Work on a potential flu pandemic has been put on hold due to preparations for a no-deal Brexit, according to Wales' top medical advisor.
Resources were diverted from Operation Yellowhammer to other problems, Sir Frank Atherton testified at the Covid inquiry.
During the hearing, it was revealed that a crucial pandemic flu guidance document hadn't been updated since 2011.
A non-flu pandemic strategy had not been discussed, according to the chief medical officer.
It had been "somewhat prematurely dismissed," he claimed.
The first representative from Wales to testify before the inquiry was Sir Frank.
The Wales pandemic flu preparedness group of the Welsh government met for the final time in September 2018 and did not meet again, according to the inquiry's findings.
According to emails from July 2018, officials were worried about resources and believed that the Welsh government was at risk because of the slow pace of the review of pandemic guidance.
Progress was not occurring as quickly "as anticipated," according to a note sent to health minister Vaughan Gething at one point.
Hugo Keith, an attorney for the inquiry, argued to Sir Frank that no funds had been set aside for pandemic planning, and no more work had been done. Sir Frank concurred.
He added that he was referring to the preparations for a Brexit without a deal when he said, "The reason for that, for progress then to stall, was that resources were moved to other issues.".
"The work all stalled," he continued. ".
The Wales Pandemic Flu Preparedness Group met in September 2017 to discuss the need to modify a number of "strategic documents" in light of the results of Exercise Cygnus, a flu preparedness exercise.
Sir Frank asserted that he did not believe any of them had been updated in its entirety and said that any updates would be the result of a "UK process.". In terms of planning, he continued, the strategy was founded on a document from 2011, and the planning "hung" on a UK group revising that strategy. Everything seems to depend on the master document, which has always been viewed as the 2011 strategy, the man said. However, since everything depended on the 2011 strategy update, there was no updating of the strategy documents. ".
When Covid started, Sir Frank admitted to the inquiry that his office lacked adequate resources.
At the beginning of the pandemic, he claimed, it was "drowning in a sea of information" and "couldn't even manage emails."
