Update with Consideration of Omicron - Interim COVID-19 Infection Prevention and Control in the health care setting when COVID-19 is suspected or ...
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Update with Consideration of Omicron – Interim COVID-19 Infection
Prevention and Control in the health care setting when COVID-19 is suspected
or confirmed– December 23, 2021
With the identification of the new COVID-19 variant of concern-Omicron, this update has been developed to
emphasize and provide additional recommendations to the COVID-19 infection prevention and control measures
outlined in the COVID-19 infection prevention and control guidance documents. These recommendations are for
all health care settings (acute care, long term care, home care and ambulatory/outpatient care)
Background
On November 26, 2021, WHO designated the variant B.1.1.529 (Omicron variant) a variant of concern (VOC).
Subsequently, on November 28, 2021, the Canadian SARS-CoV-2 Variant Surveillance Group designated it as a
Variant of Concern for Canada. Omicron is a highly divergent variant with a high number of mutations, many of
these found on the spike protein. The Omicron variant has been shown to be much more transmissible than the
Delta variant and has some vaccine immune escape. It is unknown if the disease severity will be different than
other circulating variants.
Factors affecting the risk of acquisition of healthcare associated SARS-CoV-2 infection include:
- higher level of community transmission
- poor ventilation within the facility
- healthcare workers’ (HCW) proximity to the patient
- multi-bed rooms
- longer durations of exposure to the patient
- inappropriate use of personal protective equipment (PPE), including masks and eye protection
- patient behaviours (e.g., coughing, yelling, ability to wear a mask)
- timing within disease course
- patients with higher viral loads
Evidence on the transmission of SARS-CoV-2 virus has advanced rapidly and continues to emerge. Respiratory
fluids continue to be the primary mode of transmission for COVID-19 via large respiratory droplets and small
aerosol particles. Infections occur when respiratory mucosa (mouth, nose, eyes) are exposed to these
respiratory droplets and aerosol particles. Individuals can release SARS-CoV-2 virus particles during any
exhalations (e.g., talking, breathing, singing, exercising, coughing, sneezing). These aerosol particles can remain
suspended in the air, and be inhaled into the respiratory tract of another person. With the arrival of the very
transmissible Omicron variant, that appears to have some degree of immune escape, this new information is
considered in these interim recommendations for infection prevention and control in health care settings.
Recommendations
Recommendations for health care settings include the following:
Continue to adhere to, reinforce, evaluate and monitor the full range of existing COVID-19 infection prevention
and control measures and guidance
Continue to implement and re-evaluate the hierarchy of controls within the healthcare environment including:
o organizational controls, including engineering and administrative controls
o all HCWs should be vaccinated with booster vaccines when 6 months has passed since their
second dose
o given the occurrence of breakthrough infections with SARS-CoV-2 in people who have received
a partial or full vaccination course, PPE use should not be differentiated based on patient or
health care provider COVID-19 vaccination status
o processes and written procedures to manage HCW exposures to COVID-19 and illness
o environmental cleaning and disinfection
o active screening and notification prompt identification of all individuals (including inpatients) with signs or symptoms of
COVID-19 infection should occur via active screening
o physical distancing
Direct care of patients with suspected or confirmed COVID-19:
well fitted respirator
eye protection (e.g., goggles or face shield)
gowns
gloves
Recommended PPE for all patient encounters should be based on a point of care risk assessment (PCRA),
which should consider:
community epidemiology of COVID-19
ventilation assessed by the organization as adequate
crowding and occupancy of spaces
patient not yet clinically evaluated (e.g., Emergency Areas)
likelihood of exposure to SARS-CoV-2 and other pathogens based on:
specific interaction
specific task
specific patient
specific environment, and
available conditions
Aerosol exposure – Historically, certain procedures were thought to pose a higher risk for health care workers on
the basis of case–control studies, mainly from SARS-CoV-1, that reported associations between selected
procedures and health care worker infections. These have been called Aerosol Generating Medical Procedures
(AGMPs). As scientific inquiry quantifies the aerosols produced by such procedures, it appears that they do not
cause any more aerosols than coughing, singing or talking loudly. Aerosol production can also vary by individual.
As these concepts are studied, a better understanding may lead to a change in infection control guidance. Until
then it is prudent to continue to use fit tested N95 respirators, eye protection, gowns and gloves for all AGMPs.
Health care workers can choose to wear a respirator at any time taking into account such factors as the
community incidence of SARS-CoV-2, patient’s ability to tolerate a mask, patient behaviours such as shouting or
heavy breathing, requirement of extensive or prolonged close proximity, and other factors.
Masking for the full duration of shifts or visits
Given ongoing community spread of COVID-19 within Canada and evidence that transmission occurs from those
who have few or no symptoms, masking for the full duration of shifts or visits has become normal practice during
the COVID-19 pandemic. The rationale for full-shift or visit masking of all staff and visitors is to reduce the risk of
transmitting COVID-19 from staff or visitors to others, at a time when no symptoms of illness are recognized, but
the virus can be transmitted. The mask also protects the wearer. Depending on community transmission rates,
the mask chosen can be a medical mask or a respirator. There is increasing evidence that the fit of the mask is
the most important feature. Visitors should wear well-fitting medical masks or KN95 respirators (recognizing that
there are many counterfeit KN95 respirators that may be difficult to verify at point of entry).
Employers must ensure that:
Organizational risk assessments are completed and repeated as needed to determine potential risks for
contamination and transmission of COVID-19 to HCWs, other staff, patients and visitors in any healthcare
setting
COVID-19 vaccines are strongly recommended for HCW and other staff who do not have contraindications.
HCW with direct patient care should be vaccinated. Boosters should be given to all HCW whose second
dose was received 6 months prior
Heating, ventilation and air condition systems are properly installed and regularly inspected and
maintained. Ventilation/air exchanges should be maximized to reduce the risk of transmission in closed
spaces. The use of portable HEPA filters should be considered with the advice of professional experts in this
field Waste, soiled linen and the care environment are managed and adequately cleaned and disinfected according
to facility environmental cleaning policies and procedures
HCW IPC education and training, testing and monitoring for compliance are in place, tracked, recorded, and
kept up-to-date
Processes for teaching, monitoring and evaluating IPC processes and outcomes are in place
Adequate triage and control of facility access points are in place
Active screening activities are in place ensuring:
o a limited number of access points designated for active screening of all HCWs and others
working in the facility
o a limited number of entry points for active screening of patients and visitors
o controls are in place to limit traffic, and to ensure physical distancing and that medical masks are
worn by staff, visitors, and patients (where tolerated) on entry to the facility
o screeners are protected with transparent barriers that allow for communication between
themselves and patients or others who present at screening
All HCWs and other staff (e.g., contractors) who have signs or symptoms of COVID-19, or recent unprotected
contact (as defined by facility, local, and jurisdictional public health or IPC guidance) with a person who is
suspected or confirmed to have COVID-19, or who have been directed to self-isolate according to local public
health directives, do not enter or return to the healthcare setting until they have been cleared to do so
according to local and jurisdictional public health guidance and facility IPC policies
Processes are in place to manage HCW exposures to COVID-19 and HCW illness
There is a policy of medical masks to be worn by all patients when they are within the facility but outside of
their room, or when they are in a shared room with other individuals (e.g., when staff enter their single-bed
room and in multi-bed rooms), while awake and where tolerated should be strongly considered
o Masks should not be used for patients who have difficulty breathing or who are unable to remove
the mask on their own (e.g., due to decreased level of consciousness, physical ability, young
age, mental illness, or cognitive impairment)
All visitors wear well-fitting medical masks or KN95 respirators on entry into the healthcare facility
The number of visitors be minimized to only those who are essential (e.g., immediate family members or
parent, guardian, or primary caregiver), and their movement limited in the facility by visiting the patient
directly and leaving the facility directly after their visit
Visitors are limited, controlled and managed
Information is provided to staff, visitors, and patients who are asked to wear a respirator or mask about the
importance of performing hand hygiene prior to putting on, and after removing or touching their mask, to
reduce risk of self-contamination
o They should also be informed about the steps for proper hand hygiene, and that wearing a
respirator or mask does not lessen the need to adhere to other measures to reduce COVID-19
transmission, such as physical distancing
o Communication materials for visitors should consider the needs of diverse populations such as
those with disabilities and those who’s first language is neither English nor French
Routine Practices, including hand hygiene, are in place for the care of all patients
Every HCW has access to a respirator, so that they can put it on quickly if the need is identified during the
PCRA. No HCW should be denied a respirator at any time
For all other COVID-19 infection prevention and control guidance measures please see: COVID-19 infection
prevention and control guidance documents by healthcare sector.
References
1. Adenaiye OO, Lai J, de Mesquita PJB, et al; University of Maryland StopCOVID Research Group. Infectious
SARS-CoV-2 in exhaled aerosols and efficacy of masks during early mild infection. Clin Infect Dis. 2021. [PMID:
34519774] doi:10.1093/cid/ciab797
2. Alsved M, Matamis A, Bohlin R, et al. Exhaled respiratory particles during singing and talking. Aerosol Science
and Technology. 2020;54(11):1245-1248. doi:10.1080/02786826.2020.18125023. Asadi S, Wexler AS, Cappa CD, Barreda S, Bouvier NM, Ristenpart WD. Aerosol emission and superemission
during human speech increase with voice loudness. Sci Rep. Feb 20 2019;9(1):2348. doi:10.1038/s41598-019-
38808-z
4. Asadi S, Wexler AS, Cappa CD, Barreda S, Bouvier NM, Ristenpart WD. Effect of voicing and articulation manner
on aerosol particle emission during human speech. PLoS One. 2020;15(1):e0227699.
doi:10.1371/journal.pone.0227699
5. Bourouiba L. Turbulent gas clouds and respiratory pathogen emissions: potential implications for reducing
transmission of COVID-19. JAMA.2020;323:1837-1838. [PMID: 32215590] doi:10.1001/jama.2020.4756
6. Brooks JT, Beezhold DH, Noti JD, et al. Maximizing fit for cloth and medical procedure masks to improve
performance and reduce SARS-CoV-2 transmission and exposure, 2021. MMWR Morb Mortal Wkly Rep.
2021;70:254-257. [PMID: 33600386] doi:10.15585 /mmwr.mm7007e1
7. Brown J, Gregson FKA, Shrimpton A, et al. A quantitative evaluation of aerosol generation during tracheal
intubation and extubation. Anaesthesia. 2021;76:174-181. [PMID: 33022093] doi:10.1111/anae
.15292
8. Buonanno G, Stabile L, Morawska L. Estimation of airborne viral emission: Quanta emission rate of SARS-CoV-2
for infection risk assessment. Environment international. May 11 2020;141:105794.
9. Chan P-C, Fang C-T. The role of ventilation in tuberculosis control. J Formos Med Assoc 2021;120(6):1293-1295
10. Chan VW , Ng HH , Rahman L , et al. Transmission of severe acute respiratory syndrome coronavirus 1 and
severe acute respiratory syndrome coronavirus 2 during aerosol-generating procedures in critical care: a
systematic review and meta-analysis of observational studies. Crit Care Med. 2021;49:1159-1168.
[PMID: 33749225] doi:10.1097/CCM.0000000000004965
11. Chen W, Zhang N, Wei J, et al. Short-range airborne route dominates exposure of respiratory infection during
close contact. Build Environ. 2020;176:106859. doi:10.1016/j.buildenv.2020.106859
12. Chen WQ, Ling WH, Lu CY, Hao YT, Lin ZN, et al. Which preventive measures might protect health care workers
from SARS? BMC Public Health 9:81. 2009;1
13. Cheng VC, Fung KS, Siu GK, et al. Nosocomial outbreak of coronavirus disease 2019 by possible airborne
transmission leading to a superspreading event. Clin Infect Dis. 2021;73:e1356-e1364. [PMID: 33851214]
doi:10.1093/cid/ciab313
14. Coleman KK, Tay DJW, Sen Tan K, et al. Viral load of SARS-CoV-2 in respiratory aerosols emitted by COVID-19
patients while breathing, talking, and singing. Clin Infect Dis. 2021. [PMID: 34358292]doi:10.1093/cid/ciab691
15. Crawford C, Vanoli E, Decorde B, et al. Modeling of aerosol transmission of airborne pathogens in ICU rooms of
COVID-19 patients with acute respiratory failure. Sci Rep 2021;11:11778
16. Doung-Ngern P, Suphanchaimat R, Panjangampatthana A, et al. Case-control study of use of personal protective
measures and risk for SARS-CoV 2 infection, Thailand. Emerg Infect Dis. 2020;26:2607-2616. [PMID: 32931726]
doi:10.3201/eid2611.203003
17. Echternach M, Gantner S, Peters G, et al. Impulse Dispersion of Aerosols during Singing and Speaking: A
Potential COVID-19 Transmission Pathway. Am J Respir Crit Care Med. Dec 1 2020;202(11):1584-1587.
doi:10.1164/rccm.202009-3438LE
18. Edwards DA, Ausiello D, Salzman J, et al. Exhaled aerosol increases with COVID-19 infection, age, and
obesity. Proc Natl Acad Sci U S A. Feb 23 2021;118(8)doi:10.1073/pnas.2021830118
19. Enhancing Readiness for Omicron (B.1.1.529): Technical Brief and Priority Actions for Member States - 28
November 2021. UK Health Security Agency. SARS-CoV-2 variants of concern and variants under investigation
in England: technical briefing 29 [Internet]. London: Crown Copyright; 2021 [cited 2021 Dec 10].
20. European Centre for Disease Prevention and Control. Threat Assessment Brief: Implications of the emergence
and spread of the SARS-CoV-2 B.1.1. 529 variant of concern (Omicron) for the EU/EEA.
https://www.ecdc.europa.eu/en/publications-data/threat-assessment-brief-emergence-sars-cov-2- variant-
b.1.1.529 4
21. Fennelly KP. Particle sizes of infectious aerosols: Implications for infection control. Lancet Respir Med
2020;8(9):914-924
22. Goldberg L, Levinsky Y, Marcus N, et al. SARS-CoV-2 infection among health care workers despite the use of
surgical masks and physical distancing—the role of airborne transmission. Open Forum Infect Dis.
2021;8:ofab036. [PMID: 33732749] doi:10.1093/ofid /ofab03623. Gaeckle NT, Lee J, Park Y, et al. Aerosol generation from the respiratory tract with various modes of oxygen
delivery. Am J Respir Crit Care Med. 2020;202:1115-1124. [PMID: 32822208] doi:10
.1164/rccm.202006-2309OC
24. Greenhalgh T, Jimenez JL, Prather KA, et al. Ten scientific reasons in support of airborne transmission of SARS-
CoV-2. Lancet. 2021;397:1603- 1605. [PMID: 33865497] doi:10.1016/S0140-6736(21)00869-2
25. Grijalva CG, Rolfes MA, Zhu Y, et al. Transmission of SARSCOV-2 infections in households - Tennessee and
Wisconsin, April-September 2020. MMWR Morb Mortal Wkly Rep. 2020;69:1631-1634. [PMID: 33151916]
doi:10.15585/mmwr.mm6944e1
26. Hamner L, Dubbel P, Capron I, et al. High SARS-CoV-2 attack rate following exposure at a choir practice - Skagit
County, Washington, March 2020. MMWR Morb Mortal Wkly Rep. 2020;69:606-610. [PMID: 32407303]
doi:10.15585/mmwr.mm6919e6
27. Hu M, Lin H, Wang J, et al. Risk of coronavirus disease 2019 transmission in train passengers: an
epidemiological and modeling study. Clin Infect Dis. 2021;72:604-610. [PMID: 32726405] doi:10.1093/cid
/ciaa1057
28. Jacob JT, Baker JM, Fridkin SK, et al. Risk factors associated with SARS-CoV-2 seropositivity among US health
care personnel. JAMA Netw Open. 2021;4:e211283. [PMID: 33688967] doi:10.1001/jamanetworkopen.2021.1283
29. Shah ASV, Wood R, Gribben C, et al. Risk of hospital admission with coronavirus disease 2019 in healthcare
workers and their households: nationwide linkage cohort study. BMJ. 2020;371: m3582. [PMID: 33115726]
doi:10.1136/bmj.m3582
30. Johansson MA, Quandelacy TM, Kada S, et al. SARS-CoV-2 transmission from people without COVID-19
symptoms. JAMA Netw Open. 2021;4:e2035057. [PMID: 33410879] doi:10.1001
/jamanetworkopen.2020.35057
31. Karan A, Klompas M, Tucker R, et al; CDC Prevention Epicenters Program. The risk of SARS-CoV-2
transmission from patients with undiagnosed Covid-19 to roommates in a large academic medical center. Clin
Infect Dis. 2021. [PMID: 34145449] doi:10.1093/cid/ciab564
32. Kawasuji H, Takegoshi Y, Kaneda M, et al. Transmissibility of COVID-19 depends on the viral load around onset
in adult and symptomatic patients. PLoS One. 2020;15:e0243597. [PMID: 33296437]
doi:10.1371/journal.pone.0243597
33. Klompas M, Baker M, Rhee C. What is an aerosol-generating procedure. JAMA Surg. 2021;156:113-114. [PMID:
33320188] doi:10.1001/jamasurg.2020.6643
34. Klompas M, Baker MA, Rhee C, et al. A SARS-CoV-2 cluster in an acute care hospital. Ann Intern Med.
2021;174:794-802. [PMID: 33556277] doi:10.7326/M20-7567
35. Klompas M, Baker MA, Griesbach D, et al. Transmission of SARS-CoV-2 from asymptomatic and
presymptomatic individuals in healthcare settings despite medical masks and eye protection. Clin Infect Dis.
2021. [PMID: 33704451] doi:10.1093/cid/ciab218
36. Klompas M, Ye S, Vaidya V, et al. Association between airborne infection isolation room utilization rates and
healthcare worker COVID-19 infections in two academic hospitals. Clin Infect Dis. 2021. [PMID: 34599821]
doi:10.1093/cid/ciab849
37. Lam-Hine T, McCurdy SA, Santora L, et al. Outbreak associated with SARS-CoV-2 B.1.617.2 (Delta) variant in
an elementary school -Marin County, California, May-June 2021. MMWR Morb Mortal Wkly Rep. 2021;70:1214-
1219. [PMID: 34473683] doi:10.15585/mmwr.mm7035e2
38. Lee LYW, Rozmanowski S, Pang M, et al. SARS-CoV-2 infectivity by viral load, S gene variants and
demographic factors and the utility of lateral flow devices to prevent transmission. Clin Infect Dis.2021. [PMID:
33972994] doi:10.1093/cid/ciab421
39. Leung NHL. Transmissibility and transmission of respiratory viruses. Nat Rev Microbiol 2021;19:528-545.
40. Leung NHL, Xu C, Ip DK, et al. Review article: the fraction of influenza virus infections that are asymptomatic: a
systematic review and meta-analysis. Epidemiology. 2015;26:862-72. [PMID: 26133025]
doi:10.1097/EDE.0000000000000340
41. Leung NHL, Chu DKW, Shiu EYC, et al. Respiratory virus shedding in exhaled breath and efficacy of face masks.
Nat Med. 2020;26:676-680. [PMID: 32371934] doi:10.1038/s41591-020-0843-2
42. Li Y, Qian H, Hang J, et al. Probable airborne transmission of SARSCoV-2 in a poorly ventilated restaurant. Build
Environ. 2021;196:107788. [PMID: 33746341] doi:10.1016/j.buildenv.2021.10778843. Lindsley WG, Derk RC, Coyle JP, et al. Efficacy of portable air cleaners and masking for reducing indoor
exposure to simulated exhaled SARSCoV-2 aerosols - United States, 2021. MMWR Morb Mortal Wkly
Rep.2021;70:972-976. [PMID: 34237047] doi:10.15585/mmwr.mm7027e1
44. Liu W, Tang F, Fang L-Q, De Vlas SJ, Ma H-J, et al. Risk factors for SARS infection among hospital healthcare
workers in Beijing: A case control study. Trop Med Int Health. 2009;14:52–59
45. Loeb M, McGeer A, Henry B, Ofner M, Rose D, et al. SARS among critical care nurses, Toronto. Emerg Infect
Dis. 2004;10:251–255
46. Lordon RG, Roberts RM. Droplet expulsion from the respiratory tract. Am Rev Respir Dis 1967;95(3):435-442.
47. Lu J, Gu J, Li K, et al. COVID-19 outbreak associated with air conditioning in restaurant, Guangzhou, China,
2020. Emerg Infect Dis. 2020;26:1628-1631. [PMID: 32240078] doi:10.3201/eid2607.200764
48. Ma HJ, Wang HW, Fang LQ, Jiang JF, Wei MT, et al. A case-control study on the risk factors of severe acute
respiratory syndromes among health care workers. Chung-Hua Liu Hsing Ping Hsueh Tsa Chih Chinese Journal
of Epidemiology. 2004;25:741–744
49. Marks M, Millat-Martinez P, Ouchi D, et al. Transmission of COVID-19 in 282 clusters in Catalonia, Spain: a
cohort study. Lancet Infect Dis. 2021;21:629-636. [PMID: 33545090] doi:10.1016/S1473-3099(20)30985-3
50. McEllistrem MC, Clancy CJ, Buehrle DJ, et al. SARS-CoV-2 is associated with high viral loads in asymptomatic
and recently symptomatic healthcare workers. PLoS One. 2021;16:e0248347. [PMID: 33735264]
doi:10.1371/journal.pone.0248347
51. Miller SL, Nazaroff WW, Jimenez JL, et al. Transmission of SARS-CoV-2 by inhalation of respiratory aerosol in
the Skagit Valley Chorale superspreading event. Indoor Air. 2021;31:314-323. [PMID: 32979298]
doi:10.1111/ina.12751
52. Mo Y, Eyre DW, Lumley SF, et al. Transmission dynamics of SARS-CoV-2 in the hospital setting. medRxiv.
Preprint posted online 1 May 2021. doi:10.1101/2021.04.28.21256245
53. O’Kelly E, Arora A, Pirog S, Ward J, Clarkson PJ (2021) Comparing the fit of N95, KN95, surgical, and cloth face
masks and assessing the accuracy of fit checking. PLoS ONE 16(1): e0245688
54. Morawska L., Johnson GR, Ristovski ZD, et al. Size distribution and sites of origin of droplets expelled from the
human respiratory tract during expiratory activities. Aerosol Sci. 2009;40(3):256-269
55. Nardell EA, Nathavitharana RR. Airborne spread of SARS-CoV-2 and a potential role for air disinfection. JAMA.
2020;324:141-142. [PMID: 32478797] doi:10.1001/jama.2020.7603
56. Oksanen LAH, Sanmark E, Oksanen SA, et al. Sources of healthcare workers' COVID-19 infections and related
safety guidelines. Int J Occup Med Environ Health. 2021;34:239-249. [PMID: 33847307]
doi:10.13075/ijomeh.1896.01741
57. O’Neil CA, Li J, Leavey A, et al; Centers for Disease Control and Prevention Epicenters Program.
Characterization of aerosols generated during patient care activities. Clin Infect Dis. 2017;65:1335-
1341. [PMID: 29017249] doi:10.1093/cid/cix535
58. Papineni RS, Rosenthal FS. The size distribution of droplets in the exhaled breath of healthy human subjects. J
Aerosol Med. Summer 1997;10(2):105-16. doi:10.1089/jam.1997.10.105
59. Pei LY, Gao ZC, Yang Z, Wei DG, Wang SX, et al. Investigation of the influencing factors on severe acute
respiratory syndrome among health care workers. Beijing da xue xue bao Yi xue ban - Journal of Peking
University Health sciences. 2006;38:271–275
60. Randall K, Ewing ET, Marr LC, et al. How did we get here: what are droplets and aerosols and how far do they
go? A historical perspective on the transmission of respiratory infectious diseases.
Interface Focus. 2021;11:20210049. doi:10.1098/rsfs.2021.0049
61. Sajgalik P, Garzona-Navas A, Csecs I, et al. Characterization of aerosol generation during various intensities of
exercise. Chest. 2021;160:1377-1387. [PMID: 33957100] doi:10.1016/j.chest.2021.04.041
62. Sickbert-Bennett EE, Samet JM, Clapp PW, et al. Filtration efficiency of hospital face mask alternatives available
for use during the COVID-19 pandemic. JAMA Intern Med. 2020;180:1607-1612. [PMID: 32780113]
doi:10.1001/jamainternmed.2020.4221
63. Schijven J, Vermeulen LC, Swart A, Meijer A, Duizer E, de Roda Husman AM. Quantitative microbial risk
assessment for airborne transmission of SARS-CoV-2 via breathing, speaking, singing, coughing, and sneezing.
Environ Health Perspect 2021;129(4):47002.64. Sheward D, Kim C, Pankow A, et al. Preliminary report – Early release, subject to modification: Quantification of
the neutralization resistance of the Omicron Variant of Concern.
https://drive.google.com/file/d/1CuxmNYj5cpIuxWXhjjVmuDqntxXwlfXQ/view [preprint]
65. Stadnytskyi V, Bax CE, Bax A, Anfinrud P. The airborne lifetime of small speech droplets and their potential
importance in SARS-CoV-2 transmission. Proc Natl Acad Sci U S A. Jun 2 2020;117(22):11875-11877.
doi:10.1073/pnas.2006874117
66. Stadnytskyi V, Anfinrud P, Bax A. Breathing, speaking, coughing or sneezing: What drives transmission of SARS-
CoV-2? J Intern Med 2021;(8).
67. Stockwell RE, Ballard EL, O’Rourke P, Knibbs LD, Morawska L, Bell SC. Indoor hospital air and the impact of
ventilation on bioaerosols: A systematic review. J Hosp Infect 2019;103(2):175-184
68. Tang JW, Marr LC, Li Y, et al. Covid-19 has redefined airborne transmission [Editorial]. BMJ. 2021;373:n913.
[PMID: 33853842]doi:10.1136/bmj.n91
69. Teleman MD, Boudville IC, Heng BH, Zhu D, Leo YS. Factors associated with transmission of severe acute
respiratory syndrome among health-care workers in Singapore. Epidemiology & Infection. 2004;132:797–803
70. Tran K , Cimon K , Severn M , et al. Aerosol generating procedures and risk of transmission of acute respiratory
infections to healthcare workers: a systematic review. PLoS One. 2012;7:e35797. [PMID: 22563403]
doi:10.1371/journal.pone.0035797
71. Trannel AM, Kobayashi T, Dains A, et al. Coronavirus disease 2019 (COVID-19) incidence after exposures in
shared patient rooms in a tertiary-care center in Iowa, July 2020-May 2021. Infect Control Hosp Epidemiol.
2021:1-4. [PMID: 34250882] doi:10.1017/ice.2021.313
72. Wilhem A, Widera M, Grikscheit K, et al. Reduced Neutralization of SARS-CoV-2 Omicron Variant Vaccine Sera
and monoclonal antibodies. medRxiv 2021.12.07.21267432
73. Wilson NM, Marks GB, Eckhardt A, et al. The effect of respiratory activity, non-invasive respiratory support and
facemasks on aerosol generation and its relevance to COVID-19. Anaesthesia. 2021;76:1465-1474. [PMID:
33784793] doi:10.1111/anae.15475 -1474. [PMID: 33784793] doi:10.1111/anae.15475You can also read
