SARS-CoV-2

How effective is natural ventilation in preventing the spread of respiratory infection?

Guest Blogger ventilation , , , ,

Guest blogger Dr Alexander Edwards (bio below) has written a post in preparation for IPC Journal Club on Wednesday (details and registration for that here)…

Why I chose this article?

The COVID-19 pandemic highlighted the importance of ventilation in mitigating against the transmission of airborne respiratory pathogens and improving air quality in indoor environments. However, as is the case in many UK hospitals, reliance on natural ventilation as the main source of airflow in patient ward means that attainment of the recommended ventilation rates is difficult to manage. Airflow in indoor spaces is affected by external weather conditions and can lead to uncertain airflow patterns and consequently, the unexpected transport of infectious material to connecting zones. However, the effects of weather conditions on airborne transmission are often overlooked.

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COVID-19: moving the problem around the hospital?

Jon Otter (@jonotter) COVID-19 , , ,

Read an interesting study in JHI with a novel design that I thought I’d share. The study team evaluated the scale of COVID-19 outbreaks across three hospitals in Wales based on characteristics of the ward. When controlling for the things that you think might predict the scale of COVID-19 outbreaks (like speciality, number of toilets, patient age), the thing that came out as the biggest drive of outbreak size was how many patient transfers occurred into the ward. This suggests that the advice from “central command” to minimise patient moves made sense, and still makes sense to reduce the risk of transmissible infectious diseases in our hospitals.

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Evaluating the transmission dynamics of Omicron SARS-CoV-2 vs. previous variants in hospitalised inpatients

Jon Otter (@jonotter) COVID-19 , , , , , ,

Colleagues from GSTT in collaboration with the Royal Free and St. George’s have just published a new paper evaluating the transmission dynamics of Omicron SARS-CoV-2 vs. previous variants in hospitalised inpatients in Infection Prevention in Practice. The key finding is that the median days to inpatient contact conversion were significantly fewer for Omicron SARS-CoV-2 when compared with previous variants (median 3 days for Omicron vs. 4 days for previous variants).

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Having a nose into nasal photodisinfection

Jon Otter (@jonotter) Photodisinfection , , , ,

When’s the last time you picked your nose? If you’re an adult, it was very probably earlier today – the average adult picks their nose around 4 times per day (eew). And that’s picking – touching is much more frequent: on average, we touch our eyes, mouth, nose, or chin a staggering 20 times per hour (with some estimates even higher). We’ve known for a while that nasal decolonisation is a vital component in reducing the risk of staphylococcal infection. But using mupirocin as the nasal decolonisation agent has important limitations in terms of spectrum of microbiological efficacy, compliance, and antibiotic resistance. I’ve recently come across a newer technology for nasal decolonisation: nasal photodisinfection. It’s been around for ages, but hasn’t really been adopted widely. This blog provides an overview of three studies that suggest nasal photodisinfection may have a role in reducing the risk of SSI, and in preventing and treating SARS-CoV-2 infection.

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Respiratory protection for healthcare workers and SARS-CoV-2: evidence is equivocal but does that matter?

Jon Otter (@jonotter) COVID-19 , , , , , , , ,

So, a double blog day today! I couldn’t resist reading the latest statement from a UKHSA expert group on “The role of respirators and surgical masks in mitigating the transmission of SARS-CoV-2 in healthcare settings: an overview of evidence (2022)”, published yesterday, as soon as it hit my desk. “Equivocal” is a word that I try to avoid. It’s one of those ‘jargony’ and overly technical words that is best worded-around in my view. But for this, it’s about right. The evidence from well controlled clinical trials that respirators (FFP2/3 or N95s) offer superior protection to healthcare workers than surgical masks is equivocal (“open to more than one interpretation”). But does that matter? If we look to the physics of SARS-CoV-2 transmission, there is a risk that the type of small, virus-laden particles emitted by patients infected with SARS-CoV-2 could circumvent the level of protection provided by surgical masks. And so, it now seems reasonable to recommend FFP2/3 or N95s for healthcare workers caring for patients with SARS-CoV-2 (and influenza for that matter). However, given the uncertainty of the evidence base, as highlighted by this review, I can understand why some have decided to continue with a policy of surgical masks when caring for patients with SARS-CoV-2 infection in most settings.

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What the Cochrane “masks don’t work” review does (and does not) tell us

Jon Otter (@jonotter) Transmission , , , , , , , , ,

You may have seen some commentary and debate on a recently updated Cochrane review on physical interventions to interrupt the spread of respiratory viruses. I’m stepping into the debate only to clarify a few small points – and to provide an overview of what the review does (and does not) tell us. However, my firm advice is to read the review for yourself and come to your own conclusions.

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Comparing SARS-CoV-2 air and surface contamination in the first vs. second waves

Jon Otter (@jonotter) COVID-19 , , ,

Way back during the first wave of COVID-19 (April 2020), we got our swabs out and sampled surfaces and air across a range of settings in the hospital. This cross-sectional study identified SARS-CoV-2 RNA on a rather startling 52% of surfaces and 45% of air samples collected from across the hospital and some public areas. During the second wave (January 2021), we undertook a similar exercise, and identified a vastly different level of contamination with SARS-CoV-2 RNA: 5% of surfaces and 4% of air samples. What had changed between April 2020 and January 2021 to explain this difference? A whole host of things, and we don’t know for sure – but I suspect that improved testing availability and the introduction of masks for staff and patients were the most important factors.

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Omicron and the diminishing spectre of long COVID

Jon Otter (@jonotter) COVID-19 , , , ,

As we move on the journey to ‘Living with COVID’ and in doing so tolerate a greater risk of transmission of SARS-CoV-2 in society and in our hospitals, one of the issues is the threat of “long COVID”. A recent study suggests that long COVID is less common with Omicron than with previous variants, and that vaccination is effective in preventing long COVID.

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Finally, an RCT comparing N95s and medical masks to protect healthcare staff from COVID-19

Jon Otter (@jonotter) COVID-19 , , ,

Annals of Internal Medicine today published an RCT comparing the effectiveness of N95s vs. medical masks to protect healthcare staff from COVID-19. It’s a great piece of work, conducted over many years, and whilst the study has some important limitations, suggests that N95s don’t offer significantly increased protection than medical masks for healthcare staff caring for patients with confirmed or suspected COVID-19.

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Omicron COVID-19 harm and winter IPC strategy

Jon Otter (@jonotter) COVID-19 , , , ,

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).

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