How effective are lateral flow tests?

Studies suggest that, more often than not, lateral flow tests return an accurate result.

A review of 64 studies found that they correctly identify 72% of infected people who have symptoms, and 78% within the first week of becoming ill. Furthermore, the Department of Health and Social Care claims that the Innova LFT detects more than 95% of individuals with highest ‘viral loads’ – those who are most likely to spread the virus.

However, as Dr Krishan points out, there are a few reasons why a negative lateral flow test could be wrong. “You might not be swabbing thoroughly enough, or could have a faulty test kit,” she suggests. However, she stresses, if ever a doubt goes through your mind that you might have Covid, get a PCR.

“The other thing is that after recovery from Covid it can take up to 90 days for the virus to completely be mopped up from the body. As a result, for many people the PCR test may continue to show positive during this time,” she adds.

“It is important to follow all the advice given because it is possible to be reinfected with Covid even if you have had vaccines and Covid.”

“I know people find it very frustrating and restricting at the moment but it is important that if you develop any of the symptoms that you promptly self isolate and do a PCR test because the current strain of Omicron is extremely infectious and is transmitting four times faster than the Delta variant,” Dr Krishan shares. “I urge everyone to get their vaccine and their booster. Remember that vaccines, in conjunction with regular testing, hand washing, wearing face coverings, social distancing and ventilating are the best tools we’ve got to keep ourselves and each other safe.”

Covid-19 testing: how effective and accurate are lateral flow tests taken at home?