Dr Xiushan Yin | Developing Accurate and Rapid COVID Tests for People with Colour Blindness

The ongoing pandemic has created an urgent need for faster and more accurate diagnosis. To develop their rapid COVID-19 test, Dr Yin’s team created six primers: short genetic sequences that initiate replication. The team’s primers specifically match particular gene sequences in SARS-CoV-2, the virus that causes COVID-19.

If the virus is present in a sample, the primers will bind to a strand of viral genes, which will activate an enzyme to extend the primer, creating a complementary strand of the viral genes, which will later be used as a template. Next, these two strands are separated again, and the template is used to build another copy of the original gene sequence. This forms a cycle, where genes create templates and templates create copies of the gene sequence.

Over many cycles of this reaction, hydrogen ions accumulate in the sample. This makes the sample increasingly acidic, which can easily be detected with a pH strip, which changes colour. However, most tests like these can be hard to read for the hundreds of millions of people with colour blindness. As such, Dr Yin and his team wanted to create a test that would be accessible to people with colour blindness, without affecting the test’s accuracy.

To do so, they experimented with a variety of different dyes in various combinations. They chose the combination that gave the clearest contrast: a one-to-one mix of azure II to phenol red. This dye combination would turn from blue-purple to green in the presence of SARS-CoV-2, and can be clearly seen by people with colour blindness. They tested this new dye mechanism with real samples to ensure it was both sensitive and accurate.

This research provides healthcare workers and patients with a new rapid COVID test, which is far more accessible to people with colour blindness. Dr Yin’s work will support our global efforts to track and monitor COVID-19, helping to reduce transmission and keep people safe during this ongoing pandemic.