Since the outbreak of COVID-19 illness began in China, health professionals are sharing information widely to manage this pandemic. In this article we review common clinical characteristics associated with COVID-19 infection and risk factors for mortality. We relate new knowledge regarding duration of COVID-19 virus shedding. We also share what’s been learned about the ability of the coronavirus to survive on different surfaces.
Clinical Characteristics of COVID-19
Guan et. al.1 extracted data regarding 1099 patients with confirmed COVID-19 from 552 hospitals in 30 provinces, autonomous regions, and municipalities in China through January 29, 2020. The median age of the patients was 47 years; sex breakdown was 41.9% female/ 58.1% male. The most common symptoms were fever (43.8% on admission and 88.7% during hospitalization) and cough (67.8%). However: the absence of fever in COVID-19 is more frequent than in SARS-CoV (1%) and MERS-CoV infection (2%), so these patients may be missed if the surveillance case definition focuses on fever detection.
The incubation period was defined as the interval between the potential earliest date of contact of the transmission source and the potential earliest date of symptom onset (i.e., cough, fever, fatigue, or myalgia). The median incubation period was 4 days.
Of 975 chest CT scans that were performed at the time of admission, 86.2% revealed abnormal results. The most common patterns on chest CT were ground-glass opacity (56.4%) and bilateral patchy shadowing (51.8%).
Lymphocytopenia was present in 83.2% of the patients.
Disease severity was categorized as non-severe in 926 (84.3%) patients and severe in 173 (15.7%) patients. Patients with severe disease were older than those with non-severe disease by a median of 7 years. Patients with severe disease also had more prominent laboratory abnormalities (including lymphocytopenia and leukopenia) than those with non-severe disease.
Among the overall population, 23.7% had at least one coexisting illness (e.g., hypertension and chronic obstructive pulmonary disease). The presence of coexisting illness was more common among patients with severe disease than among those with non-severe disease (38.7% vs. 21.0%).
Risk factors for death with COVID-19 infection
Zhou et. al.2 published a retrospective, multicentre cohort study which explores the risk factors associated with in-hospital death. Data for examination was compiled from the medical records of 191 patients from Jinyintan and Wuhan Hospitals in Wuhan, China. Patients who died or were discharged between Dec 29, 2019 and Jan 31, 2020 were included in their study. The median age of the patients was 56 years; sex breakdown was 72 (38.0%) female/119 (62.0%) male. Of these 191 patients, 137 (71.7%) were discharged and 54 (28.3%) died in hospital.
Researchers chose lymphocyte count, D-dimer, Sequential Organ Failure Assessment (SOFA score), coronary heart disease, and age as the five variables for their multivariable logistic regression model. (The SOFA score is considered to reflect the state and degree of multi-organ dysfunction.) Researchers compared this data between survivors and non-survivors.
Of the 191 patients, 48% of patients had a comorbidity, with hypertension being the most common (30% patients), followed by diabetes (19% patients) and coronary heart disease (8% patients). Lymphocytopenia occurred in 36 of the 137 survivors (26%) and in 41 of the 54 non-survivors (76%). We have also described the link between of COVID-19 and the heart elsewhere.
Odds of in-hospital death increased with older age, a higher SOFA score, and D-dimer greater than 1 μg/mL on admission.
COVID-19 and co-morbidities
Based on their experience in Wuhan Tongji hospital, Wang et. al.3 recommend a triaging system to inform management strategies. “Type A” patients mainly suffer from pneumonia, and require basic treatment such as antivirals, antibiotics, oxygen therapy and glucocorticoids. “Type B” patients suffer from both pneumonia as well as comorbidities. Treatment for underlying cardiovascular, liver, or kidney disease, or malignant tumours must be provided in addition to treatment of the pneumonia. Finally, “Type C” patients are critically ill. Patients may be categorized as Type C if management for Type A patients proves unsatisfactory. Aggravation or deterioration of Type A or B patients can also result in classifying them as Type C patients. Multiple organ failure can result from either scenario. In Type C patients, Wang et. al. recommend the implementation of protective measures such as mechanical ventilation, glucocorticoids, antivirals, symptomatic treatment, and anti-shock therapy. They believe that early classification can result in earlier implementation of the effective treatment protocol. They also caution that deaths resulting from original comorbidities must not be attributed to COVID-19.
COVID-19 transmission and survival on surfaces
It is important to know the duration of viral shedding, in order to inform recommendations regarding patient isolation. Zhou et. al.2 report that the shortest observed duration of viral shedding among survivors was 8 days, whereas the longest was 37 days (median duration of 20 days). In non-survivors, the virus was continuously detectable until death.
Van Doremalen et al. 4 investigated the aerosol and surface stability of the COVID-19 virus:
- Aerosol: 3+ hours
- Copper: no viable virus was measured after 4 hours
- Cardboard: no viable virus was measured after 24 hours
- Plastic and stainless steel: viable virus was detected up to 72 hours after application to these surfaces
This team concludes that aerosol and surface (fomite) transmission of SARS-CoV-2 is plausible, as COVID-19 can remain viable and infectious in aerosols for hours and on surfaces for days.
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Author: Kelly Schoonderwoerd
Original articles:
- Guan et al. N Engl J Med. 2020 Feb 28.
- Zhou et al. Lancet. 2020 Mar 28;395(10229):1054-1062.
- Wang et al. Lancet. 2020 Mar 21;395(10228):e52.
- van Doremalen et al. N Engl J Med. 2020 Mar 17.
