Updated: July 6, 2023

MICROBIOLOGY

• Coronaviruses
  • Positive sense, single-stranded enveloped RNA virus belongs to the family Coronaviridae.
  • Coronavirus name is derived from the Latin corona, meaning crown. The viral envelope under electron microscopy appears crown-like due to small bulbar projections formed by the viral spike (S) peplomers. Neutralizing antibodies against the S-protein are believed to play an important role in protective immunity.
• This topic covers the novel coronavirus 2019, SARS-CoV-2.
• For discussion of other coronaviruses, see individual highlighted modules:
  • Coronavirus for common human respiratory coronavirus infections.
  • SARS for SARS-CoV-1 virus has not been known to circulate since 2002–2003.
  • MERS for the MERS-CoV virus, causing sporadic infections, mainly in the Arabian peninsula since 2012.
  • Coronaviruses also commonly infect birds and mammals, causing gastroenteritis and respiratory diseases.
• SARS-CoV-2 uncertainty exists regarding whether its emergence into human populations appears to be a zoonotic infection or related to release from a laboratory studying the virus.
  • Origin is uncertain, although bats are implicated as this virus is closely related by genetic analysis to bat SARS-like coronavirus (genus Betacoronavirus, subgenus Sarbecovirus). Circulating viruses similar to the Wuhan (ancestor strain) of SARS-CoV-2 has not yet been conclusively demonstrated in an intermediary animal reservoir. However, recent reports have suggested that raccoon dogs (Nyctereutes procyonoides) may be the case based on sampling in/near the Wuhan market. The alternate lab leak theory has its proponents, and a definitive origin may never be known.

CLINICAL

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

Epidemiology

• COVID-19 cases
  • The virus has established itself as a year-round respiratory pathogen.
    • U.S. Pubilc Health Emergency ceased in May 2023, similarly the WHO for a global health emergency.
    • June 2023, with ~ 6,000 hospitalizations per week in the U.S. and ~ 200 deaths.
  • The evolution of viral variants and subvariants has slowed due to significant global human immunity. However, reporting cases is less careful or absent in many countries due to antigen testing, which is not captured.
    • • Omicron appears at least more transmissible than Delta and the Delta variant and is 50-70% more transmissible than earlier variants, including Alpha.
        • This CDC genomic variant surveillance may track circulating Omicron sublineages in the US; XBB subvariants of multiple types dominate in the US (June 2023).
          • Includes NOWCAST projection and modeling of what may happen in real-time since data lags by 2-3+ weeks.
      • Severe infections remain more prevalent in the unimmunized or no prior infection with multiple risk factors and people with poor antibody responses to vaccines or infections.
• Risk groups
  • Older age, especially > 65 yrs, and people with comorbidities appear more likely to develop an infection with severe symptoms and be at risk for death.
    • Age gradient, with > 85 years highest; 81% of U.S. deaths are age > 65 years with 80x greater mortality risk than 18- to 29-year-olds.
    • CDC reports that 95% of COVID-19-related deaths have at least one comorbidity.
    • FDA and CDC have age ≥ 50 yrs as the substantial change in increased risk.
  • Risks (per CDC; see link for more complete details): as determined by types of studies, multiple risk factors increase risks further.
    • Comorbidities (alphabetical order): age ≥ 50 years, cancer, chronic kidney disease, COPD, chronic lung disease, dementia or other neurological conditions, diabetes (types 1 and 2), Down syndrome, HIV, immunocompromised people, mental health conditions (depression, schizophrenia), BMI ≥ 25 (so overweight or obesity), pregnancy, sickle cell or thalassemia, smoking (current or former), solid organ or blood stem cell transplant, stroke/CVA, substance use disorders, active TB.
      • Multiple comorbidities are additive in risk.
    • Racial, ethnic and socioeconomic factors also increased the risk for heightened mortality and poor outcomes due to disparities in and barriers to accessing care.
    • Children/Teens: generally at less risk for severe illness; however, underlying medical problems, if present, elevate risk.
      • Younger adults are also hospitalized in the U.S., reflecting increasing percentages in many states. These cases in the later phases of the pandemic account for an increasing percentage of cases.
      • 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 the 1–10 yr group; however, some studies show a higher risk of transmission than adults.
    • People in congregate settings with disabilities or chronic health problems have worse outcomes and face barriers to care.

Transmission

• Through respiratory droplets, aerosolization is possible (especially indoors/prolonged exposure, areas with poor ventilation). Acquisition from fomites is likely uncommon. Viruses are found in respiratory secretions and saliva.
  • Spread from a fomite; the risk is considered very low.
• Viral shedding by asymptomatic people may represent a subset of total infections, but uncertainty remains regarding how much they contribute to totals.
  • Viral shedding may antedate symptoms, usually two days.
  • Viral titers are highest in the earliest phases of infection, 1-2 days before the onset of symptoms, and then in the first 4-6 days of illness in patients without immunosuppression.
• SARS-CoV-2 continues to evolve rapidly due to the inherent infidelity of RNA viruses that generate random mutations and millions of daily infections.
  
  • Asymptomatically infected people who shed and spread are part of the explanation.
    • Not-ill people will not as carefully take measures to avoid transmission.
      • Some are super-spreaders, which may be due to inherent characteristics (e.g., their speech generates aerosol, loud speaking, etc.).
    • Mass gatherings enhance transmission, especially indoors in smaller spaces or with poor ventilation.
    • This is essentially the rationale behind universal mask use indoors when community rates are high.
  • Aerosol spread may contribute, especially in some settings.
    • The amount of airborne transmission frequency is debated, and evidence of viral RNA beyond the expected droplet range, especially indoors, if poor ventilation exists.
      • 6-ft distancing remains a routine social distancing recommendation but has largely not been followed in many settings where mitigation strategies are no long advocated; uncovered face/sneezes may generate partial aerosolization with some activities for greater distances.
  • 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 one cannot maintain social distancing, at least six feet.
  • Stool shedding is also described later in the disease, but uncertain what role, if any, that plays in transmission.
    • It appears to be a tool to predict outbreaks and changes in community viral contours.

Incubation period and viral shedding, isolation, quarantine or airborne isolation

1. Mean incubation with Omicron is 4.3 days, median 3-4d, range 2–14d.
2. Quarantine and Isolation: some local health departments and institutions may vary from CDC guidance.
   1. 1. Isolation: a term used if SARS-CoV-2 is infected with or without symptoms.
         1. If tested positive (antigen or PCR) regardless of vaccine status: isolate at home and from others x 5d after the onset of symptoms.
         2. End isolation after 5 full days if fever-free and not using antipyretics and symptoms improve.
            1. Per CDC, HCW now 7d or two negative serial antigen tests if < 10d.
         3. If severely ill or immunocompromised: isolate x 10d and consult your clinician before ending isolation.
         4. Wear a mask for 10 days inside your home and in public.
            1. Some people with immunity may yield infectious virus through days 10-14, longer if severely immunosuppressed.
         5. Avoid being around people who are at high risk.
      2. Quarantine: a term if potentially exposed.
         1. CDC no longer advises quarantine (Aug 2022) if entirely up to date on immunization.
         2. If you test negative by antigen testing, this correlates with either no infection or a low possibility for infectivity.
   2. Healthcare worker recommendations:
      1. The CDC updated guidance for HCW (9/23/22), reflecting longer carriage in many with infectious virus beyond five days.
         1. Quarantine: in most circumstances, regardless of vaccination status, asymptomatic workers and those who test negative do not need restrictions.
         2. Isolation
            1. HCW with mild to moderate disease (and not immunocompromised) may return to work if:
               • At least 7 days have passed since symptoms first appeared if a negative viral test* is obtained within 48 hours before returning to work (or 10 days if testing is not performed or if a positive test at day 5-7), and
               • At least 24 hours have passed since the last fever without the use of fever-reducing medications, and
               • Symptoms (e.g., cough, shortness of breath) have improved.
            2. HCW with severe/critical infection who are not immunocompromised may return to work if:
               • At least 10 days and up to 20 days have passed since symptoms first appeared, and
               • At least 24 hours have passed since the last fever without the use of fever-reducing medications, and
               • Symptoms (e.g., cough, shortness of breath) have improved.
               • The test-based strategy, as described below for moderately to severely immunocompromised HCP, can inform the duration of work restriction.
3. Viral shedding as an infectious risk
   • Occurs following recovery but does not appear to play a role in transmission in relatively healthy people >10d following the onset of infection (though some variants may be infectious longer, viral RNA may be detected long after for many weeks; hence, why repeated routine testing for negative SARS-CoV-2 RT-PCR not recommended).
   • It may not be so short for ill hospitalized patients or those with health problems. However, 20-28d is a conservative stance some hospitals use to remove airborne precautions rather than the two negative nucleic acid amplification tests (NAAT) rule.
     • Rare reports of cultivatable virus > 60 days, especially in severely immunocompromised patients.:
       • A low cycle threshold (CT), e.g., < 30 and usually < 25, may indicate an infectious virus is present.
         • However, difficult to compare results when different testing platforms are used.
4. Some accumulating data suggest that high viral inoculum may lead to an increased risk for disease severity.

Symptoms (in the unimmunized): note symptoms of Omicron infection may be milder, resembling a URTI, in both immunized and unimmunized, but still capable of producing a severe infection.

• Most common
  • Fever
  • Cough (dry)
  • Fatigue
• Less common
  • Myalgia
  • Pharyngitis (or other respiratory symptoms)
  • Headache
  • GI including diarrhea
  • Conjunctivitis
  • Loss of taste or smell
  • Rash (chilblains, discoloring on fingers/toes)
• Serious/warning symptoms
  • Shortness of breath
  • Chest pain/pressure
  • Confusion
  • Lethargy
  • Cyanosis

Disease spectrum

• Although severe COVID-19 is primarily a lower respiratory tract infection in the earlier phases of the pandemic, early and mild cases may have upper respiratory tract viral infection features, especially with Omicron and more so in breakthrough infections immunized.
• The information below represents knowledge before the Omicron variant.
• ~80% of infections are not severe, and patients recuperate without special treatment.
  • Especially true for children and younger adults, although the Omicron variants are prompting greater hospitalizations in younger populations.
• ~20% develop significant infection (higher risk if elderly or comorbidities). Percentages are derived from earlier in the pandemic and appear less in the Omicron-subvariant era.
  • ~15% require hospitalization.
  • ~5% require ICU care.
  • Lower percentages for those < 50 yrs, even with comorbidities.
• Overall mortality risk: varies widely between regions and countries, as well as the variant circulating. Omicron has less pathogenicity than Delta or Alpha variants, notably less pneumonia despite increased growth advantage and transmission.
  • Estimates are difficult as the number of asymptomatic and unreported infections, if known, would lower rates.
    • Both under- and over-reporting are possible, especially as home antigen testing or undiagnosed URIs are not reported.
    • Rates have changed over time.
    • U.S. COVID fatalities > 1 million, although attributable mortality is estimated to be higher, with more than 3 million deaths.
• For hospitalized patients with pneumonia, the disease course in people hospitalized with risk factors, especially older patients and those with comorbidities:
  • If unimmunized or without prior infection/SARS-CoV-2 antibodies, ~50% develop hypoxemia by day 8, but this figure is much less in the Omicron era, especially in immunized and boosted.
    • Severe illness and cytokine release syndrome appear to develop primarily 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, and d-dimer.
    • ARDS develops in 17–29% +/- multiorgan system failure.
  • Patients in the ICU often require mechanical ventilation with prone positions recommended if poor lung compliance; ECMO is used in some centers.
• Greater severity of illness was reported with combined influenza and SARS-CoV-2 infection.

SITES OF INFECTION

• Like many severe viral infections, a growing list of potential associations and complications.
• Progressive illness, including the hyperinflammatory phase, may cause a multi-organ system failure.
• Pulmonary
  • Pneumonia with characteristic ground-glass infiltrates, later with evolution to ARDS.
  • Co-infection with other viruses or superinfection with bacteria and molds (especially Aspergillus).
• GI
  • Some patients have nausea, vomiting, or diarrhea at the onset.
    • May herald more severe disease
  • The virus has been recovered from stool, but the significance is uncertain.
  • Liver: increased LFTs common
• CNS: encephalopathy is not uncommon, but true encephalitis (abnormal CSF and detection of the virus) appears rare.

TREATMENT

FOLLOW UP

• For the immunized, CDC issued guidance that 5d after onset, if symptoms have resolved or improved, people can leave isolation as long as wearing masks for days 5-10.
  • For healthcare personnel, CDC has revised this to 7 days or two serial negative antigen tests within 48h.
• Case fatality rates are highly variable in regions and different countries. Unclear why, and it may be multifactorial.
• Recovery from COVID-19 produces antibodies, but the response is heterogeneous, significantly lower in asymptomatic infected patients, and measurable responses such as antibody levels may diminish significantly in as little as 2–3 months. The protective immunity duration is unclear. T-cell responses are also likely critical.
• Quanrantine and Isolation: (CDC, updated 5/11/23):
  
  • Transmission to others correlated with viral load and was often highest when asymptomatic and in the first days after the onset of symptoms.
  • Serial viral cultures of infected patients (early in the pandemic and Delta/early Omicron) were found 61% positive after d6 of symptom onset; however, secondary household transmission occurred primarily in < 6d[4].
  • Advice for COVID-19 (+) patients remains self-isolation/quarantine:
    • 5d isolation at home, staying away from others (as this is the most infectious period).
    • After d5, wear a high-quality mask around others at home or in public.
• Long COVID, post-COVID Conditions
  • Wide range of symptoms that WHO defines as the continuation or development of new symptoms 3 months after the initial SARS-CoV-2 infection, with these symptoms lasting for at least 2 months with no other explanation.
  • Occurrence is greater in those who have had severe COVID-19.
  • Unimmunized and untreated people with risk factors appear more predisposed.
  • Common symptoms:
    • Fatigue (often post-exertional) interfering with usual activities
    • Brain fog, neurocognitive dysfunction
    • Dyspnea and chest pain
    • Headaches
    • Sleep problems
    • Depression or anxiety
    • Joint or muscle pain
  • Diagnosis and treatment: as the mechanism of disease is not understood, this impairs the ability to manage.
    • No current diagnostic tests secure the diagnosis, and some patients may lack a history of COVID-19. Alternatively, anchoring to COVID may be a bias that delays the investigation into other causes.
      • Studies are ongoing to understand the condition. Incidence estimates widely vary from < 5% to 20% or more.
    • Patient management currently needs to be individualized relating to patient complaints.
      • Often borrow from fibromyalgia or chronic fatigue syndrome literature.

OTHER INFORMATION

• Severe illness strikes the same populations at high risk for seasonal influenza complications (e.g., elderly, immunosuppressed, obese and those with comorbidities).
• The case fatality rate remains higher than seasonal influenza, especially in advanced elderly and those with multiple comorbidities, transplant patients.

Basis for recommendation

1. NIH COVID-19 Treatment Guidelines. https://www.covid19treatmentguidelines.nih.gov/ (last updated 4/20/2023, accessed 7/5/23)

   Comment: Comprehensive GL is revised regularly with updates. Recent additions include two studies suggesting the safety of using the protease inhibitor Paxlovid during pregnancy (similar to the HIV protease inhibitor experience.
   

2. Bhimraj A, et al. Infectious Diseases Society of America Guidelines on the Treatment and Management of Patients with COVID-19 [last updated 6/23/23, accessed 7/5/23]

   Comment: Regularly updated and generally in concert with the NIH GL. One central area where our JH guide differs is in convalescent plasma use, which we at JH believe has a role in early illness in hospitalized patients (< 3d) or in some severely immunosuppressed patients who cannot generate meaningful antibody responses and now has a more significant role that monoclonal antibodies are no longer available. The availability of high-titer convalescent plasma remains limited for many.
   

References

3. Xie Y, Choi T, Al-Aly Z. Association of Treatment With Nirmatrelvir and the Risk of Post-COVID-19 Condition. JAMA Intern Med. 2023.  [PMID:36951829]

   Comment: This cohort study suggests that those with at least one risk factor for COVID-19 had a reduced risk of ~ 25% for long COVID if they took the antiviral protease inhibitor.
   

4. Deyoe JE, Kelly JD, Grijalva CG, et al. Association of culturable-virus detection and household transmission of SARS-CoV-2 - California and Tennessee, 2020-2022. J Infect Dis. 2023.  [PMID:36705269]

   Comment: An elegant study including viral cultures, done first early in the pandemic and then later on, but not in a well-immunized population, found that while 61% remained with culturable virus ≥ 6 days after symptom onset, household transmission mainly occurred < 6d. This is in keeping that high viral load is a factor in viral transmission, often when people are asymptotic.
   

5. Senefeld JW, Franchini M, Mengoli C, et al. COVID-19 Convalescent Plasma for the Treatment of Immunocompromised Patients: A Systematic Review and Meta-analysis. JAMA Netw Open. 2023;6(1):e2250647.  [PMID:36633846]

   Comment: Many academic centers employ CP +/- other agents such as RDV for their immunodeficient, hospitalized COVID patients. This population has not been as well studied, and CP has been unfairly maligned due to negative trials in other populations who probably would not benefit due to late administration. This meta-analysis shows a mortality benefit, suggesting that some populations benefit from antibodies directed against the virus.
   

6. Sullivan DJ, Gebo KA, Shoham S, et al. Early Outpatient Treatment for Covid-19 with Convalescent Plasma. N Engl J Med. 2022.  [PMID:35353960]

   Comment: Though convalescent plasma is now limited by the FDA to patients who are immunosuppressed, this RCT of early administration of high-titer convalescent plasma showed a 54% reduction in hospitalization within 28d of symptom onset.
   

7. Hammond J, Leister-Tebbe H, Gardner A, et al. Oral Nirmatrelvir for High-Risk, Nonhospitalized Adults with Covid-19. N Engl J Med. 2022;386(15):1397-1408.  [PMID:35172054]

   Comment: Trial in unimmunized patients with mild-moderate COVID-19 found 87-88% reduction in hospitalization or death compared to placebo. The drug is relatively well-tolerated. Achilles heel is co-packaging with ritonavir to boost nirmtrelavir levels, the SARS-CoV-2 specific protease inhibitor. Ritonavir, with its suicide inhibitor impact on CYP3A4, knocks out many patients who are on meds such as tacrolimus. Need to check for drug interactions. Patients on statins can have the drug held for the 5-day course.
   

8. Jayk Bernal A, Gomes da Silva MM, Musungaie DB, et al. Molnupiravir for Oral Treatment of Covid-19 in Nonhospitalized Patients. N Engl J Med. 2022;386(6):509-520.  [PMID:34914868]

   Comment: It was disappointing that the efficacy fell to 30% from the preliminary 50% impact at reducing hospitalization or death in this study of mild-moderate COVID-19 in unimmunized patients. The drug has a clean slide effect profile. Much has been made of genotoxicity concerns, but the impact is not clear from a 5d course. Check for pregnancy in women of childbearing age. Notably, fewer deaths in the molnupiravir arm, but not statistically significant. Probably worthwhile in patients at high risk for disease progression, and at least in early 2022 is the easiest to procure and take compared to other outpatient medications for COVID-19.
   

9. RECOVERY Collaborative Group, Horby P, Lim WS, et al. Dexamethasone in Hospitalized Patients with Covid-19. N Engl J Med. 2021;384(8):693-704.  [PMID:32678530]

   Comment: Pragmatic trial, and also essential to note the extraordinarily high background mortality in the U.K at the time (~40%). 28-day mortality in the usual care group was highest in those patients receiving IMV (40.7%), intermediate in those receiving oxygen only (25.0%), and lowest among those who were not receiving respiratory support at randomization (13.2%). The most significant absolute reductions in 28-day mortality were seen in the sickest patients, and subgroup analysis suggests in those > 7d of symptoms that would correlate with the inflammatory phase. Dexamethasone improves 28d mortality compared to placebo in patients requiring IMV (NNT = 8.5) and those requiring oxygen therapy (NNT = 29). There was no benefit to patients not requiring oxygenation support and even a signal for harm.
   

10. Korley FK, Durkalski-Mauldin V, Yeatts SD, et al. Early Convalescent Plasma for High-Risk Outpatients with Covid-19. N Engl J Med. 2021.  [PMID:34407339]

    Comment: The use of high-titer convalescent plasma was not helpful in this trial of 511 patients who received it < 7d from the onset of symptoms. The average duration of symptoms in the active arm was 4 days (median IQR).
    

11. Joyner MJ, Carter RE, Senefeld JW, et al. Convalescent Plasma Antibody Levels and the Risk of Death from Covid-19. N Engl J Med. 2021;384(11):1015-1027.  [PMID:33523609]

    Comment: A subset of patients in the expanded access use of COVID-19 convalescent plasma found that high titer recipients who received units before critical illness had a lower risk of death than those with low titer plasma.
    

12. Libster R, Pérez Marc G, Wappner D, et al. Early High-Titer Plasma Therapy to Prevent Severe Covid-19 in Older Adults. N Engl J Med. 2021;384(7):610-618.  [PMID:33406353]

    Comment: Small but well-done double-blind RCT of patients > 65 yrs with mild COVID-18 and less than three days of symptoms. A total of 160 patients found that severe respiratory disease developed in 13 of 80 patients (16%) who received convalescent plasma and 25 of 80 patients (31%) who received placebo (relative risk, 0.52; 95% confidence interval [CI], 0.29 to 0.94; P = 0.03), with a relative risk reduction of 48%. A modified intention-to-treat analysis that excluded six patients with a primary end-point event before infusion of convalescent plasma or placebo showed a larger effect size (relative risk, 0.40; 95% CI, 0.20 to 0.81). No solicited adverse events were observed. The study is the best evidence that you need high titer units and early administration to have an effect.
    

13. Parr JB. Time to Reassess Tocilizumab's Role in COVID-19 Pneumonia. JAMA Intern Med. 2021;181(1):12-15.  [PMID:33079980]

    Comment: Helpful data synthesis of major tocilizumab trials. Data overall is mixed; there may be efficacy but nothing like that suggested from observational trials--at least for immunomodulatory monotherapy tocilizumab. The author suggests waiting for more RCT data to determine if the drug is helpful for COVID-19 patients. This paper included EMPACTA; however, not RECOVERY or REMAP-CAP, which has defined a difference between dexamethasone + tocilizumab vs. tocilizumab monotherapy.
    

14. Salama C, Han J, Yau L, et al. Tocilizumab in Patients Hospitalized with Covid-19 Pneumonia. N Engl J Med. 2021;384(1):20-30.  [PMID:33332779]

    Comment: Called a positive trial for tocilizumab, essential points are that 1) statistical significance only when the rate of progressing to mechanical ventilation is included (not just mechanical ventilation and death as hard endpoints) and 2) > 80% of patients also received dexamethasone, suggesting that the two drugs need to work together to help patients.
    

15. Beigel JH, Tomashek KM, Dodd LE, et al. Remdesivir for the Treatment of Covid-19 - Final Report. N Engl J Med. 2020.  [PMID:32445440]

    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. Final results are now available.
    

16. Kim D, Quinn J, Pinsky B, et al. Rates of Co-infection Between SARS-CoV-2 and Other Respiratory Pathogens. JAMA. 2020;323(20):2085-2086.  [PMID:32293646]

    Comment: A 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 one or more non–SARS-CoV-2 pathogens. Within the SARS-CoV-2 positive specimens, 24 (20.7%) were positive for one 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 of many standard respiratory viral illnesses. Finding a virus other than SARS-CoV-2 should not be grounds for concluding that COVID-19 is not present.
    

17. 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
    

18. WHO Rapid Evidence Appraisal for COVID-19 Therapies (REACT) Working Group, Sterne JAC, Murthy S, et al. Association Between Administration of Systemic Corticosteroids and Mortality Among Critically Ill Patients With COVID-19: A Meta-analysis. JAMA. 2020;324(13):1330-1341.  [PMID:32876694]

    Comment: Seven randomized trials included 1703 patients, of whom 647 died, 28-day all-cause mortality was lower among patients who received corticosteroids than those who received usual care or placebo (summary odds ratio, 0.66). Dexamethasone and hydrocortisone had a similar impact, while the single methylprednisolone trial had less effect on mortality.
    

19. Spinner CD, Gottlieb RL, Criner GJ, et al. Effect of Remdesivir vs Standard Care on Clinical Status at 11 Days in Patients With Moderate COVID-19: A Randomized Clinical Trial. JAMA. 2020;324(11):1048-1057.  [PMID:32821939]

    Comment: Though the open-label trial was cited as a reason to use 5-day instead of 10-d RDV for severe COVID-19, the fact that the 10-d course did worse without notably more side effects is concerning that the 5d data are perhaps not as solid. Also, the FDA cites this trial as a reason (along with ACTT-1) to expand RDV use to those hospitalized but not needing oxygen; however, NNT =~100, and limited patients not requiring oxygen at randomization are included.
    

20. Ai T, Yang Z, Hou H, et al. Correlation of Chest CT and RT-PCR Testing for Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 Cases. Radiology. 2020;296(2):E32-E40.  [PMID:32101510]

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

21. Giacomelli A, Pezzati L, Conti F, et al. Self-reported Olfactory and Taste Disorders in Patients With Severe Acute Respiratory Coronavirus 2 Infection: A Cross-sectional Study. Clin Infect Dis. 2020;71(15):889-890.  [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.
    

22. Kam KQ, Yung CF, Cui L, et al. A Well Infant With Coronavirus Disease 2019 With High Viral Load. Clin Infect Dis. 2020;71(15):847-849.  [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, well known for regular coronavirus infections, influenza and others.
    

23. 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;69(6):1002-1009.  [PMID:32213556]

    Comment: The paper suggests that some patients presented with GI symptoms as part of COVID-19, 11.4% of 651 in this study from Zhejiang 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.
    

24. Mizumoto K, Chowell G. Estimating Risk for Death from Coronavirus Disease, China, January-February 2020. Emerg Infect Dis. 2020;26(6):1251-1256.  [PMID:32168464]

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

25. Wölfel R, Corman VM, Guggemos W, et al. Virological assessment of hospitalized patients with COVID-2019. Nature. 2020;581(7809):465-469.  [PMID:32235945]

    Comment: A small but well-conducted study looks at 9 cases, with most patients on day 1 having mild or prodromal symptoms. Key findings include finding the 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 the stool. Viral RNA remained in the 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 proves that illness may also present as a routine upper respiratory tract infection without pneumonia or lower tract symptoms.
    

26. 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;368(6489):395-400.  [PMID:32144116]

    Comment: Although extraordinary measures may have slowed or stopped COVID-19 in China, questions remain about whether this is durable and at what cost to society. It may buy time, but effective drugs or vaccines remain in the future. 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."
    

27. 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;382(14):1370-1371.  [PMID:32163697]

    Comment: A retrospective look at 366 children hospitalized for respiratory illness. SARS-CoV-2 was 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.
    

28. 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;323(11):1061-1069.  [PMID:32031570]

    Comment: One of the initial significant reports of the Wuhan COVID-19 epidemic. In this series, the median age was 56 and slightly more men (54%) were 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%]).
    

29. Zhu N, Zhang D, Wang W, et al. A Novel Coronavirus from Patients with Pneumonia in China, 2019. N Engl J Med. 2020;382(8):727-733.  [PMID:31978945]

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

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