COVID-19 NHS Testing

1.What is it?

The gold standard for testing infectious diseases remains PCR testing due its high sensitivity. WHO has therefore recommended verified PCR kits for COVID-19 testing which the NHS has adopted in its guidelines. This involves a upper and/ or lower respiratory tract specimen being sent to specified labs for testing. As sample delivery can take a variable length of time, once in the lab, the results may take around 48 hours to report. The results are able to specify the presence of the virus but it does not detect antibodies to detect if the patient has had the SARS-CoV-2 infection previously.

Image 1 – Visual representation of the SARS-CoV-2 virus by Roche

2. Why is it important?

Testing is vital in confirming cases of COVID-19 but since they are currently being carried out on symptomatic inpatients, those who may be infected in the public are not definitively aware of their status. This makes social distancing the most important factor in delaying the spread of COVID-19 in the community.

Once a result is available for a patient with or without COVID-19, the clinical team are able to determine if isolation is necessary to prevent the spread of a highly contagious virus. The patient must also be tested for pneumonia, influenza and other respiratory infections depending on their history as more than one type may occur simultaneously which require different routes of treatment.

3. How does it work?

  • A patient presenting with a fever and new continuous cough who has worsening symptoms on isolation after a median of 8 days arrives at the clinical site
  • The healthcare worker takes a swab from the nose, throat and/ or a bronchoalveolar lavage sample with Q tips and prepares the samples to be sent for testing
  • Samples are maintained at a temperature between 2-8 degrees celsius to maintain integrity
  • Samples are transferred to the closest designated laboratory for COVID-19 testing
  • The laboratory receives the sample and runs a reverse transcriptase PCR to detect if the SARS-CoV-2 viral RNA is present
  • Different kits will have their own protocols and equipment required to run the PCR
  • The result is reported to the department with the associated patients
  • Management will depend on the severity of the patient’s symptoms

The main suppliers of SARS-CoV-2 PCR testing kits are ROCHE, ThermoFisher and Qiagen in the UK

References

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