1. SEASONAL RESPIRATORY INFECTION AND EXACERBATION OF CHRONIC CARDIOPULMONARY DISEASE

SEASONAL RESPIRATORY INFECTION AND EXACERBATION OF CHRONIC
CARDIOPULMONARY DISEASE (A Narrative Review)

Shaikh Mohammed Kamil, Abu Fazal Shaikh
International Higher School of Medicine (IHSM)
Bishkek, Kyrgyzstan

Abstract
Relevance: Respiratory viral infection peaks seasonally and is linked to exacerbation of
chronic cardiopulmonary disease, but whether this link is uniform across conditions, and whether
circadian- and vitamin D-related immunity contributes independently, remains unclear.
Goals and Objectives: To synthesize evidence on the seasonal association between
respiratory infection and exacerbation of chronic obstructive pulmonary disease (COPD), asthma,
congestive heart failure (CHF), and idiopathic pulmonary fibrosis (IPF), and to evaluate
circadian/vitamin D immune variation as a candidate mechanism.
Materials and Methods: A narrative synthesis of PubMed and Scite literature (2021-2026,
one earlier source retained) used Boolean searches for seasonality, respiratory infection, and
exacerbation; seventeen sources were retained.
Results: Respiratory infection showed a consistent winter peak coinciding with COPD,
asthma, and CHF exacerbation. This association was disease-specific: COPD/asthma seasonality
weakened sharply during pandemic-era infection suppression and rebounded, while IPF
exacerbations retained winter seasonality independent of infection. A UK Biobank cohort
(n=329,261) showed confounder-independent seasonal immune variation, supporting a
complementary circadian pathway; vitamin D’s protective role was inconsistent.
Conclusions: The infection-exacerbation link is disease-specific: strongest for
COPD/asthma, less definitive for CHF, insufficient for IPF. Circadian/vitamin D immune variation
remains a plausible, unproven complementary factor, supporting existing seasonal prevention over
new protocols.
Keywords: seasonality, respiratory infection, COPD exacerbation, idiopathic pulmonary
fibrosis, circadian immunity, vitamin D