Confusion surrounds the extent to which insurance covers people affected by Covid who have bought tickets to gigs and other major events, says Which?.
The consumer group said ticket insurance had become more attractive to people owing to the uncertainty created by the pandemic.
It said that many concertgoers believed they would have claims in a series of different scenarios.
But it warned people to check terms carefully to see what is covered.
The pandemic has led to mass cancellations of concerts, festivals and sports events.
A survey by Which? found that one in five of those asked had tickets to an event they could not attend or was cancelled owing to coronavirus between April 2020 and May 2021.
In the case of local or national lockdowns, or mandatory self-isolation, competition authorities say ticketholders should be given a refund if they choose one.
Last month, BBC News revealed how UK music fans are sitting on hundreds of thousands of tickets for postponed concerts rather than returning them.
Either way, there would be no need to have bought an insurance policy in those circumstances.
However, the situation becomes more complicated when consumers do not attend an event that may still be going ahead and are following government advice rather than a legal requirement. That may include advice not to travel outside their local area.
Not all policies analysed by Which? offered cover for similar circumstances.
Adam French, Which? consumer rights expert, said: "With more and more people tempted by ticket insurance during the pandemic, many don't know what it would cover them for and could be buying insurance assuming that it covers them for all Covid disruptions.
"Consumers should check the terms and conditions carefully to see if it's worth buying insurance and should remember that if an event is cancelled or postponed due to lockdown rules, primary ticket sellers have to offer a refund."
Ticket insurers told Which? that many customers have been able to obtain full refunds owing to their cover. At times that could include situations such as bereavement or redundancy.