4 Discussion
During the lockdown period, a consistent improvement in asthma morbidity has been observed across several studies, attributed to behavioural changes that led to decreased exposure to environmental and infectious triggers and improved treatment compliance. It is difficult to quantify the contribution of each specific behavioural change towards the reduction of asthma morbidity, although respiratory viral infections have been proposed as one of the most important and well-established causes of asthma exacerbations and hospitalisations.21,22 Lockdowns were directly aiming to decrease the spread of COVID-19 through social distancing, leading to an inevitable decrease in other infections from common respiratory viruses. Indeed, many studies showed a reduction in the spread of common respiratory viruses, which partly explain the reduction in asthma-related ED visits and hospitalisations across the globe.
However, as Dondi A, et al have pointed out, the improvement in clinical picture was most probably due to synergistic effects of many behavioural changes brought by lockdowns, with the most important being the reductions in pollution exposure and respiratory infections.15 Other contributing factors may well be the reduction in allergen exposure due to less time spent outdoors and the increased treatment compliance. The relationship between environmental triggers and asthma exacerbations is well-established and there are ongoing studies on mitigation strategies focusing on reduction of exposures to environmental hazards, aiming to reduce morbidity of vulnerable groups such as children with asthma.41Furthermore, poor compliance and poor inhaler technique are known major preventable causes of poor asthma control.42 The pandemic fear and the concerns for association of asthma with worse COVID-19 outcomes have improved compliance,36 possibly the treatment technique and the vigilance for recognition of signs of poorly controlled asthma.
The findings of this review raise questions on how public health measures may improve asthma control after the pandemic has ended. School-based interventions are a good example of a strategy that can reduce the exposure of children with asthma to respiratory viruses. A national-level study in Italy aiming to improve health behaviours in schools examined raising awareness on disease spreading, teaching promotion of hygienic behaviours and access to antiseptics. During the pandemic, infection incidence of SARS-CoV-2 was 14% lower in schools participating in the intervention compared to regional incidence.43 Mask wearing and social distancing were also shown to reduce SARS-CoV-2 spread,44 and may benefit asthmatic children after the pandemic in a similar manner. However, public acceptability and attitudes towards each intervention should be considered, especially in the case of mask wearing and social distancing, as these involve trade-offs between preserving children’s physical health versus mental health and social development.45,46 Other strategies could focus on air quality by improving school infrastructures aiming to maintain a better indoor air-quality in areas affected by anthropogenic or non-anthropogenic emissions, or during high pollen seasons, and encourage indoor activities for vulnerable children. Design of more efficient buildings with better window and door sealing, or installation of air purifiers in classrooms and houses are such potential measures. Furthermore, timely population alerts on days with high environmental pollution along with dissemination of recommendations on minimising transport, time spent outdoors and instructions on how to maintain a better indoor air quality are also relevant.41Finally, better compliance and patient teaching on asthma treatment should continue to be important aspects of primary care.
Some of the presented studies were limited by the small size and isolated sources of their data, such as data from ED visits reported from single hospitals. However, the consistency and robustness of the findings across these studies suggest a real effect of lockdowns on asthma morbidity. Another limitation is the administrative nature of the data in several studies, as they emerged from hospital encounters which may have been affected by pandemic-related hospital avoidance. However, a similar strong trend of improved asthma control was also reported by the few prospective and community-based studies.11,38,40