Clinical characteristics of COVID-19

Detailed epidemiological information on laboratory-confirmed cases reported to The European Surveillance System (TESSy) are published in ECDC weekly COVID-19 surveillance report.

Figures presented, by country and for the EU/EEA and the UK overall, cover aspects including: the age-distribution of symptoms; age- and age-sex specific risk of hospitalisation, severe hospitalisation and death; country and age-specific distributions of time delays in disease progression, such as the duration from symptom onset to outcome; and the proportion of cases with reported underlying health conditions. Data from TESSy is not provided in the sections below since the most up-to-date information is available online.

Pathology and pathogenesis

Histologic findings from the lungs include diffuse alveolar damage similar to lung injury caused by other respiratory viruses, such as MERS-CoV and influenza virus. A distinctive characteristic of SARS-CoV-2 infection is vascular damage, with severe endothelial injury, widespread thrombosis, microangiopathy and angiogenesis [187].

Symptoms and signs

An Observational study of 1 420 patients with mild or moderate disease indicated that the most common symptoms were headache (70.3%), loss of smell (70.2%), nasal obstruction (67.8%), cough (63.2%), asthenia (63.3%), myalgia (62.5%), rhinorrhea (60.1%), gustatory dysfunction (54.2%) and sore throat (52.9%). Fever was reported by on 45.4% [188]. The latest International Severe Acute Respiratory and Emerging Infections Consortium (ISARIC) reported on 25 849 hospitalised cases of COVID-19 across a broad clinical spectrum. The five most common symptoms at admission were history of fever, shortness of breath, cough, fatigue/malaise, and confusion (N=25 849) [189]. An analysis of data from 4 203 patients mostly from China identified fever, cough and dyspnea (80.5%, 58.3% and 23.8%, respectively) as the most common clinical symptoms, and hypertension, cardiovascular disease and diabetes (16.4%, 12.1% and 9.8%, respectively) as most common comorbidities [190]. A study among 20 133 hospitalised patients from acute care hospitals in England, Wales and Scotland identified clustering of symptoms with three common clusters: one respiratory symptom cluster with cough, sputum, shortness of breath, and fever; a musculoskeletal symptom cluster with myalgia, joint pain, headache, and fatigue; a cluster of enteric symptoms with abdominal pain, vomiting, and diarrhoea [191]. Twenty nine per cent (5 384/18 605) of patients presented with gastrointestinal symptoms on admission, mostly in association with respiratory symptoms, while 4% of patients presented with only gastrointestinal symptoms. Olfactory and gustatory dysfunction have been identified as common symptoms with a 52.73% pooled prevalence across 10 studies with a total sample size of 1 627 patients from North America, Europe and Asia [192]. Similarly, altered taste sensation was found among 49.8% of COVID-19 patients in a pooled analysis of five studies with 817 patients [193].

Severity

According to data from the ISARIC COVID-19 database, 18%of hospitalised patients (4 752) were admitted to an ICU or high dependency unit (HDU), with a mean duration of stay of 9.7 days and a median of 7 (SD: 9.3 days) (n=3 458) [189]. Of these, 1 567 died, 1 106 are still in hospital,1 591 have recovered and been discharged and outcome records were missing for 488, as of 19 May 2020 [189]. In China, hospitalisation has occurred in 10.6% of reported cases [194]. A systematic review and meta-analysis reported pooled rates of ICU admission, acute respiratory distress syndrome (ARDS) and mortality of 10.9%, 18.4% and 4.3%, respectively, for 4 203 patients [190].

Median length of stay in ICU has been reported to be around 7 days for survivors and eight days for non-survivors though evidence is still limited [35,195-197].On 5 June 2020, the UK’s Intensive Care National Audit and Research Centre reported 8 533 (of 9 623) patients in critical care, of whom 3 615 patients have died and 4 918 have been discharged alive from critical care with a length of stay in ICU of 11 days for survivors and nine days for non-survivors (interquartile range (IQR) 4–24 days for survivors and 5–15 days for non-survivors) [198]. In a systematic review and meta-analysis of 11 studies [199], a significantly lower incidence of severe or critical disease was found in healthcare workers (HCW), compared to the incidence of severe or critical disease among all positive patients. Similarly, mortality was found to be significantly lower among HCWs than among all COVID-19 patients [199].

Complications of COVID-19 infection

The major complication of severe COVID-19 infection is acute respiratory distress syndrome (ARDS) presenting with dyspnoea and acute respiratory failure that requires mechanical ventilation. In addition to respiratory sequelae, severe COVID-19 has been linked to cardiovascular sequelae, such as myocardial injury, arrhythmias, cardiomyopathy and heart failure [200], acute kidney injury often requiring renal replacement therapy [201,202], neurological complications such as encephalopathy [203], and acute ischemic stroke. Encephalitis has been reported in rare cases [204]. Severe COVID-19 appears to be  associated with coagulopathy presenting as thrombosis in various organs [205-207] and it is proposed that SARS-CoV-2 causes lesions to endothelial cells that line the blood vessel particularly in the lungs, causing the vessels to leak and blood to clot which then triggers an inflammation throughout the body and fuels ARDS [208]. Among 184 COVID-19 cases admitted to ICUs in the Netherlands receiving standard thromboprophylaxis, 31% developed thrombotic complications, mainly venous thromboembolism (27%) or arterial thrombosis (2.7%) [209]. Both large vessels as well as small vessels are affected with manifestations ranging from pulmonary embolism to purpuric lesions on the extremities. In autopsies of COVID-19 cases in São Paulo, Brazil, a variable number of small fibrinous thrombi in small pulmonary arterioles of lung parenchyma was observed, in addition to exudative/proliferative diffuse alveolar damage [210].

From mid-April 2020, several countries affected by the COVID-19 pandemic reported cases of children who were hospitalised in intensive care units due to a rare paediatric inflammatory multisystem syndrome (PIMS) [211-213]. The presenting signs and symptoms are similar to Kawasaki disease (KD) and toxic shock syndrome (TSS). A possible temporal association with SARS-COV-2 infection has been hypothesised because some of the children that were tested for SARS-CoV-2 infection were either positive by PCR or serology. These children had prolonged fever, abdominal pain and other gastrointestinal symptoms (50-60%) as well as conjunctivitis, rash, irritability and in some cases, shock, usually of myocardial origin. Some respiratory symptoms could be present and dyspnoea was usually correlated with concurrent shock [211,212,214,215]. The WHO proposed a preliminary case definition to follow-up this newly identified complication [216].

 

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