WASHINGTON, D.C. — The FDA is working on a plan to enhance the safety of fresh and frozen berries after they have repeatedly been linked to hepatitis A and norovirus outbreaks.

From 1990 to 2016, there have been four hepatitis A outbreaks and three norovirus outbreaks linked to frozen berries. Since 2011, the FDA said there have been three hepatitis A outbreaks linked to fresh berries. This includes a current outbreak linked to fresh organic strawberries.

The FDA said the issue is that viruses may be introduced to berries at various points in the supply chain. This includes infected workers, contaminated water or contaminated food contact surfaces. While they may be frozen, this only preserves the berries. It does not inactivate viruses.

Additionally, the FDA said fresh berries are generally eaten raw. This does not allow for a kill step that would eliminate pathogens.

The FDA was collecting and testing frozen berries. However, this paused at the start of the COVID-19 pandemic. This month, the FDA is planning to resume the process. The FDA hopes they can estimate the prevalence of hepatitis A and norovirus in frozen strawberries, raspberries and blackberries.

So far, the FDA said it has collected and tested more than 1,100 samples. They plan to collect and test an additional 427 to meet their goals. This doesn’t include strawberries, as they already met their collection target.

After collecting the samples, the FDA will identify sites where practices or conditions may exist that constitute safety vulnerabilities. They will work with partners to develop a strategy to limit or prevent contamination throughout the supply chain.

Once the testing is complete, the FDA will release a summary report of its results.