Two main groups of people were caught up in the scandal.
One was people with haemophilia, and those with similar disorders, who have a rare genetic condition which means their blood does not clot properly.
In the 1970s, a new treatment was developed to replace the missing clotting agents, made from donated human blood plasma.
The second group affected include people who had a blood transfusion after childbirth, accidents and during medical treatment.
Blood used for these patients was not imported, but some of it was also contaminated, mainly with hepatitis C.
Sir Brian’s two interim reports, published in July 2022 and April 2023, made recommendations about compensation for victims and their families.
The government has said it accepts the “moral case” for compensation, and interim payouts of £100,000 each have already been made to about 4,000 survivors and bereaved partners.
Ministers have promised to address the issue of final compensation once the inquiry’s report is published. The total cost is likely to run into billions.
Clive Smith, of the Haemophilia Society, said the findings of the report was “no surprise to our community” that there was a cover up.
“Now the country knows and the world knows, there was a deliberate attempt to lie and conceal, this was systemic, by government, civil servants and healthcare professionals.”
And he said it was vital the government now acted. “Why is it in the UK we continue to have these scandals?,” he added.
“We don’t listen to the recommendations of public inquiries, and that has got to stop today”.
Prime Minister Rishi Sunak is expected to issue an apology later on Monday.
