SARS-CoV-2 transmission modes: Why and how contamination occurs around shared meals and drinks?

In spite of prevention measures enacted all over the world to control the COVID-19 pandemic outbreak, including mask wearing, social distancing, hand hygiene, vaccination, and other precautions, the SARS-CoV-2 virus continues to spread globally at an unabated rate of about 1 million cases per day. The specificities of superspreading events as well as evidence of human-to-human, human-to-animal and animal-to-human transmission, indoors or outdoors, raise questions about a possibly neglected viral transmission route. In addition to inhaled aerosols, which are already recognized as key contributors to transmission, the oral route represents a strong candidate, in particular when meals and drinks are shared. In this review, we intend to discuss that significant quantities of virus dispersed by large droplets during discussions at festive gatherings could explain group contamination either directly or indirectly after deposition on surfaces, food, drinks, cutlery, and several other soiled vectors. We suggest that hand hygiene and sanitary practices around objects brought to the mouth and food also need to be taken into account in order to curb transmission.

[Covid-19: is the oral transmission route during shared meals and drinks credible?] / Covid-19 : la voie de transmission orale lors des repas et des boissons partagées est-elle crédible ?

Epidemiological and observational studies converge to suspect today a risk of contracting Covid-19 around shared meals and drinks. Contamination of table objects (plates, cutlery, glasses) or food and beverages put in the mouth is possible through droplets projected during speech or through direct contacts by dirty hands. This contamination could involve employees in the food chain, restaurant or bar staff and diners among themselves. Biopersistence on hands and cold food supports the hypothesis of contamination by the food route. The oral-digestive route is also supported by the clinical presentation of the patients, the presence of ACE2 and TMPRSS2 receptors and the SARS-CoV-2 virus found in the entire digestive tract. In addition, the reproduction of the disease via the oral route in experimental animal models confirms this hypothesis. Prevention around the food chain and around the meal by strict hygiene measures, especially hand hygiene, is essential and may be extended to other fields of application of everyday life.

Shared Food, Meals and Drinks: 10 Arguments Suggesting an Oral Transmission Route of SARS-CoV-2.

Numerous observational, epidemiologic data have suggested that the risk of COVID19 is related to shared meals or drinks. The presence of ACE2 receptors in the gastrointestinal tract supports this hypothesis. Furthermore, several patients experience gastrointestinal symptoms without any respiratory disease. The SARS-CoV-2 found on food and packaging in China and the epidemic resurgence attributed to foods are also strong indications of an oral transmission route. Unprecedented biopersistence on skin, food, and beverages supports this theory. Finally, animal models reproducing the disease by oral inoculation are additional arguments in favor of an oro-digestive route of infection.

Experimental Efficacy of the Face Shield and the Mask against Emitted and Potentially Received Particles.

There is currently not sufficient evidence to support the effectiveness of face shields for source control. In order to evaluate the comparative barrier performance effect of face masks and face shields, we used an aerosol generator and a particle counter to evaluate the performance of the various devices in comparable situations. We tested different configurations in an experimental setup with manikin heads wearing masks (surgical type I), face shields (22.5 cm high with overhang under the chin of 7 cm and circumference of 35 cm) on an emitter or a receiver manikin head, or both. The manikins were face to face, 25 cm apart, with an intense particle emission (52.5 L/min) for 30 s. The particle counter calculated the total cumulative particles aspirated on a volume of 1.416 L In our experimental conditions, when the receiver alone wore a protection, the face shield was more effective (reduction factor = 54.8%), while reduction was lower with a mask (reduction factor = 21.8%) (p = 0.002). The wearing of a protective device by the emitter alone reduced the level of received particles by 96.8% for both the mask and face shield (p = NS). When both the emitter and receiver manikin heads wore a face shield, the protection allowed for better results in our experimental conditions: 98% reduction for the face shields versus 97.3% for the masks (p = 0.01). Face shields offered an even better barrier effect than the mask against small inhaled particles (<0.3 µm-0.3 to 0.5 µm-0.5 to 1 µm) in all configurations. Therefore, it would be interesting to include face shields as used in our experimental study as part of strategies to reduce transmission within the community setting.