Receptivity to SARS-CoV-2 is the ability of an animal species to harbour the virus without necessarily developing symptoms. Susceptibility refers to the ability of the animal species to express clinical signs and/or lesions due to the virus.
The data used to define whether an animal species is receptive or susceptible to SARS-CoV-2 either come from experimental infections or from natural infections observed in the field.
Chickens, turkeys, ducks, cattle and swine: receptivity and susceptibility to SARS-CoV-2 not established or yet to be confirmed
No experimental infections have yet shown that chickens, turkeys and ducks are receptive or susceptible to SARS-CoV-2. Moreover, no data on natural infection have been recorded so far.
For cattle and swine, further studies are needed to confirm or rule out their receptivity to SARS-CoV-2, but published studies show that these animals are not susceptible to SARS-CoV-2.
Dogs and rabbits: these species are receptive to SARS-CoV-2 but their susceptibility has yet to be confirmed
While rabbits and dogs are receptive to SARS-CoV-2, their susceptibility remains to be confirmed.
In view of the very high levels of exposure to the virus (thousands of people infected with COVID-19 have been in close contact with their dogs), very few dogs have developed clinical signs under natural conditions. Furthermore, tests carried out on contact dogs have been unable to demonstrate any transmission of the virus between them. Lastly, there is currently no scientific evidence of SARS-CoV‑2 transmission from dogs to other species.
In rabbits, experimental infections tend to show the presence of lesions due to the virus, but these need to be confirmed.
Felines, ferrets, hamsters and mink: established receptivity and susceptibility to SARS-CoV-2
Among the best-known animal species:
- cats are both receptive and susceptible to SARS-CoV-2 with proven intra-species transmission, i.e. between individuals of the same species. However, there is currently no scientific evidence of SARS-CoV-2 transmission from cats to other species. As with dogs, natural infection of cats with SARS-CoV-2 occurs in a context of high viral pressure, through close contact with their owners suffering from COVID-19;
- ferrets and hamsters are receptive and susceptible to SARS-CoV-2, with proven intra-species transmission. However, at this stage there is no scientific evidence of SARS-CoV-2 transmission from these animals to other species, nor of natural infection;
- for mink, the data on natural infections reported in the Netherlands, Denmark, Spain and the United States show that this species is both receptive and susceptible to SARS-CoV-2, with proven intra-species and presumed inter-species transmission. Events in the Netherlands, and more recently in Denmark, indicate back-transmission of the virus from infected minks to humans. The Agency stresses that the occurrence of these transmission events from infected minks to humans is probably linked to the context of high viral pressure due to the high density of the animal populations in farms;
- tigers, lions and pumas in captivity in zoos are receptive and susceptible to SARS-CoV-2.
The receptivity and susceptibility of other lesser known species such as treeshrews or flying foxes (fruitbats) were also assessed by ANSES. The results are detailed in the complete opinion.
To date, domestic and wild animals have played no active role in the COVID-19 epidemic
In light of the scientific evidence currently available, the Agency confirms that to date, domestic and wild animals have not played any epidemiological role in sustaining or spreading SARS-CoV-2. At this stage, the spread is the result of human-to-human transmission by the respiratory route.
However, because the receptivity of certain animal species to SARS-CoV-2 has now been established, there is a risk of development of an animal reservoir. In this respect, ANSES recommends exercising particular vigilance with regard to situations involving contact between humans and receptive species (cats, mink, etc.), in conditions of high animal density and close proximity between animals and humans, especially in closed or confined environments. Strict hygiene measures must therefore be observed during any contact with a receptive animal: washing hands with soap after touching an animal or after cleaning its litter box, avoiding close contact with the face, wearing a mask when handling the receptive animal, etc. Any person with COVID-19 should avoid close contact with animals, without however compromising their welfare. When contact cannot be avoided (when administering treatment to animals, for example), a mask should be worn and hands should be washed before and after contact with the animals.
Similarly, vigilance is needed with regard to receptive wild animals held in captivity (mink, lions, pumas, etc.). In a context of high viral pressure, the Agency therefore reiterates the need to implement adequate safety measures in facilities rearing receptive animal species to prevent the introduction and spread of the virus.