July 24, 2019 

Donna M. Garren, Ph.D. 

Executive Vice President, Science and Policy

American Frozen Food Institute

2345 Crystal Drive, Suite 801 

Arlington, VA 22202 

Dear Dr. Garren: 

Thank you for your recent correspondence, on behalf of the American Frozen Food Institute, 

regarding the U.S. Food and Drug Administration (FDA) microbiological sampling assignment

for frozen berries. The FDA shares your concerns about the safety of the U.S. food supply and 

the importance of maintaining the public trust. The purpose of this letter is to address the issues

raised in your letters dated June 13, and July 2, 2019, relating to the sampling assignment, 

regulatory actions, and the release and reporting of results. We are preparing a separate response 

that will speak to our test methods and the underlying science issues you raised in these letters 

and a letter dated July 10, 2019. 

Consistent with the agency’s mission, it is important for our frozen berries assignment to 

continue as part of the FDA’s broader efforts to help ensure the safety of the U.S. food supply. 

While the primary focus of the assignment is to estimate the prevalence of hepatitis A virus 

(HAV) and norovirus (NoV) in frozen berries (raspberries, blackberries, and strawberries), we 

must take steps to protect consumers as appropriate based on our findings. As described in the 

surveillance sampling assignment, frozen berries have been implicated as the food vehicle in 

outbreaks of HAV and NoV infections in recent decades.

In August 2018, the FDA conducted outreach to industry and other stakeholders on the agency’s 

planned surveillance sampling assignment for frozen berries. As part of the outreach, we detailed 

how we would carry out the assignment, including explanations of collection methods and sites,

as well as sample analysis. We also at the time invited all stakeholders to provide feedback on 

the planned assignment as our purpose was to ensure that it would be carried out as effectively 

and efficiently as possible. Based on the feedback received, we made key changes to the 

assignment before issuing it. Those changes included limiting the sampling to individual types 

of frozen berries in finished retail packaging, removing mixed frozen berries from the scope of 

the assignment, and prioritizing early-in-the-supply-chain collection among the domestic 

samples.

After discussion of the issues outlined in your June 13 and July 2 letters, we have made 

additional modifications and clarifications to our frozen berries sampling assignment. 

First, our sample collection strategy will be modified to collect samples at distribution centers 

rather than at retail. We realize many firms may choose to place products being sampled on a 
test and hold status pending laboratory results given the long shelf-life of frozen berries. 

Therefore, removing retail collection from the sampling assignment will minimize the amount of 

product in commerce in the event a sample is determined to be positive, thereby further 

strengthening public health while minimizing market disruption.

Second, as the RT-qPCR method has undergone multi-lab validation by the FDA for the 

detection of HAV and NoV in soft fruit, this will remain the primary test under this assignment. 

However, going forward the agency will also implement Sanger sequencing as a routine 

component of this sampling assignment in order to characterize viruses present in any RT-qPCR 

positive samples. FDA will continue sharing the RT-qPCR results with the product owners or 

distributors as soon as results become available. Because an RT-qPCR positive suggests that 

product may have been in direct or indirect contact with insanitary conditions, firms with an RTqPCR positive result may want to consider reviewing their Current Good Manufacturing 

Practices and supply-chain controls for employee hygiene, illness policies, and other possible 

sources of fecal contamination. For this sampling assignment, FDA will not request initiation of 

a voluntary recall unless further characterization (i.e., the Sanger sequencing) is achieved. For 

voluntary recalls that were previously initiated and completed, FDA will finish the recall 

classifications shortly and will send classification notification letters to the firms involved.

Moving forward, results from the RT-qPCR analysis should be available within five business 

days after the FDA servicing laboratory receives the sample. Sequencing results should be 

available within 10 business days after a positive RT-qPCR result. Per Field Management 

Directive 147, Communication of Sample Analysis Results for Food Products and 

Environmental Samples,

1 if the sample is found to be contaminated, the FDA collecting division 

will promptly relay the results of such analysis by phone to the owner, operator, or agent in 

charge. The FDA will follow up with a letter to provide the Sanger result(s) to the firm, whether 

or not the virus is able to be characterized. For those that are positive, FDA will share the 

sequencing information if requested by the firm.

If the FDA detects a positive using RT-qPCR and the Sanger sequencing further characterizes a 

virus, FDA plans to request a voluntary recall. The FDA has published final guidance regarding 

public notification of recalls, which shares the agency’s current thinking on circumstances that 

would warrant such notification of the recall.2 We will continue to monitor the assignment 

closely and may reevaluate the analytical and regulatory approach to the detection of positives if 

data obtained indicate such a change is appropriate.

We are committed to ongoing communications with stakeholders about the key findings arising 

from the frozen berries sampling assignment. As with the FDA’s prior surveillance sampling 

assignments, the agency plans to share in-progress updates from the frozen berries assignment on 

the agency’s website, including the number of samples collected, as well as positive and negative 

findings. The upcoming update for the frozen berries assignment will include sample collection 

and test results from November 18, 2018, to June 28, 2019, and will include information on the 

source (domestic or import) of the samples. Please note that the progress updates do not contain 

 1 See https://www.fda.gov/media/92539/download. 2

 See https://www.fda.gov/media/110457/download.
conclusions. The agency will publish a final report on its findings and their significance on the 

FDA website once the assignment and report are complete.

In closing, we value our collaboration with AFFI and its members and share the commitment to

using the best available tools and science to further strengthen the safety of the U.S. food supply. 

Sincerely,

 /s/

Frank Yiannas

Deputy Commissioner

Food Policy and Response