Background Microbiology Coronavirus related to SARS-CoV
Virion consists of:
Spike glycoprotein (S), which appears to be an important virulence factor
Vaccines may target either the full protein or only its distal receptor binding domain
Membrane protein (M)
Nucleocapsid protein (N)
Hemagglutinin esterase (He)
Envelope protein (E) Epidemiology Transmitted mostly by respiratory droplets, with some amount transmission via aerosols and little to no transmission via contact
First cases detected Dec 2019 related to likely exposure in wet market in Wuhan, Hubei, China, and declared a pandemic in 2020
Secondary household attack rate of 12-17% Risk Factors for Mortality Clinical Manifestations Incubation period 4 to 5 days (range 2 to 11 days), possibly as long as 14 days in some cases
Main presenting symptoms were fever and cough , followed by myalgia , fatigue , headache , dyspnea
Other symptoms include dyspnea , rhinorrhea , vomiting , diarrhea , anosmia /hyposmia
Lymphopenia is common, as is hypoalbuminemia, elevated D-dimer, CRP, LDH, AST/ALTViral load detectable before symptom onset and peaks around the time of symptom onset Pregnancy Please refer to a living systematic review on the topic
Slightly less reported fever and myalgias
Slightly more ICU admissions and mechanical ventilation
Risk factors included age, obesity, hypertension, and diabetes
With regards to the fetus, there were more preterm deliveries (6%) and more needed NICU admission (25%) Severity Mild: no oxygen
Moderate: supplemental oxygen
Severe: non-invasive mechanical ventilation
Critical: invasive mechanical ventilation Bacterial Coinfection Complications In critically ill patients:
Diagnosis PCR from NP swab
Highest sensitivity within 5 days of symptom onset, with decreasing sensitivity as the disease enters the immune-mediated phase
May be positive long after no longer infectious
Diagnostic accuracy of PCR by sample site (below) has a lot of heterogeneity among the studies
Sensitivity
Specificity
Upper Respiratory Samples
Oral
56
99
Nasal
76
100
NP
97
100
Nasal
95
100
Saliva
85
100
Mid-turbinate
100
100
Upper Versus Lower Tract
Upper respiratory tract
57
100
Lower respiratory tract
81
100
Single Versus Repeat Testing
Single test
71
100
Repeat testing
100
100
Serology (IgM and IgG)
Total antibodies have poor sensitivity (51%) in first week, and increases to about 90% by week 3 Management For patients no requiring supplemental oxygen, the focus is on supportive care
For patients requiring supplemental oxygen or with oxygen saturation less than 94%:
Dexamethasone 6 mg PO/IV daily for 10 days, which has a mortality benefitRemdesivir 200 mg PO once on day one followed by 100 mg PO daily for 5-10 days, which has not been shown to have a mortality benefit
Avoid hydroxychloroquine /chloroquine , lopinavir-ritonavir
Tocilizumab may be indicated if progressing despite usual care, still requiring oxygen and CRP ≥75 mg/L, per RECOVERY trialAnticoagulation A multiplatform RCT combined ATTACC, REMAP-CAP, and ACTIV-4a looked at therapeutic anticoagulation (compared to prophylactic)
Therapeutic anticoagulation with heparin derivatives, using the LMWH typical for the hospital at DVT/PE treatment doses
Duration 14 days, or until discharge if before 14 days
Helpful in moderately ill patients, regardless of D-dimer value
Potentially harmful in severely or critically ill patients Strongyloidiasis Prevention Infection Prevention and Control Healthcare Workers Awaiting results
If symptomatic, HCWs should be off work
If asymptomatic, HCWs may return to work while awaiting results, depending on the reason for testing and the staffing needs
Positive but asymptomatic: in exceptional circumstances, may return to work early Clearance Non-test based (preferred)
Asymptomatic: isolate for 10 days from swab
Mild to moderate symptoms in immunocompetent person: 10 days from onset of symptoms, as long as afebrile (without antipyretics) and clinically improving
Severe (i.e. ICU-level care) or immunocompromised: 20 days from onset of symptoms, as long as afebrile (without antipyretics) and clinically improving
Test based (alternative): 2 negative swabs at least 24 hours apart (if still positive, repeat in 3 to 4 days), as long as afebrile and clinically improving Further Reading References
^ Louise Lansbury, Benjamin Lim, Vadsala Baskaran, Wei Shen Lim. Co-infections in people with COVID-19: a systematic review and meta-analysis. Journal of Infection . 2020;81(2):266-275. doi :10.1016/j.jinf.2020.05.046 .
