Does trypsin oral spray (Viruprotect(R)/ColdZyme(R)) protect against COVID-19 and common colds or induce mutation? Caveats in medical device regulations in the European Union

Suzy Huijghebaert, Guido Vanham, Myriam Van Winckel, Karel Allegaert

Research output: Contribution to journalA1: Web of Science-articlepeer-review

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BACKGROUND: nasal or oral sprays are often marketed as medical devices (MDs) in the European Union to prevent common cold (CC), with ColdZyme ®/Viruprotect ® (trypsin/glycerol) mouth spray claiming to prevent colds and the COVID-19 virus from infecting host cells and to shorten/reduce CC symptoms as an example. We analyzed the published (pre)-clinical evidence.

METHODS: preclinical: comparison of in vitro tests with validated host cell models to determine viral infectivity. Clinical: efficacy, proportion of users protected against virus (compared with non-users) and safety associated with trypsin/glycerol.

RESULTS: preclinical data showed that exogenous trypsin enhances SARS-CoV-2 infectivity and syncytia formation in host models, while culture passages in trypsin presence induce spike protein mutants. The manufacturer claims >98% SARS-CoV-2 deactivation, although clinically irrelevant as based on a tryptic viral digest, inserting trypsin inactivation before host cells exposure. Efficacy and safety were not adequately addressed in clinical studies or leaflets (no COVID-19 data). Protection was obtained among 9-39% of users, comparable to or lower than placebo-treated or non-users. Several potential safety risks (tissue digestion, bronchoconstriction) were identified.

CONCLUSIONS: the current European MD regulations may result in insufficient exploration of (pre)clinical proof of action. Exogenous trypsin exposure even raises concerns (higher SARS-CoV-2 infectivity, mutations), whereas its clinical protective performance against respiratory viruses as published remains poor and substandard.

Original languageEnglish
Article number5066
JournalInternational Journal of Environmental Research and Public Health
Issue number10
Number of pages15
Publication statusPublished - 2021


  • COVID-19
  • Common Cold
  • European Union
  • Humans
  • Medical Device Legislation
  • Mutation
  • Oral Sprays
  • SARS-CoV-2
  • Trypsin

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