Age-dependent rebound in asthma exacerbations after COVID-19 lockdown

Abstract

Background: Virus mitigation measures enacted early in the coronavirus infectious disease 2019 (COVID-19) pandemic suppressed common respiratory viruses and reduced the number of obstructive lung disease exacerbations. However, many localities began to ease these precautions in the year 2021, leading to a resurgence of non-COVID viruses. How asthma and chronic obstructive pulmonary disease (COPD) activity responded to this upswing in viral abundance is unclear.

Objective: Our aim was to examine how viral resurgence during the relaxation of COVID-19 restrictions affected asthma and COPD exacerbations.

Methods: We analyzed electronic medical records for emergency department (ED) respiratory virus positivity, asthma visits, and COPD visits. We compared the 52-week interval before the COVID-19 restrictions (the pre-lockdown period [March 22, 2019-March 19, 2020]), the 52-week period immediately following enactment of the restrictions (the lockdown period [March 20, 2020-March 18, 2021]), and the 52-week period thereafter (the post-lockdown period [March 19, 2021-March 18, 2022]). We used MetaCYCLE to analyze seasonal trends in our data.

Results: The post-lockdown period was marked by a 400% increase in viral positivity compared with during the lockdown period. Asthma- and COPD-related ED visits each rose 37% compared with during the lockdown, with the rebound in asthma ED visits concentrated in individuals younger than 20 years. Interestingly, after the lockdown period, asthma ED visits overcorrected in children younger than 5 years, rising 81% compared with before the lockdown. Seasonal rhythms in asthma and COPD exacerbations were suppressed during the lockdown and recovered after the lockdown.

Conclusions: COVID-19 precautions had the unexpected effect of magnifying early-childhood asthma activity once common respiratory viruses recurred. These results may have implications for the future use of virus mitigation strategies in young children.

Keywords: Asthma; COPD; COPD, Chronic obstructive pulmonary disease; COVID-19; COVID-19, Coronavirus disease 2019; ED, Emergency department; RV, Rhinovirus; lockdown; respiratory viruses.

Fig 1

Rebound in respiratory viruses and obstructive airway disease exacerbations in the year following the COVID-19 lockdown. A, ED viral detection (upper panel) and total tests performed (lower panel) for 6 common respiratory viruses associated with asthma exacerbations (events per week). Time frames denoted as occurring before the lockdown (control), during the lockdown (viral suppression), and after the lockdown (viral rebound) are separated by dashed lines (see the Supplementary Methods). The total number of events per time frame are depicted within each panel. B, Viral positivity rate (positive tests/total) for respiratory viruses shown in (A). Pre-lockdown, lockdown, and post-lockdown intervals are separated by thin vertical lines. Season boundaries are provided on the x-axis as a visual aid. AV, Adenovirus; F, fall; FLU, influenza; ParaFlu, parainfluenza: RSV, respiratory syncytial virus; RV, rhinovirus; S, summer; Sp, spring; W, winter.

Fig 2

Supranormal levels of ED visits for asthma in young children after the lockdown. Histograms depicting cumulative clinical events during the pre-lockdown (solid line), lockdown (dashed line), and post-lockdown (dotted line) periods. Data are binned in 5-year intervals (eg, 0 represents patients aged 0-5 years). Upper panel, ED visits for asthma (blue lines) and COPD (red lines). Middle panel, positive tests for common respiratory viruses (see Fig 1). Lower panel, Spearman rank correlation coefficient between viral detection and asthma- (red circles) or COPD-related ED visits (red squares) across the entire study period as a function of age. Best-fit trend lines and goodness of fit (r²) are depicted.

Fig 3

Return of asthma and COPD seasonality with viral resurgence after the lockdown. Data represent weekly ED visits for asthma (blue symbols) and COPD (red symbols). Best-fit lines, statistical significance, and rhythm parameters (exposed in units of weeks) were generated by using MetaCYCLE analysis and are depicted within each graph (see the Supplementary Methods). A, Amplitude; φ, acrophase (time of maximum excursion from baseline); F, fall; S, summer; Sp, spring; τ, period duration; W, winter.