Assessing the Impact of Acute Respiratory Illnesses on the Risk of Subsequent Respiratory Illness

Abstract

Background: Whether acute respiratory illnesses (ARIs), often associated with virus detection, are associated with lower risk for subsequent ARI remains unclear. We assessed the association between symptomatic ARI and subsequent ARI in young children.

Methods: In a prospective cohort of Peruvian children <3 years, we examined the impact of index ARI on subsequent ARI risk. Index ARI were matched with ≤3 asymptomatic observations and followed over 28 days. We compared risk of subsequent ARI between groups using conditional logistic regression adjusting for several covariates, accounting for repeat observations from individual children.

Results: Among 983 index ARI, 339 (34%) had an ARI event during follow-up, compared with 876/2826 (31%) matched asymptomatic observations. We found no significant association of index ARI and subsequent ARI risk during follow-up overall (adjusted odds ratio [aOR], 1.10; 95% confidence interval [CI], .98-1.23) or when limited to index ARI with respiratory viruses detected (aOR, 1.03; 95% CI, .86-1.24). Similarly, when the outcome was limited to ARI in which viruses were detected, no significant association was seen (aOR, 1.05; 95% CI, .87-1.27).

Conclusions: ARIs were not associated with short-term protection against subsequent ARI in these children. Additional longitudinal studies are needed to understand drivers of recurrent ARI in young children.

Keywords: acute respiratory illness; children; respiratory viruses; viral interference.

Figure 1.

Illustration of index acute respiratory illness (ARI) observation and age-matched (± 1 month) asymptomatic observation. To be eligible to contribute an asymptomatic observation, children must have been asymptomatic for 28 days prior to the ARI onset and throughout the ARI and 7-day post-ARI period.

Figure 2.

Association between index ARI compared to matched asymptomatic observations and occurrence of subsequent ARI during 28-day follow-up period. Circles indicate point estimate for adjusted odds ratio; bars indicate 95% confidence intervals. Abbreviations: ARI, acute respiratory illness; PCV7, 7-valent pneumococcal conjugate vaccine.