Rapid at-home Covid tests may not be as effective in detecting Omicron, US health officials say

However, the UK Health Security Agency has insisted that the lateral flow tests detect the variant just as accurately

(AFP via Getty Images)

Rapid at-home Covid tests may not be as effective in detecting Omicron compared to other coronavirus variants, US health officials have said.

In Britain, the UK Health Security Agency has insisted that the lateral flow tests detect Omicron just as accurately.

But pointing to preliminary research, the US Food and Drug Administration has suggested otherwise.

“Early data suggests that antigen tests do detect the Omicron variant but may have reduced sensitivity,” the agency said on Tuesday.

Sensitivity is a measure of how likely a test is able to detect a positive.

The warning is based on studies by the National Institutes of Health’s Rapid Acceleration of Diagnostics initiative using patient samples with live virus — analysis that “represents the best way to evaluate true test performance in the short-term,” the FDA said.

The FDA said it would continue to authorise the use of antigen tests — which work by detecting surface proteins of the Covid virus — and that individuals should continue to use them in accordance with the instructions.

Failure to do so can impact the reliability of the LFTs, which is why studies give varying estimates of their efficacy, from 40 per cent to 90 per cent.

After carrying out laboratory analysis, the UKHSA said there was “no change in performance” of the rapid tests in detecting Omicron compared to other variants, such as Delta.

It looked at five different rapid test brands that are provided to the public via NHS Test and Trace.

Real-world data on the effectiveness of the LFTs in detecting Omicron are still being collected and processed, however. The UKHSA said it would release a technical report on the devices when analysis has been completed.

Scientists have continued to advocate for the use of the lateral flow tests, which remain in high demand across the UK.

Michael Head, senior research fellow in global health at the University of Southampton, said: “Lateral flow tests are very good at producing a positive result when you are infectious (and so able to transmit the virus). This can include the day or two before symptoms develop.”