Full Breakdown
Multistate Hepatitis A Outbreak Tied to Imported Frozen Clams
By Drooid · · How we work
Background & Context
The U.S. Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) have been investigating a hepatitis A outbreak that began in late 2025. The investigation follows a pattern of previous shellfish-related hepatitis A incidents, such as the 2016 Hawaii outbreak linked to raw scallops and a 1988 outbreak linked to raw oysters.
Outbreak Data and Affected Areas
- Cases: CDC reports 37 confirmed hepatitis A infections, with illness onset ranging from July 30, 2025 to June 23, 2026.
- Hospitalizations: 30 of the 37 patients have required hospitalization; no deaths have been reported.
- Age range: Patients are between 6 and 40 years old.
- Geographic distribution:
- New York – 27 cases
- Massachusetts – 3 cases
- Minnesota – 3 cases
- Pennsylvania – 4 cases
State and local health officials interviewed patients about foods consumed 15–50 days before illness. Consumption of raw or undercooked clams was reported at rates significantly higher than the CDC FoodNet Population Survey baseline, suggesting a link to the clam product.
Official Statements and Public Health Guidance
- FDA recall: The FDA issued a warning and recall for La Serranita-brand “concha negra” (black shell) fresh frozen clams sourced from Ecuador. The product, packaged in 16-ounce plastic containers, was distributed to restaurants and retailers in Connecticut, Massachusetts, New Jersey, New York, Ohio, and Pennsylvania. The agency advises disposal of the product or contact with distributors for destruction.
- CDC advice: CDC recommends that anyone who consumed the recalled clams within the past 14 days and is not vaccinated against hepatitis A seek evaluation from a healthcare provider or local health department for possible post-exposure prophylaxis. The agency notes that freezing does not inactivate the hepatitis A virus.
- Travel and food safety context: FDA’s seafood safety program requires imported seafood to meet the same safety standards as domestic products, including Hazard Analysis Critical Control Point (HACCP) controls and import screening. Experts cited in the FDA’s March recall of Washington-state oysters and Manila clams note that low-level contamination can evade routine testing, making detection challenging.
Impact and Preventive Measures
The outbreak underscores the vulnerability of frozen shellfish to hepatitis A contamination and the importance of vaccination. Hepatitis A is vaccine-preventable; most U.S. children have been routinely vaccinated since 2006, but adults who were not immunized remain at risk. CDC emphasizes hand hygiene, safe food handling, and vaccination for travelers and consumers of high-risk foods.
Ongoing Investigation and Gaps
The CDC and FDA investigation remains active. While epidemiologic data point to the La Serranita frozen clams as the likely source, the precise contamination pathway has not been publicly detailed. No additional cases have been reported beyond the 37 identified, but CDC cautions that the true number of illnesses may be higher because some infected individuals recover without seeking medical care or testing.
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*All figures and statements are attributed to the CDC, FDA, or the cited news outlets that reported the agencies’ communications.*