Considering the role of environmental contamination in the spread of COVID-19

We know that respiratory viruses can be spread through droplets, occasionally aerosols, and contact routes (see Figure 1). But what is the relative importance of these transmission routes for the SARS-CoV-2 virus, which causes COVID-19? A new pre-print paper published yesterday provides evidence that the stability of the SARS-CoV-2 coronavirus is broadly comparable to the ‘original’ SARS coronavirus (SARS-CoV-1) on dry surfaces and in aerosols. This paper supports an important role for dry surface contamination and aerosols in the spread of SARS-CoV-2, and suggests that improved environmental persistence isn’t the key to the relative success of SARS-CoV-2 over SARS-CoV-1.

Figure 1: Transmission routes of respiratory viruses (from this review article).

covid transmission routes

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Hello Novel Coronavirus

As I’m sure you’ve heard (unless you’ve been living under a rock), there’s something going on in China: a Novel Coronavirus has been identified, associated with an outbreak affecting 44 people (one of whom has died and a small number of whom are critically unwell) in Wuhan Providence, China. Here’s what we know so far:

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Surface contamination and respiratory viruses with pandemic potential (SARS, MERS and influenza): an underestimated reservoir?

Droplet airborne direct and indirect contact figure_final

Most virologists would probably tell you that enveloped viruses are generally pretty fragile outside of their host and so wouldn’t survive for long on dry surfaces. They may well say “If you were talking about a non-enveloped virus (like norovirus) then, yes, it would probably survive on surfaces for quite a while. But enveloped viruses, no – you’d be lucky if it survived for more than a few hours.” But when I looked at the literature to investigate the potential for dry surface-mediated transmission of respiratory viruses with pandemic potential (SARS, MERS and influenza), the picture that emerged was quite different. These respiratory viruses can survive on dry surfaces for ages, and the contaminated environment may well be an underestimated reservoir for their transmission. This is summarised in a review published recently in the Journal of Hospital Infection.

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