The WHO continuously reviews available data on SARS-CoV-2 variants of concern. For this version, the global epidemiological
situation of the COVID-19 pandemic as of 21 January 2022 – at a time when the Omicron VOC had been identified in 171
countries across all six WHO Regions and was rapidly re...placing Delta worldwide – was considered Omicron has a substantial growth advantage, higher secondary attack rates and a higher observed reproduction number than Delta.
There is now significant evidence that immune evasion contributes to the rapid spread of Omicron. Other factors may be a shorter
serial interval (by about 0.8 to 1.2 days compared to Delta) and potential increased intrinsic transmission fitness . There is
growing evidence that with Omicron, there is lower vaccine effectiveness (VE) against infection and symptomatic disease soon after vaccination compared to Delta. There is also evidence of accelerated waning of VE over time of the primary series against infection and symptomatic disease for the studied vaccines. Further studies are required to better understand the drivers of transmission and declining incidence in various settings. These factors include the intrinsic transmission fitness properties of the virus, degree of immune evasion, vaccination coverage and level of vaccine-derived and post-infection immunity, levels of social mixing and degree of application of public health and social measures (PHSM).
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22 April 2022, This document provides updated interim recommendations on the use of masks by health workers providing care to patients with suspected or confirmed COVID-19. This update is prompted by new evidence around mask use and COVID-19 transmission, as well as the emergence of variants of conc...ern including Omicron. Masks continue to be a critical tool to prevent the spread of COVID-19. These interim guidelines supersede the recommendations provided in the WHO recommendations on mask use by health workers, in light of the Omicron variant of concern published on 22 December 2022.
WHO continually evaluates the emerging evidence and will review these interim recommendations within two months and issue new guidance as needed.
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MMWR. Recommendations and Reports:
December 16, 2005 / 54(RR15);49-55
Annex. This document is an update of a guidance published on 12 July 2021, after the review of new scientific evidence on transmission of SARS-CoV-2 variants of concern (VOC). It contains updated recommendations on the use of masks and respirators for health workers providing care to suspected or c...onfirmed COVID-19.
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African Journal of Emergency Medicine
Volume 11, Issue 1, March 2021, Pages 165-170
2018
Vol.5 No.2:73
DOI: 10.21767/2254-9137.100092
Health Systems and Policy Research ISSN 2254-9137
The Journal of Infectious Diseases, jiy435, https://doi.org/10.1093/infdis/jiy435.
Many outbreaks reported high proportions of infected HWs. Similar HW infection rates and exposure risk factors in both past and recent EVD and MVD outbreaks emphasize the need to improve the implementation of approp...riate infection control measures consistently across all healthcare settings.
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These WHO guidelines which were updated in 2018, are valid for any country and suitable to local adaptations, and take account of the strength of available scientific evidence, the cost and resource implications, and patient values and preferences.
The 2018 edition of the guidelines includes the re...vision of the recommendation regarding the use of 80% fraction of inspired oxygen (high FiO2) in surgical patients under general anaesthesia with tracheal intubation and the update of the section on implementation. Between 2017 and 2018, WHO re-assessed the evidence on the use of high FiO2 by updating the systematic review related to the effectiveness of this intervention to reduce SSI and commissioning an independent systematic review on adverse events potentially associated with it. Based on the updated evidence, the GDG decided to revise the strength of the recommendation from strong to conditional.
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The International Journal of Tuberculosis and Lung Disease 21(5) DOI: 10.5588/ijtld.16.0518
BMC Public Health (2016) 16:766
DOI 10.1186/s12889-016-3455-5
Recommended actions and international and national level
Recommended actions at international and national levels