CDC Report Puts Frozen Blueberries Back on the Food-Safety Checklist

A new CDC Emerging Infectious Diseases report has traced a hepatitis A outbreak in the Netherlands to frozen blueberries sold through a supermarket chain. The investigation concerns illnesses that began between November 2024 and February 2025, but its practical lesson remains relevant whenever frozen berries go straight from the freezer into smoothies, desserts or breakfast bowls.

The report is not a new blanket warning against all frozen blueberries, and it is not itself a current recall notice. Instead, it documents how investigators combined patient interviews, product tracing and laboratory testing to identify a specific batch. The article was first published on July 14, 2026, and appears in the journal’s August 2026 issue.

What the investigation found

Investigators identified 24 people infected with the same hepatitis A virus strain. Twenty-two patients reported eating a specific frozen-fruit product from one supermarket chain, while 19 reported eating frozen blueberries. Fourteen of those patients could identify a specific package.

Food-safety inspectors collected leftover frozen fruit from four households. Laboratory teams tested 66 subsamples. Hepatitis A virus RNA was detected in all 10 subsamples taken from two opened blueberry packages. The viral sequences matched the outbreak strain across the fragments obtained. No viral RNA was detected in the other 56 subsamples.

The epidemiological and laboratory findings led the retailer to recall the implicated batch, including earlier-expiry batches in the same package size. The product came from a single grower and had been repacked into one-kilogram bags for distribution in southern regions of the Netherlands. The researchers could not establish the original route of contamination, so the report does not claim that the virus entered at a particular farm, processing site or household.

That distinction matters. A confirmed link to one batch does not mean every frozen blueberry product is contaminated. It does show why traceability, recall checks and careful kitchen handling matter even when food looks clean and has been kept frozen.

Why freezing is not a kill step

Frozen fruit is often treated as ready to eat because it is washed, packaged and convenient. But freezing preserves food; it does not reliably eliminate every virus. The FDA’s frozen-berry surveillance likewise notes that fresh and frozen berries have been associated with hepatitis A and norovirus outbreaks.

The CDC report identifies consumption without prior heating as one factor that can increase the risk from contaminated berries. That is especially relevant to smoothies, chilled sauces and desserts where the fruit may never reach a cooking temperature. Washing berries may remove dirt and some surface contamination, but it should not be treated as a guaranteed way to make a recalled or contaminated product safe.

A safer routine for frozen berries

Check before using. Look at the package, brand, lot information and expiry details. If a food-safety authority, retailer or manufacturer has issued a recall, do not taste the product to decide whether it is safe. Follow the recall instructions.
Keep the cold chain intact. Buy frozen berries near the end of the shopping trip, take them home promptly and return them to the freezer. If berries have thawed substantially, follow local food-safety guidance rather than refreezing them automatically.
Prevent cross-contamination. Wash your hands with soap and water before preparing food. Keep frozen fruit, its packaging and any thawing juices away from ready-to-eat foods, clean utensils and serving dishes. Clean worktops and utensils after handling leaking or thawed packages.
Use heat when the recipe allows. For compotes, pie fillings, sauces or cooked oatmeal, heating the berries as part of the recipe adds a control step that a cold smoothie does not. Follow the recipe’s cooking instructions and do not shorten the heating stage simply because the fruit was frozen.
Be cautious with food for higher-risk people. The CDC says hepatitis A can spread through contaminated food and that foodborne outbreaks can involve fresh or frozen products. If someone in the household is unvaccinated, has chronic liver disease or is otherwise at increased risk of severe illness, check with a healthcare professional about hepatitis A vaccination and food choices.

The CDC’s hepatitis A prevention guidance identifies vaccination as the best protection and stresses thorough handwashing before preparing or eating food. That advice complements the product-level controls described in the new investigation: safe food depends on both the supply chain and what happens in the home kitchen.

The practical takeaway

Frozen blueberries remain a useful everyday ingredient, but “frozen” does not automatically mean “risk-free” or “ready to eat.” Keep packages cold, check recall information, wash hands, separate leaking or thawed fruit from ready-to-eat foods and consider cooked preparations when appropriate. Most importantly, do not confuse a published outbreak investigation with a warning about every product on the market. The report’s value is its reminder that a small, specific contamination event can be difficult to detect without careful tracing—and that simple kitchen habits help reduce the consequences when problems occur.