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 6.41 , back of head: 10 6.81 and bristles: 10 6.63 TCID 50 /ml. Following air-drying of 12 (fixation) and 24 h, titers of ≤ 10 2.5 , 10 3.75 , and 10 2.72 TCID 50 /ml were found in the respective groups, with a detection limit of 10 2.5 TCID 50 /ml. For H1N1, immediately after contamination, the following average titers could be recovered: fixation: 10 5.53 , back of head: 10 5.97 and bristles: 10 5.75 TCID 50 /ml. Following air-drying of 8 (fixation) and 24 h, titers were ≤ 10 2.5 , 10 3.63 , and 10 3.53 TCID 50 /ml in the respective group, again with 10 2.5 TCID 50 /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.