First published in the IPS President's Digest 7th January 2022

Omicron and the use of respirators 
I am sure many of you have moved towards more widespread use of FFP3 in the context of the rapid transmission of the Omicron COVID variant. Certainly, its R value is probably close to 5 although this is difficult to estimate in the context of a highly vaccinated UK population.  The generation of aerosols is only one part of the puzzle that explains transmission of SARS-CoV-2. Other parts of the jigsaw include: the infectivity of the person; susceptibility of the exposed; proximity, type and duration of exposure and local environmental conditions.  The choice of mitigation strategies, including surgical masks and respirators, is complex as it needs to consider all these factors and (as is often the case with IPC) there is not a single, definitive answer.

In their statement on 22 December 2021, WHO restated their assessment of the evidence for the beneficial role of respirators in preventing transmission of SARS-CoV-2 as ‘of very low certainty’.  However, they made a new ‘conditional’ recommendation for wearing respirators in care settings where ventilation is poor or where healthcare workers preference is to use them. The ‘conditional’ descriptor means that there is uncertainty about whether the desirable effects outweigh the undesirable effects, and that the application of the recommendation is dependent on [patient/user] values, resources available and setting.

In our discussion at the IPS Management Executive Group this week we agreed that there are practical challenges and competing risks associated with decisions to extend the FFP2/3 use by staff. Rather than a wholesale introduction, decisions on the use respiratory protection are best made within the context of the hierarchy of controls and based on risk assessment.  This approach aligns with the WHO statement and the current UK COVID-19 IPC guidance.

It is important to recognise that patients are at greatest risk of acquiring COVID in healthcare settings and generally acquire infection from other patients rather than staff.  Using the hierarchy of controls to inform IP precautions prioritises the most effective controls, such as monitoring and improving ventilation and optimal hand hygiene, which protect both patients and staff.  PPE have a role to play as a mitigation strategy, but their use needs to be considered within this hierarchy.  The new NHS risk assessment tools (for both acute and community/primary care settings) provide a coherent approach to evaluating and mitigating infection risks within a hierarchy of controls framework. 

Jennie Wilson
President, Infection Prevention Society
IPSPresident@fitwise.co.uk