A sample taken from a shipment of frozen chicken wings imported from Brazil to the southern city of Shenzen, China, have tested positive for coronavirus.

Local authorities also revealed that samples from packaging of frozen Ecuadorian shrimp imported into the northwestern Xian city have the same findings.

The discovery comes after Chinese authorities stepped up screenings at ports after finding traces of the coronavirus on the packaging of frozen shrimp from Ecuador in a city in eastern Anhui province.

Shenzhen’s health authorities tested everyone who are suspected to have come into contact with the potentially contaminated food products, and none of them tested positive.

On top of screening all meat and seafood containers coming into major ports, Chinese authorities have also suspended some meat imports from various origins, including Brazil.

Authorities are now tracing products from the same brand that have already been delivered and sold, and they have immediately disinfected the area were the contaminated chicken wings were stored.

The Brazilian embassy in Beijing has not responded to a request for comment, while the Ecuadorean embassy could not be reached immediately.

A China-based official at a Brazilian meat exporter said that it is hard to tell “which stage the frozen chicken got infected.”

The Shenzhen Epidemic Prevention and Control Headquarters warned the public to take precautions to reduce infection risks from imported meat and seafood.

Li Fengqin, the head of microbiology lab at the China National Center for Food Safety Risk Assessment said that the possibility of contaminated frozen food causing new infections could not be ruled out.

While viruses can survive up to two years at temperatures of minus 20 degrees Celsius, scientists has not found any strong evidence that the coronavirus that causes COVID-19 can spread via frozen food.

Health authorities from World Health Organization and the US Centers for Disease Control and Prevention back up the findings as well.