WLA VA:COVID19

Introduction

• Disease name = COVID-19
• Virus = SARS-CoV-2 (previously 2019-nCoV

Virology

• Coronaviruses are a common human pathogens (discovered in the1960s to cause the common cold).
  • During epidemics, they are the cause of up to one-third of community-acquired upper respiratory tract infections in adults; may cause diarrhea in infants and children as well)
• SARS-CoV-2 is a novel coronavirus (a new strain not previously identified in humans)
  • Likely primary source = bats
  • A betacoronavirus in the same subgenus as the severe acute respiratory syndrome (SARS) virus
  • Receptor-binding gene region is very similar to that of the SARS coronavirus (uses angiotensin-converting enzyme 2 [ACE2] for cell entry)
  • Middle East respiratory syndrome (MERS) virus, another betacoronavirus, appears more distantly related
• Viral survival time of SARS-CoV-2:
  • Stainless steel: persists for 3 hours (or longer)
  • Underscores the importance of environmental cleaning / disinfection
    • Cleaning gets rid of the proteins that would interfere with a disinfectants effectiveness
  • Note: studied in a simulated lab environment. Lab virions not covered in protein and mucus and other things that would mimic real life and that could prolong survival

Basic Epidemiology/Infectivity Data

• Expected patient outcomes (from data so far):
  • 80% have mild symptoms
  • 15% have severe disease requiring hospitalisation
  • 5% require mechanical ventilation
• Case fatality rate (CFR) = 2-4% (from Hubei data)
  • SARS ~ 10%
  • MERS ~ 35%
  • Seasonal flu ~ 0.1-0.2%
  • 1918 Pandemic Influenza ~ 2-3%
• R0 = 2.2 - 4.2
  • Where R0 = expected number of secondary cases produced by a single typical infection in a susceptible population (basic reproductive rate)
  • R0 for seasonal flu ~ 1.3
  • R0 for pandemic flu ~ 1.5-1.8
• Incubation: 5 days (median); range of 2-14 days
• Serial interval duration = 7.5 days
  • Serial interval refers to the time from illness onset in successive cases in a transmission chain

Clinical Findings

• At onset: fever, dry cough, myalgias, fatigue, shortness of breath
  • Fever and cough start early, SOB noted about 9 days into illness
  • Fever not present in all adults (less common in vulnerable populations)
  • Less common: cough with sputum, sore throat, headache, congestion, GI symptoms
• Most common complications: pneumonia, ARDS (avg 8 days from onset, 20% of patients in China)
  • Decompensation risk occurs during 2nd week of illness
• Risk factors: older adults, underlying conditions (lung disease, heart disease, diabetes)
  • Children: milder disease (see Children)
  • Pregnant patients: don’t appear to be at increased risk of infection or adverse outcomes (limited data - see Pregnant Women)

Laboratory Findings

• Lymphopenia most common in critically ill; mildly elevated ALT, AST; normal pro-calcitonin on admission
  • Elevated d-dimer and severe lymphopenia are associated with increased mortality
  • RT-PCR is currently test of choice for confirming cases
    • Test kit availability is currently limited as of mid March
    • Consider influenza/viral respiratory panel to identify alternative diagnoses
      • Although co-infection is possible

Imaging

• XRay:
  • Portable CXR preferred in PUI to prevent spread of infection
  • May be normal in early disease
  • Typical pattern is peripheral patchy ground glass opacities (GGO)
  • More opacities correlates with worse disease
  • GGOs may coalesce and appear as infiltrates
• CT:
• Many have normal imaging early on (so CDC DOES not recommend CT for diagnostic purposes at this time)
  • CT (86%) more sensitive than CXR (59%) for detecting GGOs
  • Radiopaedia COVID-19 Resources (https://radiopaedia.org/articles/covid-19)
  • From the American College of Radiology (3/11/20): “Generally, the findings on chest imaging in COVID-19 are not specific, and overlap with other infections, including influenza, H1N1, SARS and MERS. Being in the midst of the current flu season with a much higher prevalence of influenza in the U.S. than COVID-19, further limits the specificity of CT.”
• Reinfection (after recovery from COVID19): unclear if possible
  • Limited data. Unlikely to be reinfected shortly after but unknown about later on

General Prevention Recommendations

• Exercise general infection precautions
  • Person-to-person transmission occurs with close contact (6 feet)
    • Direct contact with mucous membranes or respiratory droplets
    • Indirect: cough —> secretions left on surface —> 2nd person touches surface secretions and touches face & mucous membranes
  • Avoid touching your face (try it, it’s not easy)
  • Frequent Handwashing
    • Alcohol based hand sanitizer
    • Diligent hand wasing
      • 20 seconds minimum
      • Image shows commonly forgotten areas: thumb (ulnar aspect), fingertips, WRIST (Borrowed from WHO Hand Hygiene for Healthcare)
  • Wear a mask if you develop respiratory symptoms (fever, cough, rhinorrhea, congestion) to prevent spread
• Avoid unnecessary travel
• Stay home if symptomatic
  • Home care does not mean being out in the parks with other groups of people
  • Contact your supervisor: due to expected HCW shortages, minor symptoms may be allowed to continue working with adequate PPE to prevent infection spread

Precautions For Healthcare Workers

PPE Bottom Line: Per CDC and LADPH (3.12.20)

• “Can collect specimens (e.g., nasopharyngeal swabs) for COVID-19 observing standard, contact, and droplet precautions including eye protection in a normal examination room with the door closed”
• No airborne isolation required (unless aerosol-generating procedure)

Transmission

• Simply walking into a room is NOT a recognized risk of transmission. Must make contact with respiratory droplet (directly or indirectly)
• Masks: MOST IMPORTANT utility is to put on the coughing individual
  • Research clearly demonstrates it decreases shedding of infectious material in the environment
  • This is more effective than HCWs wearing masks prophylactically to prevent catching the infection when not actually performing close contact patient care
• How long to shut a patient room down after a COVID patient is in there?
  • It’s not about the risk of contracting the infection but about the ability to clean room safely without respiratory protection precautions by the cleaner
  • 30-40 minutes usually sufficient (for most modern facilities) as long as no aerosol-generating procedure performed (longer, time not clearly stated at this time)
    • Most modern rooms designed to have 12 air exchanges per hour
    • Ventilation symptoms vary. So, older / fewer exchanges per hour => more time.

PPE Guidelines

• EVERY PATIENT CONTACT: Respiratory droplet precautions. Contact precautions also recommended but if gowns in short supply consider reserving for aerosol-generating procedures
  • Droplet = surgical mask, eye protection
  • Contact = gown and gloves
  • Technique:
    • Mask donning (often incorrectly done):
      • Wash hands BEFORE touching mask
      • Grip mask by loops/bands/ties only
      • Coloured portion typically faces outward
      • Mold / pinch the stiff edge to the shape of your nose
      • Pull the bottom of the mask over your mouth AND chin
      • Make sure you are up to date with fit testing
    • Mask removal:
      • Wash hands BEFORE touching mask
      • Only make contact with the loops/bands/ties. DON’T TOUCH THE MASK ITSELF!
• For AEROSOL GENERATING procedures: airborne precautions (N95/PAPR)
  • Due to higher risk of aerosolizing droplets-- infection itself doesn’t seem to be spread via airborne route)
  • Aerosol generating procedures (avoid when possible)
    • Bag-valve mask (BMV)
    • CPAP/BiPAP
    • Intubation
    • Nebulizer administration (COMMONLY FORGOTTEN) - use MDI instead. E.g. 8-12 MDI puffs instead of albuterol 2.5-5mg INH.
    • Bronchoscopy
    • Chest PT

PPE Shortage/Limiting Usage Guidelines

In case of PPE shortage or in an attempt to save on PPE supplies, the following guidelines were approved by CDC 3/13/20

• Same respirator can be worn for multiple serial patient contacts (e.g. in between successive COVID/PUI (patients under investigation) without exchanging respirator. Therefore, in between each patient:
• No need to change mask or eye protection
• BUT need to change gown and gloves
• Respirator reuse possible? Higher risk because of having to touch the mask and either self-inoculate or transmit to another patient (e.g. wear it for a patient, then you remove, and then you put it back on)
• If you must do this because of limited supplies, don and doff properly and perform proper hand hygiene in between
• CDC / NIOSH will allow certain N95s to be used beyond manufacture-designated shelf life
  • See list of appropriate models here (manufactured between 2003-2013)
• N95 Reuse? Probably okay to re-use same N95 during an 8 hour shift as long as no tears or visible contamination. Store facedown in labeled re-sealable bag/container.
  • Based on non peer reviewed reports from Washington State

Healthcare Worker Monitoring

• Every HCW should be keeping a thermometer at home
• Self-monitor BID (and especially before work). Facilities should screen their HCW prior to shifts.
• If symptomatic, notify supervisor.
• If febrile, STAY HOME.
• If other symptoms, discuss with supervisor / clinical experts. Due to expected HCW shortages, minor symptoms may be allowed to continue working with adequate PPE to prevent infection spread