A narrative review of alternative transmission routes of COVID 19: what we know so far

ABSTRACT

The Coronavirus disease 19 (COVID-19) pandemics, caused by severe acute respiratory syndrome coronaviruses, SARS-CoV-2, represent an unprecedented public health challenge. Beside person-to-person contagion via airborne droplets and aerosol, which is the main SARS-CoV-2’s route of transmission, alternative modes, including transmission via fomites, food and food packaging, have been investigated for their potential impact on SARS-CoV-2 diffusion. In this context, several studies have demonstrated the persistence of SARS-CoV-2 RNA and, in some cases, of infectious particles on exposed fomites, food and water samples, confirming their possible role as sources of contamination and transmission. Indeed, fomite-to-human transmission has been demonstrated in a few cases where person-to-person transmission had been excluded. In addition, recent studies supported the possibility of acquiring COVID-19 through the fecal-oro route; the occurrence of COVID-19 gastrointestinal infections, in the absence of respiratory symptoms, also opens the intriguing possibility that these cases could be directly related to the ingestion of contaminated food and water. Overall, most of the studies considered these alternative routes of transmission of low epidemiological relevance; however, it should be considered that they could play an important role, or even be prevalent, in settings characterized by different environmental and socio-economic conditions. In this review, we discuss the most recent findings regarding SARS-CoV-2 alternative transmission routes, with the aim to disclose what is known about their impact on COVID-19 spread and to stimulate research in this field, which could potentially have a great impact, especially in low-resource contexts.

KEYWORDS:

• SARS-CoV-2
• COVID-19
• alternative routes of transmission
• fomites
• cold-chain
• food

Disclosure statement

No potential conflict of interest was reported by the authors.

Authors’ contributions

Conceptualization, G.A, A.A and V.G.; writing – original draft preparation, A.A. and V.G; writing – review and editing with input from all other authors (M.P., N.P. and F.T.), G.A., A.A and V.G; figures conceptualization and design M.P., V.G. and A.A; supervision, G.A. All authors provided critical feedback. All authors have read and agreed to the final version of the manuscript.

Availability of data and materials

Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.

Additional information

Funding

This work was funded by the National Funding for Centers of Excellence (Science Department 2023-2027, Roma Tre University, MIUR, Articolo 1, Commi 314–337, Legge 232/2016), by Next Generation EU PNRR Rome Technopole (ECS_00000024), MUR, PNRR, Missione 4 Componente 2, “Dalla ricerca all’impresa, Investimento 1.4” and by “ETICO”: Lazio Innova, POR FESR Lazio 2014 2020, Bando Gruppi di Ricerca 2020 (CUP E85F21000870002).Institutional Review Board StatementNot applicable.