Does RAT efficacy wane with each new COVID-19 variant?

The way questions of vaccine efficacy have popped up with the emergence of each new COVID-19 variant. The same questions have been raised regarding the efficacy of at-home RAT tests. As it happens, RAT tests are probably still as effective as ever when it comes to new COVID-19 variants.

How are RATs still effective?

RATs use parts of the SARS-CoV-2 virus that aren’t inclined to change in the process of mutation. An article in the Cosmos Magazine stated that “While the spike protein on the SARS-CoV-2 virus is the site of most immunity-evading mutations, RATs instead search for the nucleocapsid proteins below the virus surface.”

“The nucleocapsid – or N protein – is where the virus’s genetic material is contained.

A chemical reaction between this protein and the solution used to perform the test is what generates a positive marker on the RAT cassette.” 

Continued efficacy and testing limitations

Are we sure RATS and PCR tests will continue to give us a mostly accurate test result? 

The Therapeutic Goods Administration (TGA) is conducting a post-market review of antigen and rapid antigen tests, including lab-based PCR testing and all rapid antigen tests.

In its announcement, the TGA noted that “RAT manufacturers are required to undertake proactive monitoring to ensure their tests are not impacted by the variants of the virus.”

When it comes to PCR tests, even though they are evaluated in highly systematic and specialised lab-based settings, they can’t account for the biology of the person undertaking the test. Individual biology can influence how a person sheds a virus. Prior vaccinations can also alter viral shedding patterns. 

This is one explanation for why even a highly accurate PCR test could fall short of a 100% accurate virus detection. 

Given the limitations of various tests, people with COVID-like symptoms who test negative on a RAT should follow up either with another test, or undergo a PCR.

Opinions or facts expressed within the content have been sourced from various news sources. While every effort has been taken to source them accurately, the pharmacy, its owners, staff or other affiliates do not take any responsibility for errors in these sources. Patients should not rely on the facts or opinions in the content to manage their own health, and should seek the advice of an appropriate medical professional. Further, the opinions or facts in the content do not reflect the opinions and beliefs of the pharmacy, its owners, staff or other affiliates.

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