SARS-CoV-2 routes of transmission and recommendations for preventing acquisition: joint British Infection Association (BIA), Healthcare Infection Society (HIS), Infection Prevention Society (IPS) and Royal College of Pathologists (RCPath) guidance

Abstract

The pandemic of the coronavirus disease 2019 (COVID-19), caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged amid uncertainty about the dynamics of transmission and the possible management options for COVID-19 patients. This resulted in confusion for healthcare workers (HCWs) and hospital managers who often received conflicting advice on how to organise care and manage infected individuals without increasing the risk of transmission to HCWs and other patients. Advice for the public has also been confusing and apparently sometimes contradictory, which sometimes resulted in overuse of Personal Protective Equipment (PPE) in the general population as well as in healthcare workers. As evidence from the first wave has emerged, we are now in a position to summarise it and provide guidance on how to prevent SARS-CoV-2 transmission whilst preserving essential resources. This article is the first of two guidance documents produced jointly by the Healthcare Infection Society, British Infection Association, Infection Prevention Society and Royal College of Pathologists. This guidance article describes routes of SARS-CoV-2 transmission, which will allow the public and healthcare professionals to understand how SARS-CoV-2 transmission occurs. By determining how likely transmission can occur via a given route, we can extrapolate the evidence for infection prevention and control (IPC) and apply this knowledge to optimise protection from SARS-CoV-2 infection. At the time of writing (April 2021), new variants of SARS-CoV-2 emerged, raising concerns whether the virus could make current vaccines ineffective. The evidence strongly suggests that these variants have a transmission potential higher than the original virus thus, strict adherence to IPC measures is still required in breaking the chain of SARS-CoV-2 transmission. Further review may be required as more evidence about these variants becomes available. On review of the evidence, the COVID-19 Rapid Guidance Working Party considers the different transmission routes as follows:droplet transmission: probabletransmission via fomites: possibleairborne transmission: possible (in some circumstances, e.g., aerosol generating procedures (AGPs)transmission via ocular surface: possiblevertical transmission: unlikelytransmission from different body fluids (other than respiratory secretions and saliva): unlikelytransmission from blood transfusion and transplantation organs: unlikely The Working Party concludes that transmission most often occurs following close contact, especially where PPE is not worn, as reflected in high transmission rates between family members, friends, and co-workers. At the moment it is not possible to determine the distance or the duration over which transmission can occur, although these vary depending on circumstances (e.g. the shorter the distance, the shorter the duration of contact will be required, but also on environmental and other factors). Transmission from COVID-19 patients to HCWs in hospitals is low, except in a small number of cases where HCWs cared for undiagnosed COVID-19 patients and did not use appropriate PPE. Even in these cases, transmission usually occurs during AGPs. Transmission in care homes appears to be very high and anecdotal evidence suggests that there were difficulties in obtaining appropriate PPE and observing social distancing during the pandemic. The published literature is not comprehensive enough to make recommendations for this setting. However, considering there is no IPC guidance specific for care homes, we suggest that staff in these institutions follow the recommendations for persons working in health and care settings listed below and that they explore aspects specific to their local institutions to address the barriers which prevent them in doing so, e.g. inability to maintain social distancing. The rationale for the above conclusions and the following recommendations is provided in Section Review of evidence. General recommendations which apply to all settings, including social settings: GR1: Adhere to regulations currently imposed by your government. Specific guidance may be available from your government. GR2: Maintain the recommended minimum distance, as advised by your government, at all times. GR3: Use a face covering in enclosed spaces to protect yourself and others. GR4: Reduce the time of contact with anyone outside your household to a minimum. GR5: To avoid transmission from fomites, decontaminate your hands frequently using soap and water, and when this is not possible, use alcohol-based hand rub.Good practice point: Follow World Health Organization advice on how to handwash (https://www.who.int/gpsc/5may/How_To_HandWash_Poster.pdf) and how to handrub (https://www.who.int/gpsc/5may/How_To_HandRub_Poster.pdf) GR6: Avoid touching your face and eyes with your hands as transmission via ocular surface is possible. GR7: Evidence suggests that a high proportion of transmissions occur as a result of close contact between family members, friends, and co-workers. Adhere to the above recommendations when in contact with anyone outside your household or support network. GR8: Available evidence suggests that transmission without close contact or outside is unlikely. Continue maintaining your locally determined distance (which is 2m within the UK) and using face covering in indoor settings. There is no evidence which suggests that respirator masks (e.g. N95, FFP2/3) offer additional protection outside the healthcare settings.Good practice point: To protect yourself and others, follow WHO advice and avoid 3Cs: Closed spaces, Crowds, Close contact. Specific recommendations for persons working in health and care settings: HR1: You must adhere to regulations imposed by your trust/employer. HR2: Where there is ongoing transmission, for contact with patients and other healthcare staff, use a fluid-resistant face mask, and adhere to general recommendations listed above. HR3: For care of patients suspected or confirmed to have COVID-19, in addition to the above, use fluid resistant surgical face mask and adhere to contact and droplet precautions. No other precautions are necessary. HR4: Risk of SARS-CoV-2 transmission from body fluids (faeces, urine, ocular excretions, and sexual body fluids) is unlikely, use contact precautions and appropriate PPE (including fluid resistant surgical face mask type IIR) and do not use additional precautions (e.g., filtering respiration mask) unless carrying out AGPs. Your employer may make a decision to provide respirator masks for procedures other than AGPs, based on local circumstances. HR5: Whilst blood and body fluids are not a likely source of SARS-CoV-2 infection, there remains a risk of infection with other pathogens to HCWs and via them to other patients. Use PPE (gloves, plastic aprons, eye protection) as appropriate when there is a risk of exposure to blood, body fluids or any items contaminated with these products and clean your hands immediately after glove removal. HR6: Literature suggests that most SARS-CoV-2 transmissions from patients to HCWs occurred when HCW did not use protection during AGPs on patients not suspected of having COVID-19. Consider using filtering respiration mask (FFP3) designed for filtering fine airborne particles for any AGPs regardless of a patient's COVID-19 status when local assessment suggests risk of SARS-CoV-2 circulating in the community or local setting. HR7: Vertical transmission is unlikely. Studies have reported avoiding caesarean delivery where possible and mothers being advised to use a surgical mask. Summary of recommendations is provided in Table I.Table ISummary of recommendations for persons working in healthcare settingsCasual contact – no patient careCare for non-COVID-19 patientsCare for suspected or confirmed COVID-19 patientsPrecautionsSocial distancingStandard precautions: hand hygiene, respiratory hygiene, sharps safety, environmental & equipment safety, safe injections, PPE, occupational safety, social distancing∗Note: social distancing is now a part of standard precautions.Standard precautions, contact precautions & droplet precautionsPatient managementPatient to wear face coveringPatient to wear face covering (as per local policies)Patient placed in isolation/single room or as far away from others as possible (and at least 2m within the UK)Patient to wear fluid resistant surgical face mask when in contact with othersPPE if no contact with body fluidsFace protectionFace coveringFluid resistant surgical face maskFluid resistant surgical face mask typeGlovesNoneNoneSingle use, double gloving not necessaryClothes/body protectionBare below elbowBare below elbowBare below elbow, apron tied at neck and waistEye protectionNoneNoneFace shieldHead protectionNoneNoneNoneFoot/shoe protectionNoneNoneNonePPE if in contact with body fluidsFace protectionn/aFluid resistant surgical face maskFluid resistant surgical face maskGlovesSingle use, double gloving not necessarySingle use, double gloving not necessaryClothes/body protectionBare below elbow, apron (if risk of contamination) tied at neck and waistBare below elbow, apron (if risk of contamination) tied at neck and waistEye protectionFace shield (if risk of splashes)Face shield (if risk of splashes)Head protectionNoneNoneFoot/shoe protectionNoneNonePPE if AGPs performedFace protectionn/aFiltering respiration mask FFP3Filtering respiration mask FFP3GlovesSingle use, covering the cuffs of the gownSingle use, covering the cuffs of the gownClothes/body protectionLong sleeved gownLong sleeved gownEye protectionGogglesGogglesHead protectionNoneNoneFoot/shoe protectionNoneNone∗ Note: social distancing is now a part of standard precautions. Open table in a new tab Recommendations for managers in health and care settings: MR1: Adhere to current national guidelines for IPC, including those specific to COVID-19 as well as general ones for preventing infectious diseases. MR2: Consider exploring potential factors for SARS-CoV-2 transmission specific to your setting, e.g., inability to maintain social distancing and managing apparently asymptomatic cases. The COVID-19 pandemic has had far reaching implications for health, economics and society. One of the many areas affected has been the ability of healthcare professionals to stop the spread of the infection in health and care settings both in hospital and in the community such as a dental surgery. With research being published since the emergence of the outbreak we now have a much better understanding of how to help prevent the spread of the infection. This document was co-produced by a multiprofessional group that includes clinicians, nurses, academics, and a member of the public. It provides the current evidence with recommendations to help frontline health professionals and managers. The timing of this guidance is important, it is vital that people are aware what has been proven to work. We are aware that new evidence will come along which may contradict or add to some of our recommendations, however this is an important start in giving health providers and managers evidence-based recommendations for limiting the spread of infection. The document contains explanation, evidence and a glossary of terms (Appendix 1). If you simply want to look at the recommendations, please see the executive summary section. Along with this document we are publishing materials for patients, carers and members of the public because it is vital that we all have access to guidance and understand our individual role in reducing COVID-19 spread in hospitals and community. The coronavirus disease 2019 (COVID-19) global pandemic, first detected in Wuhan, China has affected more than 130 million people [[1]COVID-19 Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU)". ArcGIS. Johns Hopkins University. Available at: https://gisanddata.maps.arcgis.com/apps/opsdashboard/index.html#/bda7594740fd40299423467b48e9ecf6 Last accessed 21October 2020.Google Scholar]. The disease is caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which together with its close relative SARS-CoV belongs to a B lineage of beta-coronaviruses. The virus is also related to MERS-CoV virus from C lineage which was responsible for the outbreaks of Middle East Respiratory syndrome (MERS). The first wave of the pandemic occurred amid uncertainty about the dynamics of SARS-CoV-2 transmission and the possible management options for COVID-19 patients. This resulted in confusion for HCWs and hospital managers who often received conflicting advice on how to organise care and manage infected individuals without increasing the risk of transmission to HCWs and other patients. As the evidence has emerged, we are now in a position to summarise it and provide guidance to healthcare professionals on how to prevent healthcare associated COVID-19 disease when subsequent waves or localised outbreaks occur. This guidance will be produced in two parts, each covering a different question relating to prevention of COVID-19 in health and care settings. This article is the first working party report and describes routes of SARS-CoV-2 transmission. Understanding the likelihood of transmission occurring via different routes is important, so individuals can take appropriate precautions to protect themselves and others. The authors would like to acknowledge the support from their employing institutions, which allowed time required for producing this guidance. We thank the National Institute for Health Research, University College London Hospitals Biomedical Research Centre, which partly supported Professor Peter Wilson's involvement in this guidance. We would also like to thank Aye Thar Aye and Bin Gao, who on behalf of HIS Guidelines Committee reviewed this document.