Post COVID-19 bronchiectasis: a potential epidemic within a pandemic

KEYWORDS:

• SARS-CoV-1
• SARS-CoV-2
• COVID-19
• bronchiectasis
• complications
• follow up

Novel coronavirus disease (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and as of 29 May 2020 it has affected approximately 6 million people and caused 362 000 deaths worldwide [1]. The COVID-19 pandemic has quickly prompted research, and with information swiftly accumulating, it has been shown that SARS-CoV-2 is notably genetically similar to SARS-CoV-1, with an 86% similarity in their respective genomes [2]. SARS-CoV-1 was responsible for the SARS epidemic that ended in 2003. Little is currently known of the long-term effects in COVID-19 survivors; however, these are likely to be proportional to the severity of the infection. We can get some insight into the potential effects of COVID-19 from past experience of SARS-CoV-1 and a recent study of the long-term consequences of SARS infection in medical staff noted chronic lung injury as a sequala of the infection; pulmonary diseases were not listed as comorbidities in individuals prior to infection, but following SARS infection 38% had ‘lung injury’ at follow-up, supporting that long-lasting lung damage is a post-infectious sequela of SARS infection [3]. In addition to the interstitial changes seen in the immediate recovery phase of severe acute respiratory distress syndrome, it is likely that long-term post-infective bronchiectasis may be a more perceptible complication of this pandemic.

Bronchiectasis is permanent abnormal dilatation of one or more bronchi visualized on radiological imaging and is clinically characterized by chronic cough and recurrent respiratory infections, that significantly impact on quality of life. Bronchiectasis has several etiologies, the most common being post-infective and accounts for almost one-third of cases [4,5]. These infections are often severe respiratory infections in childhood and although multiple studies mention viral causes of post-infective bronchiectasis it is unknown what impact novel viral infections such as COVID-19 will have on the prevalence of bronchiectasis.

Age (70 years and over), cigarette smoking and underlying medical conditions, are thought to increase the severity of COVID-19 infection [6]. A recent meta-analysis describes more than a five-fold increased risk of severe COVID-19 infection in those with chronic obstructive pulmonary disease (COPD) [7]. Immunodeficiency has also been noted to be one of the strongest risk factors for severe COVID-19 infection, in which immunocompromised patients appear to be associated with faster progression and an increased requirement for admission to the Intensive Care Unit [8]. These risk factors for COVID-19 severity are also known to increase the risk of developing bronchiectasis.

A small number of studies have been published relating to the incidence of bronchiectasis post-infection with SARS. Importantly, those that do exist have reported similar incidences of this finding. A study comparing high-resolution computed tomography (HRCT) imaging of 25 SARS survivors showed that all admission CT scans were abnormal with evidence of ground-glass opacities or consolidation as is typically seen in cases of respiratory infection with coronaviruses. Bronchiectasis was not reported as an abnormality in any of these patients. Patients scanned between 2 and 27 days (median 9 days) after discharge showed disease progression and mild traction bronchiectasis was reported in 8 patients (32%) [9]. Another imaging study of 11 SARS survivors at 3, 6 and 84 months post-infection did not demonstrate features of bronchiectasis until 84 months follow up, where three out of 11 (27%) had evidence of traction bronchiectasis [10], highlighting the importance of long-term follow up to identify these cases.

The current evidence connecting COVID-19 and bronchiectasis is sparse; there is a lack of published data on follow up scans post-discharge due to the early phase of this pandemic and based on data from SARS it is likely that long-term follow up of more than 6 months will be required to identify established bronchiectasis. CT interpretations of a retrospective analysis of 120 patients from Wuhan city reported 14 cases of bronchiectasis (12%) [11]. Bronchiectasis was not noted as a comorbidity in the list of admission comorbidities, and unlikely to have been a significant feature at admission with COVID-19 and occurred de novo. Another study assessing HRCT in six COVID-19 patients in China reported mild bronchiectasis in one of these patients on admission (17%) [12]. This study is of course limited to its small data set, but is consistent with data of slightly larger studies and supports the possible link if larger studies are carried out and longer follow-up is explored. In a larger retrospective study detailing radiological findings in 81 patients with COVID-19, bronchiectasis was described in nine of the 81 patients (11%). The prevalence of bronchiectasis was higher in the groups who were followed-up at >2 weeks after symptom onset in comparison to those at <2 weeks [13], suggesting that it is less likely that these patients already had bronchiectasis at presentation. Furthermore, a retrospective study of 101 COVID-19 cases from four institutions in China, showed the majority of patients had typical radiological features of ground glass appearance and consolidation, but notably, 53 patients (52.5%) had traction bronchiectasis, similar to that seen post-SARS [14]. Traction bronchiectasis is a subtype of bronchiectasis whereby the bronchi are dilated secondary to mechanical traction from fibrosis of the adjacent lung parenchyma. It is therefore plausible that if severe COVID-19 results in fibroproliferative lung disease that traction bronchiectasis becomes evident. This may be compounded by lung injury secondary to invasive mechanical ventilation. How many of these cases will continue to have bronchiectasis following resolution of the interstitial pneumonitis is unknown, but dilated, or tortuous bronchi lose their ability to clear mucus effectively, and the structural lung disease may predispose to chronic cough or recurrent chest infections. Early recognition of this complication and appropriate treatment of airway inflammation or the underlying fibroproliferative process has the potential to reverse bronchiectasis and prevent longstanding poor health associated with established bronchiectasis.

Expert Opinion

At present, data describing CT findings in COVID-19 patients is rising but still very limited when it comes to post-hospital discharge follow-up. It is likely that conclusive information will only be available in a year once 6 and 12 months follow up data is published. Nonetheless, since there are links between COVID-19 risk factors, post-infective bronchiectasis and evidence of traction bronchiectasis cases following SARS, preliminary evidence suggests that due to the large numbers of individuals infected with SARS-CoV-2, bronchiectasis could be a possible common sequela and that we are likely to see an increase in bronchiectasis cases as a result of this pandemic. We therefore highlight a call to arms to identify bronchiectasis in survivors of COVID-19 and monitor patients long-term for chronic productive cough or recurrent respiratory tract infections so that appropriate preventative treatment to reduce exacerbations and improve quality of life is not delayed.

Declaration of interest

No potential conflict of interest was reported by the authors.