“What happened was absolutely tragic, there's no question… we saw far too many lives lost in care homes and we mourn for everyone,” Johnson said Friday.
“I bitterly, bitterly regret every loss of life that we've had,” he added.
Addressing questions over why so many deaths were registered in care homes across the UK, the Prime Minister said he believes several factors must be considered.
The UK government's handling of coronavirus in care homes has been widely criticized.
According to the UK's Office for National Statistics (ONS), 19,394 care home resident deaths from the start of the pandemic until mid-June -- or 29.3% of all care home resident deaths -- involved Covid-19.
From March 2, of all hospital deaths involving Covid-19, 15.5% could be accounted for by care home residents, ONS said.
“I think a lot of different things came together...the governance of care homes, getting the messages across, making sure people understood what they had to do to protect against the disease,” Johnson said on Friday.
“I think we'll have to look back at the whole issue of what happened in care homes in great, great detail,” he added.