Sales of beer in pubs fell by 56%, or £7.8bn, last year as lockdowns and trading restrictions took their toll, according to industry figures.
The report from the British Beer and Pub Association (BBPA) said the trade "cannot continue to hold out under these circumstances" and called for continued financial support even after pubs reopen.
It called for restrictions seen in previous phases of the pandemic - such as a 10pm curfew, the "substantial meal" rule or bans on mixed households - to be dropped when reopening takes place.
Philip Whitehead, chairman of the BBPA, said the present situation was "not sustainable for our sector" and urged the government to provide clarity on when drinkers could return.
Figures showed beer sales in pubs were down by 96% in the April-June period, which incorporated the first COVID-19 lockdown, compared with the same period a year earlier.
In the third quarter, despite reopening and help from a VAT cut and the Eat Out To Help Out scheme, they were still 27% off year-on-year.
For the last three months of 2020, with trading restrictions, tier rules and eventually full lockdowns taking effect, beer sales slumped by 77%.
Mr Whitehead said that with pubs in debt and with little no cash after the crisis, financial support would be needed "to bridge the gap to full recovery".
He called for a VAT cut for the sector and a business rates holiday to be extended immediately, as well as a significant beer duty cut.
"As a sector we have invested hundreds of millions in ensuring that we provide places for people to safely socialise in," Mr Whitehead said.
"When pubs reopened in July we did so safely and successfully to world leading standards.
"When pubs can reopen, the restrictions they face - ranging from the substantial meal rule to the 10pm curfew - must be removed.
"They simply destroy their ability to operate as viable businesses."