Coronavirus in the Histology Laboratory

By Clifford M. Chapman bio

The current world health care concern over coronavirus (i.e., COVID-19) has generated many questions regarding many aspects of this fast spreading disease. It is important to address the subject of the affect, if any, of this disease on how we work in and operate histopathology laboratories.

An important and timely article was published online in the Journal of Histotechnology 01 March 2020. The article “Coronavirus disinfection in histopathology” by Anthony F. Henwood (1) was referenced by Gayle Callis on the NSH Open Forum and has been granted open access. Everyone is urged to read the entire article. Herein is a review to provide the essential findings of the article.

The author provides a brief history of the coronavirus outbreak and its relationship to previous outbreaks of similar coronaviruses such as Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS). Since these and coronavirus are all virus vector infectious diseases, health care professionals, including histologists, should assess their Universal Precautions procedures to ensure maximum protection while handling specimens received in the laboratory. The combination of OSHA Bloodborne Pathogens guidelines, combined with the World Health Organization (WHO) recommendations should form the basis for safe handling of tissues received in the histopathology laboratory – of which all should be considered to be infectious, as per the Universal Precautions guidelines. These standard precautions and “Summary of the Interim Laboratory Biosafety Guidelines from the CDC” are provided in the article.
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The following paragraph is taken directly from the article:

“Human-to-human transmissions of the novel coronavirus (2019-nCoV) have been described with incubation times between 2 and 10 days, facilitating its spread via droplets, contaminated hands or surfaces. There may be additional forms of transmission that are yet not determined. There are a wide range of disinfectants available that can be used to disinfect surfaces [8]. Kampf et al. [9] have noted that other coronaviruses, e.g. SARS and MERS, can persist on inanimate surfaces like metal, glass, or plastic for up to 9 days, but can be efficiently inactivated by surface disinfection procedures with 62–71% ethanol, 0.5% hydrogen peroxide, or 0.1% sodium hypochlorite within 1 min. Other biocidal agents such as 0.05% to 0.2% benzalkonium chloride or 0.02% chlorhexidine digluconate were less effective. Duan et al. [10] found that irradiation with ultraviolet light for 60 min on several coronaviruses in culture medium resulted in undetectable levels of viral infectivity.”

Based on the above information, it would be considered safe to use 70% alcohol or 1% sodium hypochlorite (i.e., bleach) as a disinfecting reagent in the laboratory to clean bench tops, workstations, etc. [Author’s opinion.] Many histology laboratories currently use such solutions.

The author provides insight into the possibilities of infection from performing frozen sections, and grossing partially fixed tissue, on tissue containing COVID-19 virus particles. The recommendations include “it appears prudent to refrain from performing frozen sections on possible cases of 2019-nCoV unless the laboratory is confident in containing aerosols in the cryostat. The same consideration should be applied to the grossing of partially fixed specimens.”

The article also discusses detailed data which evaluates the chemicals and temperatures used in histology with regard to inactivating the COVID-19 virus. The author stated “Histopathology laboratories are often fortunate in that routine histotechnology processes often inactivate many viruses, e.g. Ebola [11]… It is, therefore, appropriate to consider that the formalin-fixed paraffin-embedded tissue block would have a low risk of coronavirus infectivity.”

This data presented in the article supports the conclusion that “it is recommended that appropriate safety precautions be taken (see Tables 1 and 2) [ed. WHO and CDC guidelines] and we can be assured that formalin fixation and paraffin embedding should inactivate 2019-nCoV.”

While the current coronavirus alert is troubling and causing concern worldwide, it has provided an impetus for histopathology laboratories to (a) review their laboratory procedures regarding Universal Precautions and (b) ensure that laboratory personnel are following the procedures and utilizing appropriate and effective personal protective equipment (PPE). We thank Anthony F. Henwood and Gayle Callis for bringing this information to the attention of the histology community.