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Covid-19: Government U turn means positive lateral flow results will again require confirmatory PCR testing

BMJ 2021; 373 doi: https://doi.org/10.1136/bmj.n892 (Published 01 April 2021) Cite this as: BMJ 2021;373:n892

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  1. Elisabeth Mahase
  1. The BMJ

The UK government has said a positive lateral flow test result will once again have to be confirmed through polymerase chain reaction (PCR) testing,1 after previously insisting confirmation was no longer required.2

The Department of Health and Social Care said the decision has been reversed because of the importance of detecting and monitoring variants. The move comes as genotype assay testing—which is only compatible with PCR testing—has been introduced. This allows variants of concerns to be identified in half the time it usually takes, the department said.

This confirmatory testing will apply to rapid tests taken in schools. The government had previously said that a positive result in school could not be overruled by a PCR test and that the people affected would still have to isolate.3

Contact tracing will continue to be initiated after a positive lateral flow test, but people will now be able to stop isolating if a negative PCR test result is provided within two days of the lateral flow result.

The use of lateral flow tests has been a contentious matter during the covid-19 pandemic, with some arguing that they provide benefit as a way to identify positive cases rather than rule out negatives, but others warning they can provide a false sense of security.

A recent Cochrane analysis found that lateral flow test sensitivity (ability to correctly identify those with the disease or true positive rate) in symptomatic people ranged from 34% to 88%, with an average of 72%, and that they worked best in the first week after symptom onset. In people without symptoms the tests correctly identified an average of 58% of those who were infected.4

GP recommended PCR testing

In another testing change, patients can also now book PCR testing through the government website and select the reason as “a GP or other healthcare professional has asked me to get a test.” The change was introduced on 5 March and allows patients to book a test even if they don’t have one of the three main symptoms—new continuous cough, high temperature, or loss or change to sense of smell or taste.5

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References

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