The second round of Covid inquiry public hearings examining the UK's handling of the pandemic starts on 3 October.
Sessions will focus on the response of central government and how ministers and politicians made decisions, as well as how well Westminster worked with the devolved administrations in Scotland, Wales and Northern Ireland.
The government challenged the inquiry's request for WhatsApp messages sent to and from former prime minister Boris Johnson, but was forced to provide them by the High Court.
What is a public inquiry?
Public inquiries respond to "public concern" about events. They are established and funded by the government, but led by an independent chairperson.
An inquiry can demand evidence and compel witnesses to attend.
No-one is found guilty or innocent, but lessons learned are published. The government is not obliged to accept any recommendations.
Mr Johnson said the response would be "under the microscope".
Who is leading the Covid inquiry?
It is chaired by former judge and crossbench peer Baroness Hallett.
She previously led the inquests into the 7 July London bombings.
How does the inquiry work?
Work in four areas has already begun:
- resilience and preparedness
- core UK decision-making and political governance
- the impact of Covid on healthcare systems
- vaccines, therapeutics and antiviral treatment
Future strands will consider:
- the care sector
- government procurement and PPE
- test-and-trace
- the government's businesses and financial responses
- health inequalities
- education, children and young people
- other public services
There is no specific timescale for how long the inquiry will last.
Scotland is holding a separate inquiry.
What will the second round of public hearings cover?
The inquiry will look closely at decisions taken by the prime minister and cabinet ministers, and the advice received from civil servants and senior political, scientific and medical advisers between early January and late March 2020, when the first national lockdown was imposed.
Who gave evidence during the first public hearings?
The first public hearings, linked to the UK's resilience and preparedness, took evidence from 69 independent experts and former and current government officials and ministers.
These included former health secretaries Jeremy Hunt and Matt Hancock, former prime minister David Cameron and former first minister of Scotland, Nicola Sturgeon.
The inquiry also heard from the UK government's chief medical adviser during the pandemic, Sir Chris Whitty, his predecessor Prof Dame Sally Davies, and the government's chief scientific adviser, Sir Patrick Vallance.
When will the inquiry publish conclusions?
The next public hearings for the third area of examination - the impact of the pandemic on healthcare systems across the UK - are expected to run for 10 weeks from the autumn of 2024.
How can the public get involved?
Members of the public are invited to share their experiences through the inquiry's Every Story Matters project.
The Covid-19 Bereaved Families for Justice campaign group - which has criticised the government's handling of the pandemic - urged the inquiry to ensure these voices are heard.
Members of the public can also apply to attend hearings.
Why did the inquiry want ministers' WhatsApp messages?
The inquiry asked for unredacted WhatsApp messages between Mr Johnson and 40 colleagues, including former No 10 adviser Dominic Cummings, cabinet secretary Simon Case and former chancellor and current Prime Minister Rishi Sunak.
The government launched a legal challenge, arguing some of the requested material was irrelevant, but in July the High Court confirmed the documents should be provided.
However, there was a delay in providing messages sent by Mr Johnson before May 2021, because these were held on a mobile phone which had been turned off and securely locked away after a security breach.
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