Covid U-turn as scientists revise test efficiency: ‘Previous studies may be misleading’

Coronavirus in numbers: UK records 34,574 more cases

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A study has found that the common test may be more than 90 percent effective at detecting people at their most infectious.

It could explain why some lateral flows are coming back negative before people receive positive PCR tests.


Scientists  have claimed they found the anser to why so many lateral flows come back negative before people receive a positive PCR test result. 

They say that the LFT tests are actually more accurate than they were originally thought to be but can’t be compared to how PCRs work directly as the two tests work differently.

The scientisits found LFTs are likely more than 80 percent effective at detecting any level of infection.

They also suspect that LFTS are more than 90 percent effective at detecting the presence of coronavirus in those who are most infectious.

LFTs work by detecting material from the surface proteins of the virus.

They are highly effective at revealing positive results when someone is infectious.

But PCR tests detect the genetic material which can remain in the body for weeks after someone is not infectious anymore.










Professor Michael Mina, from the Harvard School of Public Health, said: “There is a spectrum of infectious amounts of the COVID-19 virus and we show that LFTs are likely to detect cases 90-95% of the time when people are at their most infectious.

“The tests could achieve even 100% sensitivity when viral loads are at their peak and therefore catch nearly everyone who is currently a serious risk to public health.

“It is most likely that if someone’s LFT is negative but their PCR is positive then this is because they are not at peak transmissible stage.”

Professor Irene Petersen, from University College London’s Institute of Epidemiology and Health Care said: “Previous studies comparing the reliability of lateral flow tests and PCR tests could be potentially misleading because a PCR test is a marker of having been infected at some point within a certain window of time and does not necessarily mean someone is infectious when testing positive.”




This comes after it was previously thought that LTFs effectiveness and accuracy had come under fire.

According to the Departmnet of Health and Social Care (DHSC) , testing yourself for Covid-19 with LFTs should be a “regular habit”.  

The Government recommends you test yousellf twice a week with LFTs.


Newcastle University professor of public health Allyson Pollock and Population Health Sciences Institute principal research associate Peter Roderick described the previous data available as “very limited”.

They also said there is a lack of evidence to support the use of LFTs as “green light” tests to enable activities and that the best-case scenario for the tests would be to use them to rapidly detect infection in a healthcare setting.

The experts who conducted the latest study concluded that LFTs are a reliable public health tool that should be used to curb the spread of coronavirus and help to prevent more widespread outbreaks.



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