Pigs not susceptible to COVID-19, studies show

Pigs and chickens are not susceptible to COVID-19, new research carried out in Germany has confirmed.

This latest research by the Friedrich-Loeffler-Institut (FLI) backs up the findings of a recent study in China.

SARS-CoV-2 is believed to have originated from bats, fist occurring in humans in China about three months ago, before becoming a pandemic. Various studies worldwide have been looking at whether it can also infect other species.

FLI started infection studies with SARS-CoV-2 (the official name for what has become known as COVID-19) in pigs, chickens, fruit bats, and ferrets several weeks ago. Initial results show that while fruit bats and ferrets are susceptible to infection, pigs and chickens are not.

The animals were inoculated nasally with SARS-CoV-2 to mimic the natural route of infection in humans via the nasopharyngeal route.

Pigs and chickens were tested due to their close contact with humans. The study looked at whether the animals become infected, whether the pathogen replicates and if the animals show symptoms of disease. Tests were also carried out to ascertain whether they excrete the pathogen, posing a potential risk to human health.

“Under experimental conditions, neither pigs nor chickens were found to be susceptible to infection with SARS-CoV-2,” the institute said. “According to the current state of knowledge, they are not affected by the virus and therefore do not pose a potential risk to human health.”

Egyptian fruit bats were tested to gain knowledge about the suspected reservoir function of bats. These animals became infected, but did not show any symptoms of disease and did not infect their fellow animals efficiently.

But the experiments showed that ferrets can be efficiently infected with SARS-CoV-2, the virus replicates well and can be transmitted to fellow animals. The susceptibility of ferrets is considered an important finding, as they could be used as model animals for human infection to test vaccines or drugs.

The final results of the studies are expected at the beginning of May.

Chinese study

Researchers in China have carried out similar work, investigating the susceptibility of ferrets and animals in close contact with humans to SARS-CoV-2.

They found that SARS-CoV-2 replicates poorly in dogs, pigs, chickens, and ducks, but efficiently in ferrets and cats. 

Where pigs, chickens, and ducks were inoculated with the virus, viral RNA was not detected in any swabs collected from these virus-inoculated animals or from naïve contact animals. All of the animals were seronegative for SARS-CoV-2 when tested with ELISA blood test after 14 days.

“These results indicate that pigs, chickens, and ducks are not susceptible to SARS-CoV-2,” the researchers.

Nonetheless, the NPA, reiterating the advice of the Animal and Plant Health Agency, is urging pig producers to adopt strict hygiene and biosecurity measures on farms.