18 May 2022

Antibody testing underused to help long Covid sufferers - expert

From Checkpoint, 6:07 pm on 18 May 2022

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).

A negative result of SARS-CoV-2 antigen test is seen in this illustration photo

Photo: AFP

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," University of Auckland senior lecturer and immunologist Anna Brooks said.

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 know that you definitely did or didn't have Covid it's going to be important for our understanding of managing healthcare in general and to deal with the impacts of this virus."

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, detects other proteins only found in the virus.

Brooks said the nucleocapsid test could be the missing piece for some people experiencing symptoms months after they think they had Covid-19 but without proof.

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.

"We need to be looking at this now, we're about two and a half months post most people starting to get omicron and then we've got all the Auckland people that have had delta and like everything in the health system, they will no doubt fall off the radar unless we really, start targeting this everything we seem to do with this damn response is two months after it should have started."

Taylor said this test was not for the "worried well" to find out if they might have had Covid-19 or not.

"We've had enough of that it shouldn't be an avenue just to make money it should be a diagnostic avenue, we should be looking at the diagnostics here."

But Royal New Zealand College of General Practitioners medical director Bryan Betty was not backing it just yet.

Dr Bryan Betty

Bryan Betty Photo: https://rnzcgp.org.nz

"We know very little about it where that would become useful and how we would use in the context of someone or a set of symptoms that could be Long Covid or not, becomes a real problem and how's that validated."

There were still too many unknowns at this stage, he said.

"We need to know a lot more about Long Covid what exactly it is, what symptoms there is, what the natural history of it is, what potential treatment options are before you could start to I think make any judgement about the potential for long covid with a positive antibody."

With more than 200 symptoms associated with Long Covid, Betty said doctors were struggling to diagnose patients.

In a statement, a Ministry of Health spokesperson said: "Nucleocapsid serological testing is available in New Zealand. The tests are not funded by the Ministry of Health as part of the public health response at this time. Funding decisions are regularly reviewed depending on public health requirements and emerging evidence.

"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."

  • https://www.rnz.co.nz/news/national/467354/covid-19-update-32-new-deaths-takes-toll-over-1000-as-9570-new-community-cases-recorded