China has stirred controversy with claims it has detected the coronavirus on packages of imported frozen food.
Frozen shrimp imported from an Ecuadorian company was banned for one week on Tuesday in a continuing series of such temporary bans.
While experts say the virus can survive for a time on cardboard and plastic containers, it remains unclear how serious a risk that poses. Like so many issues surrounding the pandemic, the matter has swiftly become politicised.
China has rejected complaints from the US and others, saying it is putting people's lives first. Experts say they generally don't consider the presence of the virus on packaging to be a significant health risk.
A look at the issue and some of the conclusions so far:
Packaging first became a major issue with outbreaks in China linked to wholesale food markets, including one in June on the outskirts of Beijing. That prompted the removal of smoked salmon from supermarket shelves and has snowballed into multiple cases nationwide involving chicken, beef and seafood from nearly two dozen countries. At some supermarkets, imported meat now comes with a sticker declaring it to be virus-free.
Infections among freight handlers have also placed suspicion on packaging. Person-to-person transmission hasn't been ruled out, however, and China has yet to release evidence that packaging was indeed the route of infection.
Trading partners, including the US, New Zealand, Canada and the EU, say they're unclear on China's methodology and have seen no solid evidence that their products carried the virus. The US has questioned whether China's crackdown is scientifically based and suggested the bans may amount to an unfair trade barrier.
Chinese foreign ministry spokesperson Zhao Lijian called the US accusations totally groundless and unreasonable.
China's measures are necessary following the spirit of putting people's lives first and protecting people's health, he said last week.