Coronaviruses Between Infection – Facts behind the News by Dr Richard Hastings

Between Infections – SARS-CoV-2

A lot has happened with the pandemic caused by the coronavirus SARS-CoV-2 since March. For example, the amount of research being performed to understand this novel virus is colossal, most notably for vaccine development but also other key aspects of SARS-CoV-2 that are poorly understood. In March 2020, Kampf et al. published a paper (1) that reviewed a collection of previous studies describing the survivability of disease-causing coronaviruses outside their hosts. We now have a published study of the survivability of SARS-CoV-2 outside its human target (2). The theme of these studies is all about the threat of coronaviruses, in particular SARS-CoV-2, present when they are not inside a body – that is, they are between infections. Viruses are obligate intracellular parasites – they need a host for long-term survival and to replicate so a ubiquitous question to virologists is: how robust is a virus when it is outside the body? Some viruses reveal themselves to be particularly fragile whilst others relatively hardy on surfaces or objects that have been contaminated by an infected person. Given the importance of the pandemic, public health authorities need an understand of this parameter for SARS-CoV-2 because it is inextricably linked with transmission of the disease.

The researchers of this latest study timed how long SARS-CoV-2 survived on surfaces and in aerosols, thus mimicking where the virus is expected to be between hosts. Predictably, SARS-CoV-2 began to perish when suspended in aerosols similar to those created by the human respiratory tract and in contact with inanimate surfaces – plastic, metal and paper. The researchers found that the stability of SARS-CoV-2 was similar to that of another, previously recognised SARS coronavirus, that had been included in the review of Kampf et al. thus supporting the conclusions of the previous paper. In this latest study, the workers demonstrated that SARS-CoV-2 remained viable and infectious in aerosols for hours and on surfaces up to days, therefore, aerosol and fomite (contaminated surface) transmission of SARS-CoV-2 is, again, seen to be plausible.

This new paper reinforces the routes of transmission of SARS viruses, now including SARS-CoV-2. These routes of transmission are associated with nosocomial and super-spreading events. In doing so the research considered here underlines the need for effective antiviral mitigation tactics that can destroy the virus and break the chain of transmission.

References:
1. Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents. Kampf, G., et al., J. Hosp. Inf., Review, 104;3, March 2020. www.journalofhospitalinfection.com/article/S0195-6701(20)30046-3/fulltext
2. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. van Doremalen et al., N. Engl. J. Med., 382;16, April 2020. www.nejm.org/doi/full/10.1056/NEJMc2004973

Dr Richard Hastings (Mirius Healthcare Regulatory & Technical Manager) – 6/5/2020.