Omicron COVID-19 harm and winter IPC strategy

We have just published an evaluation of Omicron COVID-19 harm as a research letter in the Journal of Infection. This multicentre study reported the findings of a retrospective review of 129 patients with healthcare-associated Omicron COVID-19, and found that the harm profile was very different to previous waves: a small proportion of patients required supplemental oxygen, escalation to critical care, had an extended length of stay, or died from COVID-19. This informs our winter IPC strategy: whilst COVID-19 is more than “just a cold”, the balance between direct and indirect harms from COVID-19 has shifted towards preventing indirect harms (like reduced hospital throughput and delayed diagnosis) and more of a focus on other issues (e.g. flu, Gram-negative BSIs etc).

During the Omicron wave, between December 2021 and the spring of 2022, there was another dramatic increase in patient and staff infected with SARS-CoV-2. Whilst we were in the midst of managing the wave, we noted that the harm profile associated with Omicron seemed different to previous waves: fewer patients seemed to be developing symptoms and deteriorating clinically, even in some of our most vulnerable patient areas. After the dust of the wave had settled, we decided to put some numbers to this to inform our winter IPC strategy. We teamed up with two other hospitals and reviewed the medical records of patients who had probably acquired Omicron COVID-19 in hospital.

The measures of harm that we chose were based on some national guidance: increased length of stay (>1 day) to manage their COVID-19 infection, new or increased requirement for supplemental oxygen, and admission to ICU or HDU for COVID-19. Death certificates of patients who died were reviewed to establish if COVID-19 was recorded as a direct cause of death (Part 1) or a condition contributing to the death (Part 2).

A total of 129 patients were reviewed. 86 (66.7%) of patients did not have COVID-19 symptoms. 15 (11.6%) patients had an increased length of stay, 11 (8.5%) had an increased oxygen requirement, and 2 (1.6%) required ICU or HDU attributed to COVID-19. Three (2.3%) patients had COVID-19 recorded as a direct cause of death (Part 1 of the death certificate), and four (3.1%) had COVID-19 recorded as a condition contributing to death (Part 2). A further 13 patients died but COVID-19 was not recorded on their death certificates. Logistic regression concluded that harm was not associated with age, vaccination status, or clinically vulnerable status.

I had heard people say “oh, COVID-19 is just a cold so why all this effort in preventing the spread of a cold?”, but our results to not bear this out. A proportion of patients did badly with Omicron COVID-19, and between 2 and 5% died as a direct result. And we did not evaluate harm in the medium or long term either – we know that a proportion of patients will suffer with ‘long covid‘. However, compared with previous waves, these outcomes are a step change away from harm attributed to COVID-19. By contrast, mortality associated with hospital-acquired COVID-19 during the first wave in our hospitals was 30%. The reduced harms associated with Omicron COVID-19 have also be identified in other studies (see this recent post). Whilst every patient death is a tragedy – especially those who die from HCAI, in our review of harm, between 2 and 5% of patients died from their Omicron COVID-19 infection. By contrast, a study of hospital-acquired influenza in our hospitals found that >20% of patients died.

So, what does this mean for IPC strategy over the winter? We have spent the best part of two years focusing a huge amount of time and energy (from an IPC, organisational, and societal viewpoint) on the prevention of SARS-CoV-2 transmission. This has resulted in some indirect harms. For example, hospital throughput has been affected badly, which has resulted in a big back-up of patients waiting for planned care and a reduction in capacity to care for emergency patients. Also, we have not had the capacity to focus attention on other important objectives. For example, healthcare-associated Gram-negative BSIs have increased during the pandemic. But the national objective to reduce these has stalled. And then there’s the mountains of PPE and plastic waste that we have been getting through with universal masking (and universal gloving…), which isn’t exactly helping our sustainability credentials!

How then do we begin to tackle the indirect harms associated with COVID-19 prevention measures? Asymptomatic patient testing has been a big part of our prevention strategy since widespread testing became available. But we don’t do any asymptomatic testing for other respiratory viruses (e.g. influenza). And in doing so, we have always effectively tolerated the risk of asymptomatic transmission of respiratory viruses in patients and staff, and taken a symptomatic approach to management. Given the shift in harm profile associated with COVID-19, now feels like the right time to more towards a symptomatic approach to the management of COVID-19. And with regards to PPE, we have taken the approach that every patient could have asymptomatic infection so we need to wear a mask all of the time. But as with patient testing, now feels like the right to move to a symptomatic approach to PPE too – with PPE only required to care for patients with COVID-19 symptoms. In doing this, we will be tolerating the risk of asymptomatic transmission of SARS-CoV-2 in patients and staff. But this feels like a much better balance of risks and a more sustainable approach as SARS-CoV-2 establishes itself as one of the range of respiratory viruses that we need to manage.

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