The British government’s slow response to COVID caused “one of the most important public health failures” that led to thousands of unnecessary deaths, a parliamentary report found on Tuesday.

The failure to protect its people was due to the absence of lockdown measures during the pandemic’s early stages as well as unenforced contact tracing measures. This lack of government response primarily originated from a false assumption that the greater population would not comply with these COVID measures if actually imposed, the report said.

“The U.K., along with many other countries in Europe and North America, made a serious early error in adopting this fatalistic approach and not considering a more emphatic and rigorous approach to stopping the spread of the virus as adopted by many East and Southeast Asian countries,” the 147-page inquiry said.

The report is based on testimonies from more than 50 witnesses, including former Health Secretary Matt Hancock and former government insider Dominic Cummings as well as other advisers on government policy, health and science, the Associated Press noted.

While top officials met in January 2020 to discuss COVID measures, lockdown measures were not implemented until mid-March, the report said. The “gradual and incremental approach to introducing non-pharmaceutical interventions” cost “many thousands of deaths which could have been avoided,” the report added.

Over 138,000 people have died from COVID-19 in the U.K.

“There was a desire to avoid a lockdown because of the immense harm it would entail to the economy, normal health services and society,’’ the report said. “In the absence of other strategies such as rigorous case isolation, a meaningful test-and-trace operation, and robust border controls, a full lockdown was inevitable and should have come sooner.’’

Nonetheless, the government was praised for its vaccination response. Almost 80% of people 12 and older are now fully vaccinated in the U.K., according to the Our World in Data report.

“Millions of lives will ultimately be saved as a result of the global vaccine effort in which the U.K. has played a leading part,” the report read.