Coronavirus COVID-19 (SARS-CoV-2)

Updated: August 5, 2020

MICROBIOLOGY

• Coronaviruses
  • Positive sense, single-strand enveloped RNA virus belonging to the family Coronaviridae.
  • Coronavirus name derived from the Latin corona, meaning crown. Viral envelope under electron microscopy appears crown-like due to small bulbar projections formed by the viral spike (S) peplomers.
• This topic covers the novel coronavirus 2019 (2019-nCoV) now referred to as SARS-CoV-2.
• For discussion of other coronaviruses, see individual highlighted modules:
  • Coronavirus for common human respiratory coronavirus infections.
  • SARS for the SARS-CoV virus, not known to circulate since 2002–2003.
  • MERS for the MERS-CoV virus, causing sporadic infections, mostly in the Arabian peninsula since 2012.
  • Coronaviruses also commonly infect birds and mammals causing gastroenteritis and respiratory infections.
• SARS-CoV-2 appears to have been a zoonotic infection that has adapted to humans.
  • Origin is uncertain although bats implicated as this virus most closely related by genetic analysis to bat SARS-like coronavirus (genus Betacoronavirus, subgenus Sarbecovirus). An intermediary, the scaled mammal pangolin, has also been invoked as a potential bridge for the jump to humans.

CLINICAL

• COVID-19 (novel COronaVIirus Disease-2019) is the disease, SARS-CoV-2 is the virus.

Epidemiology

• COVID-19 cases
  • Reported worldwide in all continents except Antarctica.
    • Declared a pandemic by the WHO. Unlikely this virus will disappear and may become part of the repertoire of respiratory viruses that infect humans regularly.
  • Real-time global reports available through Coronavirus COVID-19 Global Cases Dashboard by Johns Hopkins CSSE.
  • In U.S. States with high rates in the early phase of the pandemic, many have low rates now, although exceptions and outbreaks are occurring, e.g., California. Many other states not greatly impacted earlier are now experiencing high case loads, including rural regions.
    • Increased cases attributed to lack of cohesive public health recommendations, return to work, lack of social distancing/wearing face mask (especially younger adults).
• Risk groups
  • Older age, especially > 65 yrs and people with comorbidities appear more likely to develop an infection and severe symptoms and be at risk for death.
    • Males are more affected, especially with critical illness COVID-19.
  • Comorbidities:
    • Definite: cancer, chronic kidney disease, COPD, immunocompromise from solid organ transplant, obesity/BMI > 30, serious cardiovascular disease, sickle cell disease, type II diabetes mellitus
    • Possible increased risk (limited data): asthma (moderate-severe), CVA, cystic fibrosis, hypertension, immunocompromise from immunodeficiency/bone marrow transplant, neurological conditions (e.g., dementia), liver disease, pregnancy, pulmonary fibrosis, smoking, thalassemia, type 1 diabetes mellitus.
  • Younger adults are also being hospitalized in the U.S.
    • Adults 20–44 account for 20% of hospitalizations, 12% of ICU admissions.
  • In the U.S.:
    • Obesity appears to be emerging as a risk factor, BMI ≥ 30, in nearly half of hospitalized patients.
  • Blacks, Native Americans and Latinx appear to be hospitalized at rates greater than expected on a population basis.
  • Children appear less symptomatic with infection and less prone to severe illness.
    • Children < 1 yr at high risk for severe illness
    • Children 1–10 yrs: low risk of disease and transmission
    • Children 10–18 yrs: higher risk of disease compared to 1–10 yr group, however, higher risk of transmission in some studies than adults.
    • CDC suggests children with medically complex diseases including neurologic, genetic, metabolic conditions, or who have congenital heart disease are at higher risk for severe illness from COVID-19.

Transmission

Webinar Video: Important Trends in the Spread of COVID-19

• By respiratory droplets predominantly, but some aerosolization possible from speaking or singing > fomite. Virus found in respiratory secretions and saliva.
• Viral shedding by asymptomatic people may represent 30–60% of total infections, though some uncertainty remains regarding how much they contribute to totals.
  • Viral shedding may antedate symptoms by 1–2 days.
  • Viral titers are highest in the earliest phases of infection.
• Why widespread and rapid transmission occurs is not completely understood.
  • Asymptomatically infected people (an estimated 35% of cases per CDC) who shed and spread is a likely explanation.
    • People who are not ill will not as carefully take measures to avoid spread.
    • Mass gatherings especially indoors in smaller spaces or with poor ventilation appear to enhance transmission.
    • This is in large part the rationale behind universal mask use.
  • Aerosol spread appears possible in some settings.
    • Airborne transmission frequency is debated, evidence of viral RNA beyond expected droplet range especially indoors if poor ventilation exists.
      • Unclear if infectious, and may be due to droplets circulating further than 6 ft or partial aerosolization with some activities.
      • Some widely publicized evidence is based on experimental aerosolization rather than human studies.
    • To date, there has not been a well-documented outbreak traced to aerosol transmission at a distance (e.g., through HVAC ventilatory systems or airplanes).
  • Whether droplet or aerosol, concern for spreading by those ill or not ill but infected is the rationale for the universal wearing of masks while in public or if cannot maintain social distancing, at least six feet.
  • Stool shedding also described later in the disease, but uncertain what role, if any, that plays. Some researchers using as a tool to predict community outbreaks.

Incubation period and viral shedding

• Mean of 5–6 days, range 2–12
• For people quarantined, 14d observation recommended to exclude infection.
• Viral shedding
  • Occurs following recovery but does not appear to play a role in transmission in relatively healthy people 10–14d following the onset of infection.
  • In ill hospitalized patients or those with health problems, it may not be so short, but 28d is used by some hospitals to remove airborne precautions rather than the two negative nucleic acid tests (NAT) rule.
• Some suggest that high viral load may equate with disease severity, but studies to date have not standardized.

Symptoms

• May occur 2–14 d after exposure (most data are taken from hospitalized patients or presenting for emergency care, less clear about presenting symptoms for the less ill)
• Fever (44%–98%)
  • Range may be lower at initial hospital presentation or in the outpatient setting.
• Cough (46–82%, usually dry)
• Shortness of breath at onset (31%)
• Myalgia or fatigue (11–44%)
• Loss of taste or smell
  • Potential sign in early infection, but not unique to COVID-19 as may be seen with other viral infections

Less common symptoms:

• Pharyngitis
• Headache
• Productive cough
• GI symptoms including diarrhea, nausea, vomiting or abdominal pain
  • Have been described as a presenting symptom and potentially heralding more severe illness
• Hemoptysis
• Chest pressure or pain
• Confusion
• Cyanosis
• Skin changes (chilblains or COVID toes)

Disease spectrum

• Although severe COVID-19 illness is mostly a lower respiratory tract infection, early and mild cases may have features of upper respiratory tract viral infection.
• ~80% of infections are not severe, and patients recuperate without special treatment.
  • Especially true for children and younger adults
• ~20% develop respiratory complaints (higher risk if elderly or comorbidities).
  • 12–20% require hospitalization
  • ~2–4% require ICU care
• Overall mortality risk: 0.5–1.0% (influenza 0.1%), but higher with risk factors and age gradient (highest if > 85 yrs, e.g., 10–27%).
• For hospitalized patients with pneumonia, limited studies suggest the disease course:
  • ~50% develop hypoxemia by day 8
    • Severe illness and cytokine release syndrome appear to develop mostly within 5–10d after symptom onset in susceptible patients.
    • Markers of a severe infection include regular high fevers (>39°C), RR > 30, worsening oxygen requirements (4–6L nasal cannula), also elevated IL-6 levels (> 40–100), CRP, ferritin, d-dimer.
    • ARDS develops in 17–29%
  • Patients in the ICU often require mechanical ventilation with prone positions recommended if poor lung compliance; ECMO used in some centers.
• Critical Illness experience (Washington State)[11]
  • Small patient series (n = 21)
    • Age: 70 (mean)
    • Comorbidities: in 86%
    • Duration of symptoms: 3.5d (mean)
      • Admission to ICU within 24h of hospitalization: 81%
    • Nearly all had radiographic abnormalities at presentation.
      • Leukopenia: in 67%
    • Mechanical ventilation: in 71%
      • ARDS in 100% of those who required mechanical ventilation, most developed within 72h.
    • Most patients were not in shock, but 67% received vasopressors.
    • Cardiomyopathy: developed in 33%
      • Unclear if direct viral effect v. critical illness stress
    • Mortality: 67% (as of publication date)

SITES OF INFECTION

• Progressive illness including the hyperinflammatory phase may cause multi-organ system failure.
• Pulmonary
  • Pneumonia with characteristic ground-glass infiltrates, later with evolution to ARDS.
  • Co-infection with other viruses described
• GI
  • Some patients have nausea, vomiting, or diarrhea at the onset.
    • May herald more serious disease
  • The virus has been recovered from stool, but the significance is uncertain.
• CNS: encephalopathy not uncommon but true encephalitis (abnormal CSF and detection of the virus) appears rare.

TREATMENT

FOLLOW UP

• Case fatality rates highly variable in regions, different countries. Unclear why and may be multifactorial.
• Preliminary evidence in humans and SARS-CoV-2 infected rhesus macaques suggest that reinfection does not occur.
• Recovery from COVID-19 produces antibodies, but the response is heterogeneous, especially lower in asymptomatic infected patients, and measurable responses may diminish significantly in as little as 2–3 months. The protective immunity duration is unclear. T cell responses also likely important. Not yet clear what is required to prevent a second infection.
• Advice for COVID-19 (+) patients and self-isolation/quarantine: further details, CDC.
  • Inpatients:
    • Healthcare settings: no longer a requirement for 2 sequential negative COVID-19 RT-PCR tests before airborne precautions can be lifted, as viral RNA has been detected (so-called re-positives), for up to 12 weeks or longer.
    • CDC (7/17/20) changed from a testing alogrithm to a time-based assessment.
      • Except for rare situations, a test-based strategy is no longer recommended to determine when to discontinue Transmission-Based Precautions.
      • For patients with severe to critical illness or who are severely immunocompromised, Transmission-Based Precautions are extended to 20 days after symptom onset (or, for asymptomatic severely immunocompromised patients, 20 days after their initial positive SARS-CoV-2 diagnostic test).
  • Outpatients:
    • CDC (7/17/20 update), also time-based, no less than 10d after symptom onset.
      • Changed from “at least 72 hours” to “at least 24 hours” have passed since
        • The last fever without the use of fever-reducing medications.
        • Also changed from “improvement in respiratory symptoms” to “improvement in symptoms” to address expanding list of symptoms associated with COVID-19.
      • Patients who have impaired ability to make antibodies (e.g., immunosuppressed patients) are likely to shed virus longer.

OTHER INFORMATION

• Testing for viral RNA now may include asymptomatic in addition to symptomatic patients.
• Severe illness strikes much the same populations at high risk for complications of seasonal influenza (e.g., elderly, immunosuppressed, obesity and comorbidities).
• The case fatality rate is probably higher than seasonal influenza (≤0.1%) but may be lower than initially reported (~ 2–4%), but careful epidemiology surveys in progress; it may be different in some countries as social distancing interventions and other factors differ.
  • Current estimates suggest COVID-19 is ~6–12x worse than seasonal influenza but has a steep age gradient.

See also

• COVID-19: Are We Getting Ahead? (Webinar Series)

Basis for recommendation

1. Beigel JH, et. al. Remdesivir for the treatment of Covid-19--A preliminary report. N Engl J Med. May 22, 2020 [https://www.nejm.org/doi/full/10.1056/NEJMoa2007764]

   Comment: The ACTT1 results that showed improved LOS by 4 days in patients receiving RDV. The average duration of symptoms prior to enrollment was 9d median with a wide range. The key observation from data is that benefit was derived in patients who were started prior to mechanical ventilation, suggesting that the use of the drug earlier in the disease course has efficacy--consistent with its mechanism of action as an antiviral.
   

2. Bhimraj A, et al. Infectious Diseases Society of America Guidelines on the Treatment and Management of Patients with COVID-19 [last updated 6/25/20]

   Comment: Guidance endorses use of RDV
   Among hospitalized patients with severe* COVID-19, the IDSA panel suggests remdesivir over no antiviral treatment. (Conditional recommendation, Moderate certainty of evidence)
   Remark: For consideration in contingency or crisis capacity settings (i.e., limited remdesivir supply): Remdesivir appears to demonstrate the most benefit in those with severe COVID-19 on supplemental oxygen rather than in patients on mechanical ventilation or extracorporeal mechanical oxygenation (ECMO).
   Recommendation 9. Among patients with severe COVID-19 on supplemental oxygen but not on mechanical ventilation or ECMO, the IDSA panel suggests treatment with five days of remdesivir rather than 10 days of remdesivir. (Conditional recommendation, low certainty of evidence)
   Guidance endorses use of dexamethasone
   Among hospitalized patients with severe* COVID-19, the IDSA guideline panel suggests glucocorticoids rather than no glucocorticoids. (Conditional recommendation, moderate certainty of evidence)
   Remark: Dexamethasone 6 mg IV or PO for 10 days (or until discharge if earlier) or equivalent glucocorticoid dose may be substituted if dexamethasone is unavailable. Equivalent total daily doses of alternative glucocorticoids to dexamethasone 6 mg daily are methylprednisolone 32 mg and prednisone 40 mg.
   Recommendation 5. Among hospitalized patients with COVID-19 without hypoxemia requiring supplemental oxygen, the IDSA guideline panel suggests against the use of glucocorticoids. (Conditional recommendation, low certainty of evidence)
   *Severe illness is defined as patients with SpO2 ≤94% on room air, and those who require supplemental oxygen, mechanical ventilation, or ECMO.
   

3. NIH COVID-19 Treatment Guidelines. https://www.covid19treatmentguidelines.nih.gov/ (last updated 6/25/20, accessed 7/31/20)

   Comment: Most important drug recommendations below, but document also handles HCQ, CQ and other issues in care of patients with COVID-19.
   NIH panel recommends:
   Dexamethasone for mechanically ventilated patients with COVID-19 (A1 recommendation), and for those who require oxygen (B1). It is not recommended based on the RECOVERY trial for hospitalized COVID-19 patients who do not need oxygen (A1). Dose 6 mg/kg/d x 10d.
   Remdesivir for hospitalized patients with SpO2 ≤94% on ambient air (at sea level) or those who require supplemental oxygen (AI).
   The Panel recommends remdesivir for treatment of COVID-19 in patients who are on mechanical ventilation or extracorporeal membrane oxygenation (ECMO) (BI). Duration of Therapy in Patients with Severe COVID-19 Who Are Not Intubated 5d. For mechanically ventilated or ECMO, 10 d.
   There are insufficient data on the optimal duration of therapy for mechanically ventilated patients, patients on ECMO, or patients who have not shown adequate improvement after 5 days of therapy. In these groups, some experts extend the total remdesivir treatment duration to up to 10 days (CIII).
   Recommendation for Patients with Mild or Moderate COVID-19:
   There are insufficient data for the Panel to recommend for or against remdesivir for the treatment of patients with mild or moderate COVID-19.
   

4. Hanson KE. Infectious Diseases Society of America Guidelines on the Diagnosis of COVID-19, last updated 5/6/20, [accessed 7/31/20]. [https://www.idsociety.org/practice-guideline/covid-19-guideline-diagnostic...]

   Comment: Helpful guidance including the suggestion that lower tract specimens (if performed with a validated assay) may be more sensitive than the traditional nasopharyngeal swab, though the evidence is limited.
   

5. Horby P, et al. Effect of Dexamethasone in Hospitalized Patients with COVID-19: Preliminary Report, https://www.medrxiv.org/content/10.1101/2020.06.22.20137273v1 (accessed 7/31/20)

   Comment: Dexamethasone arm of the RECOVERY trial that supports 6mg/kg/d x 10 as a standard of care for severe COVID-19, especially those on mechanical ventilation due to the mortality benefit.
   In this trial, there was a trend toward mortality in those who do not require oxygen, so not recommended in this group usually with early infection. Some aspects of the RECOVERY trial deserve comment: the UK trial mortality was unusually high if the same benefit would be witnessed in North America is less clear. Also, patients with less than 7d of symptoms appeared to not benefit, suggesting that the during early phase of viral illness there is no impact or potential harm (similar to influenza) but the benefit is seen with the later hyperinflammatory phase. This trial was open-label, but mortality endpoint would tend to discount bias to a substantial degree.
   

References

6. Wang Y, Zhang D, Du G, et al. Remdesivir in adults with severe COVID-19: a randomised, double-blind, placebo-controlled, multicentre trial. Lancet. 2020;395(10236):1569-1578.  [PMID:32423584]

   Comment: Unimpressive trial, but the drug may have been given to late to too ill a population.
   N = 237 patients, halted
   Confirmed infection, 12d or fewer of symptoms, lung involvement
   Remdesivir 200 mg d 1 then 100 mg IV daily vs. placebo
   Findings:
   1. No clinical improvement (subgroup < 10d with trend)
   2. No difference in mortality (subgroup < 10d with trend)
   3. No effect on viral load in upper or lower respiratory tracts
   

7. Chinazzi M, Davis JT, Ajelli M, et al. The effect of travel restrictions on the spread of the 2019 novel coronavirus (COVID-19) outbreak. Science. 2020.  [PMID:32144116]

   Comment: Although extraordinary measures may have slowed or stopped COVID-19 in China, questions remain whether this is durable and at what cost to society? It may buy time but effective drugs or vaccines remain in the far future it seems. Authors suggest "the travel quarantine of Wuhan delayed the overall epidemic progression by only 3 to 5 days in Mainland China, but has a more marked effect at the international scale, where case importations were reduced by nearly 80% until mid-February. Modeling results also indicate that sustained 90% travel restrictions to and from Mainland China only modestly affect the epidemic trajectory unless combined with a 50% or higher reduction of transmission in the community."
   

8. Mizumoto K, Chowell G. Estimating Risk for Death from 2019 Novel Coronavirus Disease, China, January-February 2020. Emerg Infect Dis. 2020;26(6).  [PMID:32168464]

   Comment: An early report and these typically have higher rates of infection due to concentrated, very ill patients than later in epidemics. Authors estimate of the risk for death in Wuhan reached values as high as 12% in the epicenter of the epidemic and ≈1% in other, more mildly affected areas. The elevated death risk estimates are probably associated with a breakdown of the healthcare system.
   

9. Liu W, Zhang Q, Chen J, et al. Detection of Covid-19 in Children in Early January 2020 in Wuhan, China. N Engl J Med. 2020.  [PMID:32163697]

   Comment: A retrospective look at 366 children hospitalized for respiratory illness. SARS-CoV-2 detected only in 6 (1.6) of patients. Only 1 of the COVID children required ICU care. Of the COVID patients, fever and cough were common and four had pneumonia.
   

10. Cao B, Wang Y, Wen D, et al. A Trial of Lopinavir-Ritonavir in Adults Hospitalized with Severe Covid-19. N Engl J Med. 2020.  [PMID:32187464]

    Comment: This trial did not yield benefits when given in hospitalized patients with c19. Whether the drug would work if administered earlier is unclear, but has low in vitro activity against this virus compared to HIV.
    

11. Arentz M, Yim E, Klaff L, et al. Characteristics and Outcomes of 21 Critically Ill Patients With COVID-19 in Washington State. JAMA. 2020.  [PMID:32191259]

    Comment: Most notable finding is the high rate of cardiac complications that is unclear whether directly viral or related to critical illness. As this is a small series, further reports are needed to confirm.
    

12. Shen C, Wang Z, Zhao F, et al. Treatment of 5 Critically Ill Patients With COVID-19 With Convalescent Plasma. JAMA. 2020.  [PMID:32219428]

    Comment: A small study of 5 patients who required mechanical ventilation who appeared to benefit from convalescent plasma containing neutralizing antibodies, though also received methylprednisolone and putative antiviral therapies directed against SARS-CoV-2 infection. Authors suggest that many parameters improved including in the 4 ARDS patients.
    

13. CDC COVID-19 Response Team. Severe Outcomes Among Patients with Coronavirus Disease 2019 (COVID-19) - United States, February 12-March 16, 2020. MMWR Morb Mortal Wkly Rep. 2020;69(12):343-346.  [PMID:32214079]

    Comment: US experience to date differs from China’s experience in that a higher proportion of hospitalizations are among the not elderly.
    

14. Bourouiba L. Turbulent Gas Clouds and Respiratory Pathogen Emissions: Potential Implications for Reducing Transmission of COVID-19. JAMA. 2020.  [PMID:32215590]

    Comment: Wading into the aerosol v. droplet debate, the suggestion that forceful uncovered sneezes may cause infectious droplets to go beyond the 6 ft range currently advised by the CDC. This concern has prompted universal mask wear for HCWs, but also for the general public. There may be people who are not ill and therefore sneeze or cough, asymptomatic shedding and dispersing virus.
    

15. Jin X, Lian JS, Hu JH, et al. Epidemiological, clinical and virological characteristics of 74 cases of coronavirus-infected disease 2019 (COVID-19) with gastrointestinal symptoms. Gut. 2020.  [PMID:32213556]

    Comment: Paper suggests that some patients presented with GI symptoms as part of COVID-19, 11.4% of 651 in this study from Zheijiang University in Hangzhou. A caveat is their definition of GI included nausea only in addition to diarrhea and vomiting as they only needed one of the three to qualify for GI symptoms. They also suggested that patients who had GI had more severe COVID infection.
    

16. Giacomelli A, Pezzati L, Conti F, et al. Self-reported olfactory and taste disorders in SARS-CoV-2 patients: a cross-sectional study. Clin Infect Dis. 2020.  [PMID:32215618]

    Comment: Authors report on patients in earlier phases of COVID-19 infection, 20 (33.9%) reported at least one taste or olfactory disorder and 11 (18.6%) both. This is not unique though as other viral respiratory infections may also cause these symptoms.
    

17. Lescure FX, Bouadma L, Nguyen D, et al. Clinical and virological data of the first cases of COVID-19 in Europe: a case series. Lancet Infect Dis. 2020.  [PMID:32224310]

    Comment: Series of only five patients from France; however, the descriptions of three potential phenotypes may offer insights into different viral- and Immuno-pathogenesis. 1. Paucisymptom patient: nasopharyngeal high viral titer (and virus in feces), 2. Symptoms then decompensation (~day 10, respiratory decompensation): low viral titer compared to earlier in nasopharyngeal samples and 3. Clinical progression/death: high viral titers in upper and lower respiratory samples plus persisting viremia.
    

18. Guo L, Ren L, Yang S, et al. Profiling Early Humoral Response to Diagnose Novel Coronavirus Disease (COVID-19). Clin Infect Dis. 2020.  [PMID:32198501]

    Comment: Authors used a nucleocapsid-based antibody for the detection of antibodies against SARS-CoV-2. IgM and IgA antibodies were found 5 days (IQR 3-6) after symptom onset, while IgG was detected on 14 days (IQR 10-18). Positive responses overall were seen as IgM 85.4%, IgA 92.7% and IgG 77.9% respectively. Considering both confirmed and probable cases, the positive rates of IgM antibodies were 75.6% and 93.1%, respectively. The detection efficiency by IgM ELISA is higher than that of qPCR method after 5.5 days of symptom onset. The positive detection rate is significantly increased (98.6%) when combined IgM ELISA assay with PCR for each patient compare with a single qPCR test (51.9%).
    

19. Long QX, Tang XJ, Shi QL, et al. Clinical and immunological assessment of asymptomatic SARS-CoV-2 infections. Nat Med. 2020.  [PMID:32555424]

    Comment: 37 asymptomatic individuals displayed longer viral shedding, less cytokine generation and less serological responsiveness.
    Asymptomatic 93.3% (28/30) and 81.1% (30/37) had less IgG and neutralizing Abs
    ‒In comparison , 96.8% (30/31) and 62.2% (23/37) of symptomatic patients.
    -40% asymptomatic seronegative vs. 12.9% of the symptomatic group during convalescence
    §Protective immunity may not be long-lived
    

20. Boulware DR, Pullen MF, Bangdiwala AS, et al. A Randomized Trial of Hydroxychloroquine as Postexposure Prophylaxis for Covid-19. N Engl J Med. 2020.  [PMID:32492293]

    Comment: HCQ did not appear to prevent illness consistent with COVID-19 in patients with moderate or high-risk exposure to the virus when started within four days of the exposure.
    

21. Zhu N, Zhang D, Wang W, et al. A Novel Coronavirus from Patients with Pneumonia in China, 2019. N Engl J Med. 2020.  [PMID:31978945]

    Comment: An early report includes electron microscopy photomicrographs as well as sequence analysis of what is now termed COVID-19 disease and SARS-2-CoV virus.
    

22. Zhou P, Yang XL, Wang XG, et al. A pneumonia outbreak associated with a new coronavirus of probable bat origin. Nature. 2020.  [PMID:32015507]

    Comment: Authors have sequenced what is now termed SARS-2-CoV. Its genome 79.5% sequence identify to SARS-CoV. Furthermore, it was found that 2019-nCoV is 96% identical at the whole-genome level to a bat coronavirus.
    

23. Bajema KL, Oster AM, McGovern OL, et al. Persons Evaluated for 2019 Novel Coronavirus - United States, January 2020. MMWR Morb Mortal Wkly Rep. 2020;69(6):166-170.  [PMID:32053579]

    Comment: People evaluated as per this report in the US mostly were those with a history of travel/contacts from Wuhan City, China which is the apparent epicenter of this epidemic. Of 210 people, 148 (70%) had travel-related risk only, 42 (20%) had close contact with an ill laboratory-confirmed 2019-nCoV patient or PUI, and 18 (9%) had both travel- and contact-related risks. Eleven of these persons had a laboratory-confirmed 2019-nCoV infection. Given reports now around the globe, it is unclear if testing only those with potential links to China is prudent, but the current availability of test kits from the CDC likely precludes wider testing until either FDA-approved or EUA approval is given to current commercially available respiratory panels to include COVID-19.
    

24. Benvenuto D, Giovanetti M, Salemi M, et al. The global spread of 2019-nCoV: a molecular evolutionary analysis. Pathog Glob Health. 2020.  [PMID:32048560]

    Comment: Strain analysis to date of COVID-19 suggests that they are very similar to bat SAR-like coronavirus.
    

25. Wang D, Hu B, Hu C, et al. Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus-Infected Pneumonia in Wuhan, China. JAMA. 2020.  [PMID:32031570]

    Comment: One of the initial major reports of the Wuhan COVID-19 epidemic. In this series, the median age was 56 and slightly more men (54%) affected. Predominant symptoms include fever, fatigue and dry cough. Leukopenia was seen in ~70%. Thirty-six patients (26.1%) were transferred to the intensive care unit (ICU) because of complications, including acute respiratory distress syndrome (22 [61.1%]), arrhythmia (16 [44.4%]), and shock (11 [30.6%]).
    

26. Ai T, Yang Z, Hou H, et al. Correlation of Chest CT and RT-PCR Testing in Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 Cases. Radiology. 2020.  [PMID:32101510]

    Comment: Chest CT shows early ground-glass infiltrates which may offer speedier "diagnosis" than PCR studies in an epidemic setting as a first finding if molecular assays not readily available.
    

27. Kam KQ, Yung CF, Cui L, et al. A Well Infant with Coronavirus Disease 2019 (COVID-19) with High Viral Load. Clin Infect Dis. 2020.  [PMID:32112082]

    Comment: No surprise, here an infant sheds high levels of the virus but is without symptoms. Children are well known "vectors" of viral infection often without significant disease is well known for regular coronavirus infections, influenza and others.
    

28. Wölfel R, Corman VM, Guggemos W, et al. Virological assessment of hospitalized patients with COVID-2019. Nature. 2020.  [PMID:32235945]

    Comment: A small but well-conducted study looking at 9 cases with most patients on day 1 having mild or prodromal symptoms. Key findings include finding virus in upper respiratory tissues with no difference between nasopharyngeal and oropharyngeal speeding which was very high during the first week of illness, but not in stool. Viral RNA remained in sputum beyond the resolution of symptoms. Seroconversion occurred by day 7 in 50% of patients but by day 14 in 100%. Despite the knowledge gained about viral kinetics, this paper offers proof that illness may also present as a routine upper respiratory tract infection without pneumonia or lower tract symptoms.
    

29. Grein J, Ohmagari N, Shin D, et al. Compassionate Use of Remdesivir for Patients with Severe Covid-19. N Engl J Med. 2020.  [PMID:32275812]

    Comment: Early experience with this antiviral in severe COVID-19 illness, found that there was an improvement in 36 of 53 patients (68%). Seven patients (13%) died; mortality was 18% (6 of 34) among patients receiving invasive ventilation and 5% (1 of 19) among those not receiving invasive ventilation. The lack of a control arm makes this number difficult to understand whether the drug is helpful. As authors indicate, there is a need to await RCT data.
    

30. Kim D, Quinn J, Pinsky B, et al. Rates of Co-infection Between SARS-CoV-2 and Other Respiratory Pathogens. JAMA. 2020.  [PMID:32293646]

    Comment: Series of 1217 specimens analyzed for respiratory viruses, found 116/1217 specimens (9.5%) were positive for SARS-CoV-2 and 318 (26.1%) were positive for 1 or more non–SARS-CoV-2 pathogens. WIthin the SARS-CoV-2 positive specimens, 24 (20.7%) were positive for 1 or more additional pathogens. The most commonly detected co-infections were rhinovirus/enterovirus (6.9%), respiratory syncytial virus (5.2%), and non–SARS-CoV-2 Coronaviridae (4.3%). This report yielded higher viral co-pathogen rates than earlier COVID-19 studies, but similar to the co-infection rates seen with many standard respiratory viral illnesses. Importantly, this means that finding a virus other than the SARS-CoV-2 should not be grounds for concluding that COVID-19 is not present.
    

31. Chow EJ, Schwartz NG, Tobolowsky FA, et al. Symptom Screening at Illness Onset of Health Care Personnel With SARS-CoV-2 Infection in King County, Washington. JAMA. 2020.  [PMID:32301962]

    Comment: Syndromic screening that used fever and respiratory symptoms failed to detect SARS-CoV-2 infection (often at high titer) in 17% of HCWs presenting for assessment. While limited testing has forced decisions to screen people at a higher likelihood of infection, the wide range of potential COVID-19 infection means that some may unknowingly work and spread the virus. This no doubt is one reason the virus has spread so rapidly.
    

32. Kissler SM, Tedijanto C, Goldstein E, et al. Projecting the transmission dynamics of SARS-CoV-2 through the postpandemic period. Science. 2020.  [PMID:32291278]

    Comment: These models examine the potential impacts of whether there is short or longer-term immunity to SARS-CoV-2 or seasonality to the virus. These factors will play into whether there is a resurgence of the virus. Additional factors such as social distancing, therapeutic drugs and vaccines will also play a role.
    

33. Grasselli G, Zangrillo A, Zanella A, et al. Baseline Characteristics and Outcomes of 1591 Patients Infected With SARS-CoV-2 Admitted to ICUs of the Lombardy Region, Italy. JAMA. 2020.  [PMID:32250385]

    Comment: A large critical care experience derived from Northern Italy had 1591 patients who 68% had 1 comorbidity and 82% were male. Mortality as of the 3/25/20 writing date was 26%.
    

34. Liu Y, Ning Z, Chen Y, et al. Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospitals. Nature. 2020.  [PMID:32340022]

    Comment: An entry into the PRO potential for routine aerosolization of SARS-CoV-2. Viral RNA (unclear if infectious) found in toilet areas but not in ventilated isolation words. Levels also seen in areas prone to crowing including medical staff areas.
    

35. Borba MGS, Val FFA, Sampaio VS, et al. Effect of High vs Low Doses of Chloroquine Diphosphate as Adjunctive Therapy for Patients Hospitalized With Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection: A Randomized Clinical Trial. JAMA Netw Open. 2020;3(4):e208857.  [PMID:32339248]

    Comment: High dose CQ suggested to contribute to mortality. 440 patients, 81 were enrolled (41 [50.6%] to a high-dosage group and 40 [49.4%] to low-dosage group). Enrolled patients had a mean (SD) age of 51.1 (13.9) years, and most (60 [75.3%]) were men. Older age (mean [SD] age, 54.7 [13.7] years vs 47.4 [13.3] years) and more heart disease (5 of 28 [17.9%] vs 0) were seen in the high-dose group. Viral RNA was detected in 31 of 40 (77.5%) and 31 of 41 (75.6%) patients in the low-dosage and high-dosage groups, respectively. Lethality until day 13 was 39.0% in the high-dosage group (16 of 41) and 15.0% in the low-dosage group (6 of 40). The high-dosage group presented more instances of QTc interval greater than 500 milliseconds (7 of 37 [18.9%]) compared with the low-dosage group (4 of 36 [11.1%]). Respiratory secretion at day 4 was negative in only 6 of 27 patients (22.2%).
    

36. Chen T, Wu D, Chen H, et al. Clinical characteristics of 113 deceased patients with coronavirus disease 2019: retrospective study. BMJ. 2020;368:m1091.  [PMID:32217556]

    Comment: Patients in this Chinese retrospective study were older (median 68 yrs), male (73%) and had cardiovascular disease, including hypertension. While ARDS was common, acute cardiac injury and heart failure were also felt to contribute to high mortality.
    

37. Cheng Y, Wong R, Soo YO, et al. Use of convalescent plasma therapy in SARS patients in Hong Kong. Eur J Clin Microbiol Infect Dis. 2005;24(1):44-6.  [PMID:15616839]

    Comment: SARS paper that may inform COVID-19 infection. Benefit from convalescent plasma for treatment suggested by earlier discharge.
    

38. Gritti G, Raimondi F, Ripamonti D, et al. Use of siltuximab in patients with COVID-19 pneumonia requiring ventilatory support, https://www.medrxiv.org/content/10.1101/2020.04.01.20048561v1 (accessed 4/5/20)

    Comment: Unpublished preprint, using an anti-IL6 mab, in 21 patients with advanced COVID-19 pneumonia or ARDS. Following administration, 33% (7/21) improved, 43% (9/21) stabilized without identifiable change, and 24% (5/21) worsened. This uncontrolled study suggests that if such a drug is helpful for cytokine release syndrome from COVID-19, it may be more difficult to improve the sickest, i.e., ill the longest and with most lung damage.
    

39. Emergency Use Authorization (EUA) for emergency use of remdesivir for the treatment of hospitalized 2019 coronavirus disease (COVID-19) patients. U.S. Food and Drug Administration. May 1, 2020. [https://www.fda.gov/media/137564/download]

    Comment: EUA by the FDA, distribution federally controlled--unclear how much supply available. The drug remains investigational and is not FDA-approved.
    

40. Mehra MR, et al. Hydroxychloroquine or chloroquine with or without a macrolide for treatment of COVID-19: a multinational registry analysis. Lancet. May 22, 2020. [https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31180-6...]

    Comment: Though observational data though with ~96,000, another report implicating HCQ or CQ in patients ill with COVID-19 with toxicities, mainly cardiac, with no apparent signal of benefit.
    

41. Xu X et al. Effective Treatment of Severe COVID-19 Patients with Tocilizumab. Unpublished study. 2020 [http://chinaxiv.org/abs/202003.00026]

    Comment: Unpublished, a not yet peer-reviewed report from China on 21 patients in China hospitalized with COVID-19 and received tocilizumab. Most patients had a marked improvement in oxygen needs within 24h of IL6R mab administration. This suggests that interruption of a key cytokine might reverse the "storm" that appears to cause ARDS and further organ injury in a subset of patients.
    

42. Interim Infection Prevention and Control Recommendations for Patients with Confirmed Coronavirus Disease 2019 (COVID-19) or Persons Under Investigation for COVID-19 in Healthcare Settings. U.S. Centers for Disease Control and Prevention. [https://www.cdc.gov/coronavirus/2019-ncov/infection-control/control-recomm...]
43. Interim U.S. Guidance for Risk Assessment and Public Health Management of Healthcare Personnel with Potential Exposure in a Healthcare Setting to Patients with Coronavirus Disease 2019 (COVID-19). U.S. Centers for Disease Control and Prevention. [https://www.cdc.gov/coronavirus/2019-ncov/hcp/guidance-risk-assesment-hcp.html](accessed 6/26/20, last updated 7/31/20]

    Comment: Contact tracing has been shortened from 10d to 2d, for operational reasons, and based on data suggesting lower viral shedding in asymptomatic individuals.