COPD is a major cause of morbidity and mortality worldwide and carries a huge and growing economic and social burden. Telemedicine might allow the care of patients with limited access to health services and improve their self-management. During the COVID-19 pandemic, patient's safety represents one of the main reasons why we might use these tools to manage our patients. The authors conducted a literature search in MEDLINE database. The retrieval form of the Medical Subject Headings (Mesh) was ((Telemedicine OR Tele-rehabilitation OR Telemonitoring OR mHealth OR Ehealth OR Telehealth) AND COPD). We only included systematic reviews, reviews, meta-analysis, clinical trials and randomized-control trials, in the English language, with the selected search items in title or abstract, and published from January 1st 2015 to 31st May 2020 (n ¼ 56). There was a positive tendency toward benefits in tele-rehabilitation, health-education and self-management, early detection of COPD exacerbations, psychosocial support and smoking cessation, but the heterogeneity of clinical trials and reviews limits the extent to which this value can be understood. Telemonitoring interventions and cost-effectiveness had contradictory results. The literature on teleconsultation was scarce during this period. The non-inferiority tendency of telemedicine programmes comparing to conventional COPD management seems an opportunity to deliver quality healthcare to COPD patients, with a guarantee of patient's safety, especially during the COVID-19 outbreak.

Less than 5% of the patients needed to be referred to do in-person visits. Telemedicine is an already validated tool. 1-4 The COVID-19 pandemic allowed us to implement telehealth-focused processes to provide safe and convenient patient care, and both patients and allergists seem willing to continue to use it. 5 M. Morais-Almeida and C. S. Sousa participated in study design and conception and drafted the manuscript. All authors provided critical review of the manuscript and approved the final draft for publication.

We carefully read the recently published research letter “Is asthma protective of COVID‐19?” by Carli et al. 1 with great interest. Important topics for asthma patients during the coronavirus disease 2019 (COVID‐19) pandemic were discussed, including that until recently there was limited evidence that patients with chronic respiratory disorders are at lower risk of being infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS‐CoV‐2) or becoming severely ill.

Dyspnea is reported in a minority of patients affected by coronavirus disease 2019 (COVID-19). Even patients with pneumonia can present hypoxemia without any respiratory distress, a phenomenon known as “silent” or “happy hypoxemia”. During the current pandemic there were only a few studies conducted on this subject and these were quite heterogeneous. Therefore, the prevalence of “silent hypoxemia” varied substantially. While studies did not show a clear tendency of “silent hypoxemia” to poorer outcomes compared to hypoxemia presenting with dyspnea, several showed that patients with “silent hypoxemia” are not protected from poor outcomes either. There is a need for a uniform definition of “silent hypoxemia”, in order to better guide clinicians and investigators. More studies are needed to shed light on the mechanisms of “silent hypoxemia”, as well as its presentation and influence in the disease's progression and outcomes, so as to better assist physicians in the care of COVID-19 patients.

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