The first Covid lockdown "might have been avoided" if people had been quarantined earlier, according to Chancellor Jeremy Hunt.
The former health secretary also told the Covid inquiry that additional testing could have slowed the disease's progression.
In pandemic planning, a "narrow" focus on the flu led to the assumption that viruses could not be slowed down, he claimed.
Mr. Hunt testified before the inquiry that despite the Sars and Mers outbreaks in East Asia, the UK had not drawn any lessons from the region.
He continued by saying that he wished he had done more to oppose this "groupthink" in regards to this.
Mr. Hunt was instrumental in overseeing the UK's pandemic readiness while serving as health secretary from 2012 to 2018.
He is the most recent politician to testify during the first phase of the Covid inquiry, which examines how well the UK was prepared to respond to a novel disease.
The UK was well prepared for the pandemic flu, according to Mr. Hunt in his testimony on Wednesday, but "we hadn't given nearly enough thought to other types of pandemics that could emerge" during planning exercises during his tenure.
He continued by saying that Exercise Cygnus, a government simulation of the response to a flu pandemic conducted in 2016, made no mention of testing or quarantining and used 1 point 2 million infected people as its "starting point.".
As for how the government could prevent things from getting that bad, he continued, "no questions asked at any stage," which, "in retrospect," he now wishes he had questioned at the time.
In the initial weeks of the inquiry, one important subject is starting to take center stage: why did the UK fail to plan for the possibility of trying to stop a pandemic virus from spreading?
Herd immunity was inevitably going to be the only way you could contain a virus because it spread like wildfire, Mr. Hunt told those gathered. This was a "shared assumption" across western Europe and North America.
He testified before the inquiry that South Korea, which changed its pandemic strategy in response to the outbreak of the coronavirus Mers in 2015 and took more measures to contain Covid when it appeared, had not served as a lesson.
According to him, South Korea "did not have a lockdown in the first year of the pandemic.".
He called it a "blind spot" to ignore what East Asia has to teach.
According to him, it took until the new disease was spreading at a rate of 5,000 per day in the UK before government scientific advisers adopted a "Korean approach.".
And eventually, he continued, "you were going to have to use a lockdown. With that strategy, we might have prevented that if we had taken the case much earlier. ".
Exercise Alice, a different government exercise based on the Mers outbreak, was the "only place," he continued, where the "importance of quarantining" was made abundantly clear.
The exercise, he claimed, received "very little attention, in the grand scheme of things," and he claimed he was unaware of it at the time "because it wasn't shown to me.".
In other portions of his testimony, he disclosed that, prior to Exercise Cygnus, a protocol allowed the health secretary to order the emptying of intensive care beds in order to free up nursing capacity outside of hospitals.
The chancellor requested that the protocol be changed, stating that he did not feel comfortable with the idea that one day he might be required to "flick a switch that would have led to instant deaths.".
He continued by saying that he didn't feel comfortable with someone "a long way from front line" making such a decision. He said that people who were closer to the actual situation on the ground would be better suited to make such a decision.
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