TABLE 1

Viral causes of common respiratory syndromes

Virus	Strength of association with clinical syndrome
Virus	Common cold	Croup	Bronchiolitis	Influenza-like illness	Pneumonia
Influenza A or B	Moderate	Weak	Weak	Strong	Strong
Respiratory syncytial virus	Moderate	Moderate	Strong	Moderate	Strong
SARS-CoV-2	Moderate	Weak	Negligible	Strong	Strong
Seasonal coronaviruses^a	Moderate	Weak	Weak	Weak	Weak
Rhinovirus	Strong	Weak	Negligible	Weak	Moderate
Human metapneumovirus	Moderate	Weak	Strong	Weak	Moderate
Parainfluenza viruses 1–4	Moderate	Strong	Moderate	Weak	Moderate
Adenoviruses	Moderate	Weak	Negligible	Moderate	Strong