neca-COVID-19-transmission.pptx

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COVID-19 Transmission, Prevention, and Control

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COVID-19 transmission and infection prevention/control strategies
Matthew Simon, MD, MS
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Disclosures
"This presentation [is/was] supported by the Health Resources and Services Administration (HRSA) of the U.S. Department of Health and Human Services (HHS) as part of an award totaling $3,960,119 with no percentage financed with nongovernmental sources. The contents are those of the author(s) and do not necessarily represent the official views of, nor an endorsement, by HRSA, HHS or the U.S. Government."

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Disclosures continued
Dr. Simon has reported his spouse receives supported/ contracted research from Novartis and does not intend to discuss off-label or investigational use of products or services.
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Objectives
Review current global, national and local epidemiology of COVID-19
Recognize emerging data on SARS-CoV-2 transmission
How does transmission occur?
When does transmission occur?
How long can someone transmit the virus?
Discuss current infection prevention and control strategies
Healthcare worker personal protective equipment
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COVID-19 global summary
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Accessed 5/31/20 https://covid19.who.int/
May 31, 2020
Total cases
New cases
Total deaths
New deaths
CFR
Global
5,939,234
115,226
367,255
5,050
6.2%

Increase in global cases driven by outbreaks in Americas
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Accessed 5/31/20 https://covid19.who.int/

COVID-19 US summary
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May 31, 2020
Total cases
New cases
Total deaths
New deaths
CFR
US
1,761,503
23,553
103,700
915
5.9%
https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/cases-in-us.html
https://www.nytimes.com/interactive/2020/world/coronavirus-maps.html
New York, California, Illinois >100,00 cases and 31 states >10,000 cases
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Current COVID-19 hotspots in Southeastern, Southcentral, Western US
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https://www.nytimes.com/interactive/2020/world/coronavirus-maps.html

In NYS and NYC, marked decline in cases, but transmission has not fully abated
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May 31, 2020
Total cases
New cases*
Total deaths
(confirmed)
New deaths*
CFR
New York State
370,770
941
23,959
77
6.4%
New York City
200,830
546
16,882
17
8.4%
https://covid19tracker.health.ny.gov/views/NYS-COVID19-Tracker
https://www1.nyc.gov/site/doh/covid/covid-19-data.page
https://www.nytimes.com/interactive/2020/us/new-york-coronavirus-cases.html
* Due to delays in reports recent day may be incomplete

Novel coronaviruses emerge from animal reservoirs
Wit Nature Review Micro 2016

Wit Nature Review Micro 2016
Spillover events: bats intermediate host humans
SARS-CoV-2 ???

Transmission dynamics of SARS-CoV2
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Ro ~2-3
Average number of secondary infections arising from a single case
Incubation period 2-14 days
Median ~5 days
Attack rate
Household contacts 3-10%
Other contacts ~1%
Case clusters associated w/ gatherings
Cruise ships
Business conferences
Choir practice
Religious gatherings
Fitness classes

https://www.bloomberg.com/opinion/articles/2020-03-05/how-bad-is-the-cor... https://www.who.int/publications-detail/report-of-the-who-china-joint-mi...(covid-19)
Burke RM MMWR. 2020; 69 (9); H; ammer L MMWR 2020; 69(19) https://wwwnc.cdc.gov/eid/article/26/8/20-0633_article
Risk varies by type, duration, preventive measures, possibly viral load of source patient

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Transmission-based precautions
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https://www.cdc.gov/infectioncontrol/basics/transmission-based-precautio...

How is SARS-CoV-2 transmitted?
Respiratory droplets are primary mode of transmission
WHO, CDC, IDSA consensus
Requires close (3-6 feet) face to face contact
Relative importance of other modes of transmission is controversial/unclear
Contact
Airborne???
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Pan, M et al Journal of Applied Microbiology 127 (6) 2019
https://www.cdc.gov/coronavirus/2019-ncov/hcp/infection-control.html
https://www.who.int/news-room/commentaries/detail/modes-of-transmission-...
https://www.idsociety.org/practice-guideline/covid-19-guideline-infectio...

Respiratory droplets produced by breathing, talking and coughing contain particles of varied sizes.
large droplets (>5 micron) settle on surfaces close to the source patient
small particles (<5 micron) can remain suspended and travel long distances
Transmission of COVID-19
There is strong clinical and epidemiological evidence that the predominant mode of spread of COVID-19 is via respiratory droplets (produced during speaking, coughing, sneezing etc.):
Directly during close face-to-face contact (within ~1.5 m) by exposure of the face (and then mucosae of mouth, nose or eyes) OR
Indirectly by touching surfaces or fomites contaminated by respiratory droplets and then touching the face

Release of virus in respiratory secretions through coughing, speaking, sneezing
Close direct contact with unprotected mucous membrane exposure
It may be possible that a person can get COVID-19 bytouching a surface or object that has the virus on itand then touching their own mouth, nose, or possibly their eyes. This is not thought to be the main way the virus spreads, but we are still learning more about how this virus spreads.
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Turbulent gas cloud model of respiratory emissions
Aerosol/droplet dichotomy is oversimplification
Turbulent gas cloud contains and traps droplets of a continuum of sizes
Temperature, humidity, forward-momentum within cloud allow potential pathogen dispersion of longer distances up 23-26 feet
No direct evidence for SARS-CoV-2
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Bourouiba L JAMA 2020; 323(18)
?Quantity, viability of virus in droplets/aerosols needed for infection

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SARS-CoV-2 cultured from air and surfaces in experimental conditions
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"Viable/live" virus detected up to ~3 hours through artificial machine aerosol generator
Variable environmental surface stability
Copper up to 4 hours
Cardboard up to 24 hours
Steel and plastic up to 72 hours

Van Doremalen N Engl J Med. 2020; 382:1564-

Clinical evidence for other modes of transmission is limited
Air sampling in patient environment mixed results
Some studies of have detected viral RNA, but not live virus
Hospital room environment can be contaminated with viral RNA
Viral RNA not detected following routine cleaning/disinfection
Pattern of spread of COVID-19 supports large respiratory droplets as primary mode
Ro
Attack rate in household and close contacts
Absence of routine transmission in small enclosed community spaces (i.e. aircrafts)
Unrecognized cases where healthcare workers had high risk exposure to aerosol generating procedures using contact/droplet precautions did not result in transmission
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Ong S JAMA 2020:323(16)
Cheng VC Infect Control Hosp Epi 2020. 41(5); Ng K. Annals of Intern Med. 2020; 172 (11)
Liu Y et al Nature 2020 https://www.idsociety.org/practice-guideline/covid-19-guideline-infectio...
Bed rail, chair, sink, window in room, door handle, toilet bowl
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CDC recommended PPE for routine care of COVID-19 patients
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https://www.cdc.gov/coronavirus/2019-ncov/hcp/using-ppe.html

Comparison of N95 respirator and surgical face mask
N95
Tight fitting seal
Blocks/filters 95% of 0.3 micron test particles
Filtration capabilities exceed those of surgical facemask if properly fitted
Surgical facemask
Loose fitting
Physical barrier between nose and mouth to block large droplets, splashes
Does not block very small particles
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https://www.fda.gov/medical-devices/personal-protective-equipment-infect...

Large study of N95 vs. medical masks to prevent respiratory illness in healthcare workers
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Multi-center cluster randomized trial in 137 outpatient locations over 4 years
5180 outpatient/ER healthcare personnel (HCP)
Randomized to wear N95 vs medical masks when within 6 feet of patient with respiratory illness
Primary Outcome: Incidence of lab-confirmed influenza
Secondary outcomes: Incidence of confirmed/unconfirmed respiratory illnesses
Radonovich Jr LJ. JAMA. 2019;322(9):
No significant difference

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https://www.nytimes.com/2020/06/01/health/masks-surgical-N95-coronavirus... Chu DK et al Lancet 2020
Systematic review and meta-analysis
44 observational studies across 16 countries and 6 continents
Effect of physical distancing, face masks, eye protection
Risk of transmission of SARS, SARS-CoV-2 and MERS
Adjusted odds ratio

Physical distancing, face masks, eye protection all highly protective against transmission
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Chu DK et al Lancet 2020

Varying PPE recommendations from public health authorities
Organization
N95 preferred
Facemask recommended*
N95 or surgical mask (no preference)
US CDC
X
WHO
X
IDSA
X
European CDC
X
Australian Department of Health
X
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*N95 recommended for aerosol-generating procedures

Donning and Doffing PPE
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https://www.cdc.gov/hai/pdfs/ppe/PPE-Sequence.pdf

PPE donning and doffing video resources
New England Journal of Medicine
https://www.nejm.org/doi/full/10.1056/NEJMvcm2014809
CDC
https://www.cdc.gov/coronavirus/2019-ncov/hcp/using-ppe.html

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CDC facial hairstyle guidelines and respirator fit (seriously!)
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https://www.cdc.gov/niosh/npptl/images/infographics/FacialHairWmaskLG.jpg

PPE conservation/optimization strategies
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Understand inventory, supply chain and utilization rate
Crisis/Contingency capacity
Administrative controls
Extended use or reuse
N95 respirators, eye protection
Use of surgical mask over N95 to prevent surface contamination
Decontamination of N95 respirators
Hydrogen peroxide vapor
Ultraviolet germicidal irradiation
Moist heat

https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/index.html
https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/burn-calculat...
https://www.fda.gov/medical-devices/emergency-situations-medical-devices...
Contingency capacity: measures may change daily standard practices but may not have any significant impact on the care delivered to the patient or the safety of healthcare personnel (HCP). These practices may be used temporarily during periods of expected eye protection shortages.
Crisis capacity: strategies that are not commensurate with U.S. standards of care. These measures, or a combination of these measures, may need to be considered during periods of known eye protection shortages.

Reuse-extended usediscard if damaged, soilded, wet
Examples of administrative controls
Reducing the number of patients going to the hospital or outpatient settings
Excluding HCP not essential for patient care from entering their care area
Reducing face-to-face HCP encounters with patients
Excluding visitors to patients with confirmed or suspected COVID-19
Cohorting patients and HCP
Maximizing use of telemedicine

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When does SARS-CoV2 transmission occur?
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18 patients in China with serial PCRs from throat and nose
Highest viral load soon after symptom onset
Similar high viral load in 1 asymptomatic patient
Zou L N Engl J Med 2020; 382:

Pattern of SARS-CoV-2 viral shedding mimics influenza
Zou et al, NEJM 2020; DOI: 10.1056/NEJMc2001737
Peiris et al, Lancet 2003; 361: 1767-72
Tsang et al, J Infect Dis 2015; 212; 1420-28
SARS-CoV-2
SARS
Seasonal Influenza
Slide courtesy of Yoko Furuya

Asymptomatic/presymptomatic transmission occurs and complicates control efforts
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https://wwwnc.cdc.gov/eid/article/26/7/20-1595_article Ferretti L Science 2020; Arons MM NEJM 2020
Epidemiological evidence
Family clusters
Outbreak in long-term care nursing facilities
Virological evidence
High viral load in presymptomatic/asymptomatic period
Modeling evidence
13-50% of infections possibly due to asymptomatic

PCR positivity may persist for weeks, but does not correlate with isolation of live virus
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Sethuraman N. JAMA 2020

How long are patients infectious?
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9 hospitalized patients in Germany
Serial nasal and oral swabs for PCR
No positive viral cultures after day 8 from symptom onset
WlfelR et al. Nature 2020

How long are patients infectious?
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First 12 US COVID-19 patients
Tested serially over time
N=448 total specimens
Nasal, oral, sputum, serum, stool, urine
No positive cultures after day 9
Kujawski SA Nature Med 2020
https://www.cdc.gov/coronavirus/2019-ncov/community/strategy-discontinue...

Epidemiological data suggests transmission occurs early ( 5 days from symptom onset
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Contact tracing of first 100 cases in Taiwan
2761 close contacts
22 secondary cases
All had exposure before day 6 of symptom onset
Attack rate comparable between pre-symptomatic and early symptomatic exposure

Cheng HY et al JAMA Intern Med 2020

CDC, NYS DOH recommend at least 10 days of home isolation after COVID-19
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Phases of pandemic preparedness planning
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https://preventepidemics.org/covid19/

9/10 NYS regions have met all 7 reopening metrics
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https://forward.ny.gov/covid-19-regional-metrics-dashboard

Universal masking is critical strategy to reduce SARS-CoV-2 in healthcare settings
All patients/visitors and staff should wear a face covering or face mask
Exceptions children < 2 years, behavioral, cognitive impairment
Highly effective for containing coronavirus and influenza droplets/aerosols
If moderate-high community transmission, consider eye protection for HCP when SARS-CoV-2 status unknown and/or patient unable to reliably wear mask
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Prather K et al Science 2020
Leung HK et al Nature Med 2020
https://www.cdc.gov/coronavirus/2019-ncov/hcp/infection-control-faq.html
Viral shedding in respiratory droplet/aerosol samples obtained in patient with influenza, coronavirus with and without mask. 0
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Minimize unnecessary exposures
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Symptom screening
Telemedicine
Registration process
Scheduling
Dedicated hours/teams
Limit accompanying visitors
Consider NYC/NYS DOH COVID-19 testing sites
Environmental cleaning disinfection

https://www1.nyc.gov/assets/doh/downloads/pdf/imm/covid-19-infection-con...

https://www.nytimes.com/2020/05/08/health/coronavirus-telemedicine-senio...

Implement physical distancing measures in common areas
Signage
Floor decals/markers
Waiting room chair arrangement
Limit elevator capacity
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Public health strategy for containing re-emergence of COVID-19
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https://preventepidemics.org/covid19/

Prioritized groups for COVID testing in New York state
Any symptomatic patient
>70 years of age, immunocompromise or comorbidities
< 21 years of age who has symptoms consistent with Multisystem Inflammatory Syndrome in Children (MIS-C),
Prior to an elective surgery or procedure, pregnancy;
Close (i.e. within six feet) contacts with known to be positive with COVID-19
Health care worker, first responder, employee of a nursing home, long-term care facility, or other congregate care facility, or other essential employee who directly interacts with the public while working
Essential business employees or any business that has been designated to "reopen" in certain regions of the state (e.g. construction, curbside/in-store pickup retail, wholesale trade);
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NYS DOH 5/31/20 https://coronavirus.health.ny.gov/covid-19-testing

Contact tracing
New COVID cases reported to local health department
Contact tracer identifies patient's resource needs and close contacts
>15 minutes of close contact
Confidential
Minimum 30 per 100,000 persons
~2,500 needed in NYC

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https://coronavirus.health.ny.gov/new-york-state-contact-tracing

COVID-19 vaccine development is advancing at unprecedented speed globally
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Le TT Nature Reviews Drug Discovery 2020 (19)

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Phase 1 trial of recombinant adenovirus virus vaccine expressing SARS-CoV-2 spike glycoprotein
108 participants
3 dose groups
No major adverse events at 28 days
Neutralizing antibodies peaked at 28 days post vaccination (97-100%)
T-cell responses peaked at day 14

Zhu, FC Lancet 2020

Key points
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COVID-19 epidemic has improved across New York but major global challenges remain
Respiratory droplets are major mode of transmission, but better understanding of other potential modalities still needed
Infectivity peaks early in disease course, but asymptomatic and presymptomatic transmission is a major challenge to disease control
Universal masking, physical distancing, hand hygiene, PPE are crucial preventive strategies presently

Acknowledgements
David Calfee
Yoko Furuya
NYP Infection Prevention & Control team
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