associated with more severe forms of the disease. By exploring the immunological responses, the reader will understand the deleterious effects of a maladaptive immune response to COVID-19 and how various pathways can be targeted for therapies such as immune modulation (for example, IL-6 inhibitors), as well as vaccine development (for example, spike protein). With COVID-19 infection, a variable pathological process occurs in the lung. In those who are critically ill, it is now well-established from post mortem examinations that the lungs have evidence of diffuse alveolar damage with lymphoid infiltration of the interstitium and capillary or arteriolar microthromboses. In those with less respiratory compromise, this is reflected in the lung tissue by lymphocytic-type pneumonia with atypical hyperplasia of type II pneumocytes. Describing the variety of patterns of lung injury helps respiratory teams appreciate the likely severity of the disease, the benefits of suggested therapeutics and the potential long-term consequences, such as lung fibrosis in those who have been ventilated for longer periods. Another fundamental chapter of this Monograph is the patient perspective, which presents the powerful narrative of a COVID-19 survivor [5]. They detail their hospital experience in the general ward as well as in the ICU. At the start of the pandemic, many advocated early intubation and some clinicians were reticent to consider high-flow oxygenation or noninvasive measures for respiratory support, partly due to the fear of aerosolisation of the COVID-19 virus. More recent observational studies have demonstrated the utility of high-flow oxygenation and perhaps even noninvasive therapy to help reduce the need for invasive ventilation [6]. Proning has been a central part of our supportive therapy for awake and ventilated patients, and thanks to trial data [7–11], we are now equipped with therapeutics [12]. The rapid response to the virus in terms of the design and swift implementation of large international clinical trials to ascertain the effects of differing therapeutics was a major accomplishment and success [13]. Barriers that prevented collaborative work disappeared, and respiratory scientists and clinicians around the world worked as one. Currently, we are able to offer: dexamethasone, which RCTs have shown to have mortality benefits remdesivir, an anti-viral drug that inhibits viral RNA transcription and tocilizumab and sarilumab, which are monoclonal antibodies that block the IL-6 receptor, thus instigating a reduction in pro-inflammatory cytokines [7–11, 14]. With the advent of large, adaptive platform trials, recommendations have been made pertaining to the role of therapeutic versus prophylactic anticoagulation in COVID-19 patients [15]. The suggestion is that therapeutic anticoagulation should be strongly considered in moderately unwell general ward patients with a low risk of bleeding. Patients receiving high-flow oxygenation, NIV or invasive ventilation should, conversely, be offered prophylactic anticoagulation. For those who survive COVID-19, there is emerging evidence of the persistence of diverse symptoms after the acute phase of the disease. These enduring symptoms may be respiratory in nature but many patients also suffer from extra-respiratory post-COVID sequelae. This chapter of the Monograph offers a comprehensive guide to post-COVID sequelae, together with the rationale and benefits of rehabilitation in this typically younger cohort of patients, in order to support their return to being productive members of society [16]. Predictably, the COVID-19 pandemic has had a detrimental effect on society, not only on the physical health of some of those significantly affected but also upon mental and economic x https://doi.org/10.1183/2312508X.10017521