Antibody testing to start Monday with internal GHA pilot programme

Public health officials will carry out a pilot programme to test staff at the Gibraltar Health Authority for Covid-19 antibodies, in a move that will enable them to assess how many key healthcare workers have already been exposed to the virus.

The tests, which will start on Monday, will be a precursor to a community-wide antibody testing programme that officials hope to roll out later this year.

The pilot programme will enable Public Health Gibraltar and the GHA to fine-tune critical aspects of the plan, including validating its laboratory systems and ensuring other critical aspects such as consent procedures are robust.

Antibody tests are different to the swab tests that have been carried out to date.

Swab tests offer a binary result that confirms whether a person has the virus at the time they are tested, and as such provide a limited snapshot of who is infected at any given time.

Antibody tests, on the other hand, detect Immunoglobulin G [IgG], an antibody produced by the body after it has come into contact with a new infection such as Covid-19.

The IgG antibody test will offer insight into how many people in the GHA have had the virus without realising it and developed a degree of immunity to it.

“It will tell me the potential level of immunity of my frontline staff,” said Dr Krish Rawal, the acting Medical Director.

“It will tell us how protected and resilient we are going forward.”

The issue is important because it will add to the understanding of the virus not just in Gibraltar but globally, with the anonymised data fed into research projects here and in other countries.

Gibraltar’s small size means it is possible to implement measures at a community-wide scale that other countries might struggle with, in turn enabling lessons to be drawn that might be helpful elsewhere.

Many of Gibraltar’s initiatives in the pandemic, including its Golden Hour scheme for the over 70s, have drawn international attention, not least because of the Rock’s success in containing the spread of the virus and so far ensuring no fatalities.

The antibody test is more complex than the swab and involves taking a full blood sample, which requires patient consent. GHA staff will be invited to participate and the test is not obligatory.

The GHA has to date ordered 55,000 antibody tests from Abbott Laboratories and DiaSorin, with another company, Beckmann, also due to provide tests in future.

It has so far received 5,000 tests from Abbott Laboratories and these will be used for the in-house pilot scheme at the GHA. Each test costs approximately five euros.

The remaining tests will likely not be delivered until the GHA completes the pilot scheme and, together with Public Health Gibraltar and researchers at the University of Gibraltar, draw up a detailed plan on how to roll the testing programme out to the remainder of the community.

“The public will need full information and an understanding of what we are doing, how it can help our international contribution to understanding of the virus, what a positive or negative result means, and most importantly that this is voluntary,” Dr Rawal said.

“There is a lot of work to do before a population testing programme can start, and so we have proposed after the summer, with a hope to deliver before then if at all possible.”

The chemical reagents used in the test have a limited shelf-life, which means they cannot be stockpiled for more than about two months, making timing and logistical planning critical.

But the blood tests are similar to those carried out as a matter of routine by the GHA laboratories, which would be able to process “a few hundred a day”, Dr Rawal told the Chronicle.

The biggest limitation, in fact, arises from the logistics of taking the blood samples and securing all the necessary consents and demographic information beforehand.

“Once we start, we have to be able to see it through,” Dr Rawal added.

“It’s all very time sensitive.”

And while the results of the antibody testing programme will ultimately give an indication of the level of immunity in the community, it comes with important caveats.

“We don’t know how long the antibody lasts,” Dr Rawal said, reflecting global concerns that recovering from Covid-19 does not guarantee immunity.

And even if a person is immune, they could still transmit the virus if they relax on public health measures such as hand-washing as a result of that immunity.

ASYMPTOMATIC INFECTIONS

The backdrop to this development is a slow increase in the number of people detected with the virus in recent days.

Over the past week, the targeted screening programme of frontline workers has identified 13 positive cases, including eight cross-border workers.

All the new cases work in frontline care and domiciliary posts and all are currently in self-isolation. In cases where those identified live in Spain, public health officials here have liaised with their Spanish counterparts.

The key change in the pattern of infection is that all the cases were asymptomatic, meaning they displayed none of the symptoms normally associated with Covid-19.

All 13 were unaware that they were carrying the virus and were only detected thanks to the targeted screening programme, which has so far carried out a total of 3,290 swab tests on frontline staff.

The period of infection is the same for both asymptotic people and those who suffer symptoms, and lasts around two weeks.

But although those detected over the past week were “completely fine”, they could still potentially transmit the disease, underscoring the importance of the screening programme.

The workers were all in frontline posts but employed in different locations, meaning they did not infect each other.

Dr Rawal said the results pointed to a “low-level presence of the virus in the community” and served as a reminder of the importance of following public health advice on hygiene and social distancing.

“There’s nothing fancy about this virus, it’s there in the community,” he said.

“But the best ways of protecting yourself are the non-fancy things like washing your hands, eating healthily and keeping fit and well.”

“The reason those people are asymptomatic is because their immune systems are fighting the virus, and that’s the best response.”

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