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Covid-19 Primary Care Resources

What should I do if I suspect Covid-19 but my patient has negative swabs?

Advice from a Consultant in Infectious Diseases

This information is sourced from Dr Sarah Logan, Consultant in Infectious Diseases and General Medicine

Q.        I suspect Covid-19 but my patient has negative swabs, what should I do?


  • We know that combined nose and throat swab or nasopharyngeal is not a perfect test
  • It will depend on the pre test probability that the patient has Covid-19
  • It also depends on whether the swab was well taken with enough cells in the sample and whether the patient has detectable virus at the back of their nose and throat on the day the swab was taken, which will change throughout the course of the illness
  • There is a good review of Interpreting a Covid-19 test result in the BMJ
  • If the patient has clear features of Covid-19 and they are within 8 days of symptom onset then they should be told to self isolate and their contacts traced. This is even in the absence of a positive test