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SARS-CoV-2 antigen EQA

 Covid 19 Antigen Rapid Test Diagnostic 50688136342


Image above courtesy of Wiki Commons: Covid 19 Antigen Rapid Test Diagnostic 50688136342. 


Coronavirus disease 2019 (COVID-19) remains a serious health risk in spite of the good vaccine uptake in the UK. To date, approximately 32.2% of the world's population has received one dose and 24.2% are fully vaccinated. (Coronavirus (COVID-19) Vaccinations - Statistics and Research - Our World in Data).

As it stands, almost 75% of the world's population is still at risk of being infected and the morbidity and mortality rates continue to increase since the start of the pandemic in January 2020. 

The latest figures from the World Health Organization (WHO) Coronavirus Disease (COVID-19) Dashboard show there were 209 million cases of COVID-19 worldwide, with over 4.3 million associated causes of death, by 20th August 2021. This rapid spread and increase in the number of new cases of SARS-CoV-2 infections is mainly due to person-to-person transmission.

Early laboratory diagnosis of both asymptomatic and symptomatic patients using reverse transcription polymerase chain reaction (RT-PCR) to detect SARS-CoV-2 viral RNA in patient samples plays a very important role and is considered the gold standard, but the amount of test requests for detection of SARS-CoV-2 is posing a challenge to diagnostic laboratories using RT-PCR. 

To alleviate this pressure on diagnostic laboratories, methodological simplification  of diagnostic algorithms is being adopted, thus benefitting patient care and infection control. New assays for SARS-CoV-2 are being developed and rolled out to cope with this demand.

The U.S. Food and Drug Administration (FDA) has granted emergency use authorisation (EUA) for antigen tests that can detect SARS-CoV-2, which are now being deployed for mass testing.

Antigen tests for SARS-CoV-2, albeit generally less sensitive than RT-PCR, can have a big impact on management of patients or people with suspected COVID-19, or for identification of infected people during screening. Most antigen tests are also performed outside laboratory settings.

However, proper interpretation of  the antigen test results is therefore important for accurate clinical management of infected individuals.

To provide confidence in the results produced by these tests and also to monitor the performance of institutions offering antigen testing for SARS-CoV-2, UK NEQAS for Microbiology launched a SARS-CoV-2 antigen external quality assessment (EQA) scheme in June 2021, after successful completion of 2 pilot studies in February and March 2021.

The scheme consists of 6 distributions of 4 specimens in viral transport medium simulating nasopharyngeal swabs; making it suitable for point of care settings and also for any organisation testing for SARS-CoV-2 that do not have conventional laboratory settings.

The specimens are prepared from X- ray irradiated SARS-CoV-2 virus and hence non-infectious, therefore they can be handled outside the conventional laboratory settings. Participants are allowed to return results for up to 2 methods they use.

The overall performance for participants returning results for the two pilot studies was very good, with 95.8% of participants reporting the intended results for their first method and approximately 88% of participants reporting the intended results for their second method.

The first live distribution in 21st June 21 saw an excellent overall performance of 97.5% for the first method and 93% for the second method reported by the participants, indicating an improvement in performance of the participating laboratories. 

The second live distribution was dispatched on the 23rd August 2021 with a closing date of the 6th September 2021. Data will be analysed thereafter and individual reports provided to each participant. 

The interest in this scheme is growing with more enquiries and registrations. The scheme has until now been run only in the UK, but will be available internationally after collating enough evidence on the stability of the specimens included in this scheme. 

Variants such as the Alpha, Beta, Delta etc will also be included in future distributions.

The table below illustrates the  distribution schedule and closing dates.


Distribution number

Dispatch dates

Closing dates


4th October 2021

18th October 2021


29th November 2021

6th December 2021


17th January 2022

31st  January 2022


14th March 2022

28th March 2022


Table 1: Distribution schedule for the  UK NEQAS SARS-CoV-2 Antigen EQA


Interested? Please email us email:  stating “SARS-CoV-2 antigen EQA”


Written by Dr Sanjiv Rughooputh, October 2021

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