Hospitals were only able to cope by relaxing regulations, allowing students to start early, retraining existing staff, encouraging recently retired staff to return, and buying private sector capacity.
A decade of cuts left the NHS and other public services "weakened" before they had to deal with the coronavirus outbreak, claims a report. This finding supports the claim that years of austerity meant that an environmental crisis became a social health and economic crisis.
In a joint inquiry by the Institute for Government and the Chartered Institute for Public Finance and Accountancy (CIPFA), the two groups found public services were "weakened after a decade of budget pressures in which quality declined, staff became more stretched, buildings were poorly maintained, and vital equipment went unbought".
The report, How Fit Were Public Services For Coronavirus?, also hit out at Number 10 and Cabinet ministers for their poor communication, citing examples of last-minute changes during the daily Downing Street briefings which had not been properly explained to the NHS and others impacted.
Nick Davies, programme director at the Institute for Government (IfG), said: "Frontline staff have performed remarkably during the crisis, in extraordinarily difficult circumstances.
"But public services have faltered due to decisions made over the past decade. Greater investment in staff, buildings and equipment would have left services far better placed to respond to coronavirus."
Rob Whiteman, CIPFA chief executive, said: "A decade of austerity has resulted in over-stretched and under-resourced public services that were already facing rising demand before the pandemic struck.
"Covid-19 supercharged these pressures, with adult social care facing particular strain.
"In addition to meeting the additional costs resulting from the pandemic and enhancing emergency planning procedures, the government must utilise the current momentum as a catalyst for adult social care reform."
Highlighting the lack of spare staff capacity in the health service, the report said the NHS only got through the Covid-19 peak in the spring by introducing emergency measures to bring in extra nurses and doctors.
The NHS went into the crisis with 90,000 vacancies, of which 40% were for nurses, and with "fewer of almost all kinds of staff per capita than comparable countries", according to the report.
"Hospitals were only able to cope by relaxing regulations, allowing students to start early, retraining existing staff, encouraging recently retired staff to return, and buying private sector capacity," said the research paper.
The organisations said announcements by No 10 and other senior ministers "were often made without consultation with those who would be affected and with little consideration of how they would be implemented".
They added: "The announcement of changes to visitation rules and personal protective equipment (PPE) usage in hospitals on June 5 was made before NHS England guidance was available.
"This meant that frontline staff had to redesign services and explain important changes to the public without clear guidance."
One of the reasons suggested for what the report called "poorly communicated changes" was "excessive ministerial churn" with many in the Cabinet having less than a year's experience in their current roles.
But the authors of the 85-page document, published on Monday, recognised that planning for a no-deal Brexit in 2019 did in fact mean the Department of Health and Social Care had a "greater understanding" of how supply chains would be disrupted in a pandemic and had improved its stockpiles of some drugs as a result of the preparatory work.
In their recommendations, the IfG and CIPFA suggested the Government conducts more regular pandemic planning exercises, with the prime minister and health secretary taking part in such sessions within six months of taking office.
It comes after the authors concluded ministers had failed to learn lessons from Exercise Cygnus in 2016, the last major exercise to prepare for a pandemic, and were overly focused on a flu-like pandemic rather than a coronavirus outbreak, leading to a lack of suitable PPE and limited understanding of how social distancing would impact society.
They also recommended the government analyses the resilience of public services when making spending decisions, including an assessment of the ability of staffing, equipment, and buildings to cope with scenarios identified in emergency plans.
Patrick Daly is the PA political correspondent.