Experts say antibody testing is being underutilised as a tool to help Long Covid sufferers who never tested positive on a rapid antigen test (RAT).

One in five people who have had Covid-19 experience symptoms three months on and researchers and lab workers say antibody testing needs urgent funding.

RATs can be temperamental and not everyone who has got Covid-19 returns a positive rapid antigen test.

But if Long Covid symptoms develop down the track, it becomes extremely difficult to get help without a previous positive test to get the ball rolling.

That is where an antibody test comes in.

"It's that category of people that really will benefit from an antibody test because your body takes a while to generate anybodies, so it's not something that you do instantly.

Within the first few months of your infection is the best time to go and get an antibody test for prior infection.

With one in five people experiencing Long Covid symptoms three months after their infection, Brooks said people needed to take their health into their own hands.

"If something crops up down the line to do with your health and you didn't have Covid it's going to be important for our understanding of managing healthcare in general.

There are two different Covid-19 antibodies that can be detected by a blood test: one is the spike protein which shows if a person is vaccinated and the other, the nucleocapsid test.

The antibodies from the virus do not stick around as long as the antibodies from vaccinations, so it is important to get onto things quick.

The test is costly at $100 making it out of reach for many people.

With 1.6 million cases of Covid-19 since the pandemic began, NZ Institute of Medical Laboratory Science president Terry Taylor said that urgently needed to change.

"While a prior positive test helps in the diagnosis of Long Covid, it is not essential. Such diagnosis can be made on the basis of other clinical parameters."