic overlap between bronchiolitis and viral pneumonia in young children.
The authors concluded that while the type of virus and the patient's age help explain specific clinical presentations, monitoring the combined circulation of respiratory viruses may provide a more reliable indication of seasonal hospital demand.