The role of toothbrush in the transmission of corona- and influenza viruses - results of an in vitro study.

Objectives: The aim of this in vitro study was to investigate viruses' stabilities on manual toothbrushes using feline coronavirus (FeCoV) as representative of coronaviruses and an Avian influenza A virus H1N1 for influenza viruses.

Material And Methods: Two viruses, FeCoV (Strain Munich; titer 107.5 TCID50/ml) and H1N1 (RE 230/90; titer 106.5 TCID50/ml), were used in this study. Manual toothbrushes were disassembled into bristles, bristle fixation, and back of the toothbrush head, contaminated with the viruses and air-dried for 24 h. In a second experiment, whole toothbrush heads were contaminated, rinsed with water (5 ml for 15 s) and then air-dried.

Results: For FeCoV, immediately after contamination, the following average titers were recovered: fixation: 10, back of head: 10 and bristles: 10 TCID/ml. Following air-drying of 12 (fixation) and 24 h, titers of ≤ 10, 10, and 10 TCID/ml were found in the respective groups, with a detection limit of 10 TCID/ml. For H1N1, immediately after contamination, the following average titers could be recovered: fixation: 10, back of head: 10 and bristles: 10 TCID/ml. Following air-drying of 8 (fixation) and 24 h, titers were ≤ 10, 10, and 10 TCID/ml in the respective group, again with 10 TCID/ml being the detection limit. In case of water rinse, no infectious virus could be recovered after 12 h.

Conclusion: Viral load of both viruses is reduced by air-drying, especially following water rinsing. Clinical relevance The toothbrush itself plays an insignificant role in the self-transmission of coronavirus and influenza virus.