Gold-based COVID-19 testing – an update

Goldhub blog

Gold-based COVID-19 testing – an update

Trevor Keel
Consultant
World Gold Council

Posted:

As we all know, COVID-19 continues to spread around the world at an alarming rate. Some of the countries impacted earliest are beginning to cautiously emerge from lockdowns of varying scale, while the Americas are currently in the middle of the tackling the pandemic. Many countries are experiencing enormous loss to both their populations and wider economies. This is truly an unprecedented global event which will impact us all for many years to come.

As we have previously discussed, the availability of accurate, timely and cost effective testing is critical to tackling pandemics like COVID-19. Lab-based testing (so-called molecular diagnostics) has been successfully scaled up to a meaningful level in many countries, making it possible for an individual to be diagnosed quickly, sometimes even within 24-hours. Larger countries can now run hundreds of thousands of these types of tests every day, a capacity that, for example, permits the identification of a spike in infections and a rapid subsequent reaction to that outbreak. This is a huge step forward and is testament to the tireless efforts of diagnostic companies and governments around the world.

 

However, it’s clear that many non-molecular tests have not fared quite so well. Early in the pandemic there was a ‘rush to market’ of a significant number of lateral flow assays (particularly antibody tests, which can be used to determine whether someone carries COVID-19 antibodies in their blood, and thus has already been infected and fought that infection off). Many of these tests were ‘self-validated’ by their parent company and have latterly been shown to perform poorly in real-world settings. The US Food and Drug Administration (US FDA) has moved quickly to revoke emergency use authorisations awarded early in the pandemic where necessary, and removed a number of tests from the market. Other regulatory authorities around the world have acted similarly.

Thankfully, these early failures have catalysed a more focused and stringent development pathway for these important types of test. The UK Rapid Test Consortium, which is a partnership between Oxford University and leading diagnostics forms, has just announced a gold-based rapid test which has been shown to be 98.6% accurate in clinical trials. Another UK firm, Mologic, has also recently announced promising clinical data of a similar COVID-19 rapid test. Both teams will now progress their respective technologies towards market, focusing on scaling up manufacture to supply markets around the world. Importantly, Mologic has also established an independent manufacturing facility for their test which is delinked from commercial return. This site will manufacture up to 40 million devices per annum with a target price of £1 (US$1.25) per unit, ensuring the technology will be available among low income settings. If you’re interested in how this sort of test works, check out our animation below.

Rapid antigen testing is another diagnostic technology that has seen increasing attention in recent months. This technology tests for the presence of the virus directly, usually from a swab taken from a patient’s throat. Currently the US FDA has authorised two of these tests, but a number of companies around the world are developing alternative gold-based technologies. Some have published promising laboratory data, with clinical data promised in the coming weeks. These trials are critical as viral loads can be low from throat swabs, meaning test sensitivities in clinical settings can be poor as there is no amplification step involved. However, should a test of adequate sensitivity be authorised, this would represent a significant step forward in rapid testing for active infection.

Finally, one company has combined gold with a brand-new type of diagnostic technology and is currently working to develop a viable COVID-19 test. Mammoth Biosciences uses technology that is based on CRISPR nucleases which search for the presence of specific nucleic acids in a sample that are indicative of disease, and gold nanoparticles are used to generate a simple visual readout on a rapid test strip1. The company has recently announced a partnership with pharmaceutical group GSK to further develop the test, and aim to apply to the US FDA for approval before the end of the year.

The need for accurate, rapid and cost-effective gold-based testing tools is more acute now than has been at any other point throughout the COVID-19 pandemic, especially as some countries begin to emerge from lockdown. The early regulatory inadequacies have driven a more rigorous process to ensure clinical reliability, and independent results are now beginning to be reported2.

 


Footnotes

1 For an overview of this technology, and others which are beginning to gain traction, see https://www.nature.com/articles/d41586-020-02140-8

For example, early results from FIND’s COVID-19 testing programme has been published in July https://www.finddx.org/covid-19/sarscov2-eval-immuno/immuno-eval-results/