COVID-19 Nosocomial Review Group minutes: 5 February 2021

Minutes from the meeting of the Nosocomial Review Group, held on 5 February 2021.

Items and actions

  1. CNRG noted that common themes in lessons learned to date from cluster and incidents of cases in hospitals was the importance of adherence to admission testing and the importance of enabling adherence to required patient isolation pre-elective admission was also noted. The group noted the important role that higher occupancy plays in nosocomial risk and the need to minimise patient movement within and between hospitals in this regard.
  2. The importance of bed management with respect to on-going incidents and outbreaks was also noted and that the extant IPC guidance includes the need for monitoring in this regard. CNRG noted the balance needed in using available beds due to the high COVID-19 admission activity and demands on the service, and balancing risks given the potential for high attack rates associated with opening wards and the importance of the IPC and IMT team involvement in such decisions based on local risk assessment. 
  3. CNRG were updated on the first meeting of the commissioned CNRG task group on Behavioural Insights and the plan of work to support IPC adherence enablement in this regard.
  4. CNRG were informed that the UK IPC cell guidance remains the same and there is 4 country consensus that the use of FFP3 masks should remain for high risk Aerosol Generating Procedures (AGPs). The UK IPC cell has sought endorsement of this position from HSE who had confirmed this was their view, also noting that any use of FFP3 (or FFP2 in the absence of FFP3 supply) should be subject to fit testing.
  5. CNRG were presented with the latest rapid review on FRSM and FFP2/3 respirator masks. This included the WHO occupational health guidance published on 2/2/21 which recommends FFP3 for AGPs in healthcare, however CNRG also noted that the guidance includes a recommendation that workplaces with infected people in poorly ventilated environments, should provide FFP3. CNRG has asked for a view from the UK IPC cell and HSE in this regard and also recommended that NHS boards should have assurance that their hospital ventilation is in line with extant guidance and be using the hierarchy of controls to mitigate risk locally for consideration of this risk for healthcare workers. This approach is covered in the UK IPC guidance to date.
  6. It was highlighted that aerosol science studies continue to be published regarding whether coughing should be classed as an AGP, however CNRG noted that coughing does not meet the WHO definition of an AGP and also noted the outputs of the UK independent AGP panel in this regard which had been previously reviewed by CNRG. CNRG noted the importance of local risk assessment in the local context using the hierarchy of controls as defined in the IPC national guidance.
  7. CNRG also reviewed the latest pre-print study in the field which was publicised in The Guardian following a specific request from CNO (Aerosol emission from the respiratory tract: an analysis of relative risks from oxygen delivery systems, Hamilton, F. et al, Medrxiv preprint, Feb 1 2021). It was noted this was a pre-print and not subject to peer review as yet. It was stated that the study measured aerosol produced by healthy volunteers and a number of COVID-19 patients when breathing, speaking and coughing.  Aerosol produced during AGPs – Continuous Positive Airway Pressure (CPAP) and High-Flow Nasal Oxygen (HFNO) –  was also measured in the healthy volunteers.
  8. The study found that the size distribution of aerosol particles in patients with COVID-19 was very similar to healthy volunteers. Breathing, speaking and coughing all generated aerosol particles in a lognormal size distribution with the peak in the 0.5 – 1 μm diameter range and that aerosol emission with CPAP was greatly reduced compared to breathing, speaking, coughing in healthy volunteers.
  9. Further, aerosol generated by HFNO machines was found not to be of clinical relevance/thought not to pose a risk of infection, as the aerosol generated was largely from the machine, however further research is required to confirm this. It noted that for baseline measurements, speaking produced more aerosol than breathing, and wearing a fluid resistant surgical mask (FRSM) significantly reduced aerosol emission in both speaking (0.113 vs 0.038, p = 0.002), and coughing (1.40 vs 0.075, p < 0.001).
  10. CNRG highlighted that WHO recommend that medical/care procedures should be assessed based not only on their capacity to generate aerosols but also on their ability to generate infectious aerosols and an association with relevant transmission events.  This above noted experimental study did not investigate infectious aerosol production (PCR/culture viability/viral load was not investigated in the COVID-19 patients recruited) and the majority of analysis was conducted in healthy individuals.  Further research is needed on particle size and viral transmission of SARS-CoV-2. The study measured the peak aerosol emission from a cough, which may not accurately reflect the behaviour of particles in terms of dilution and particle dropout/evaporation.
  11. CNRG noted that this study does however highlights avenues for further research.  For example, similar analysis of the aerosol production of additional AGPs would add to the existing evidence base for AGP determination.  A standardised approach to aerosol sampling would be beneficial for future research and this has been recommended by the UK independent high risk AGP panel in their advice to date. CNRG noted it would include these findings and those of other aerosol studies to date, in identifying its research priorities going forward.
  12. CNRG were updated on the Lateral Flow Device (LFD) testing roll out to in-scope staff, which was nearing conclusion, and supported the plan for roll out to be extended to primary care and independent contractors, in addition to NHS24 and SAS call handling centres.
  13. CNRG were presented with the latest validated hospital onset COVID-19 data.  It was presented to group that the incidence of nosocomial infection (probable or definite hospital onset COVID-19) trends with incidence of COVID-19 in the wider population with a short delay. The incidence of hospital onset COVID-19 also aligns with the incidence of patient cases in clusters of cases in non-COVID wards.
  14. CNRG were made aware that there is limited epidemiological information in the ECOSS and RAPID dataset used for hospital onset reporting – i.e. discharge date and co-morbidity data, although alternative ways to further describe the epidemiology are being scoped.
  15. The daily Scottish figures for number of COVID-19 cases was noted to be on a downward trend, so we would expect to see a decrease in NI proportions in due course. It was noted that NI prevention is the key focus for the IPCTs in all boards and this is being further considered as to what more can be done as part of the task group work on behavioural insights.
  16. CNRG were then presented with elective and emergency hospital activity data. It was noted that activity during the pandemic has been lower than the previous three year average, however it is higher than the peak in March 2020.  It was noted that higher bed occupancy with COVID-19 impacts on nosocomial transmission, however there is some variation not accounted for with this which is being explored further.
  17. CNRG were updated on the three main COVID-19 variants of concern: VOC-202012/01, VOC-202012/02 and VUI-202101/01. Members where informed that, at time of presentation, 758 genomic sequenced cases of the Kent variant have been identified in Scotland. It is now thought that this variant is the dominant strain in Scotland. This variant has been identified in outbreaks in care homes, hospitals and community hospitals.
  18. Additionally, CNRG members were informed that 2.4 percent of samples in Scotland are Whole Genome Sequenced (WGS), including those for surveillance purposes, so the intelligence is limited to date in support of nosocomial infection analysis. CNRG noted the importance of WGS in relation to hospital outbreaks and wished to see further analysis in this regard at future meetings to better inform understanding of hospital transmission dynamics and prevention efforts.
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