How sensitive is PCR during early stages of COVID-19 infection

how sensitive is PCR during early stages of COVID-19 infection


As you may know, COVID-19 has developed into a global pandemic infecting hundreds of thousands of people and causing thousands of deaths.

Aside from its fatality in at-risk groups, the main issue that the world is facing with this virus is the relatively long incubation period, which lasts between 6 to 14 days.

As a result, robust screening and diagnosis must be implemented.

One of the most effective ways to diagnose COVID-19 in affected patients is by taking a tissue sample (e.g. blood, saliva, sputum) and testing it.

Once the sample is in the lab, physicians use polymerase chain reaction (PCR) to identify the presence or the absence of the virus’s RNA.

This method is used across the world since PCR holds high specificity; however, how sensitive is PCR during the early phases of COVID-19 infection?

The sensitivity of PCR during early phases of COVID-19 infection

Several clinical trials were conducted to compare the sensitivity of PCR to Chest CT scan and demonstrated the superiority of the latter.

According to recent studies, PCR has the following sensitivities:

  • Pharyngeal swabs at 32% (n = 126)
  • Feces at 29% (n = 44)
  • Blood at 1% (n = 3)

This shows the limits of using PCR during the early stages of COVID-19 infection, whereas CT scan reported a 95% sensitivity but a low specificity at the same time period.

Therefore, these two diagnostic tools should be used synergetically to isolate patients with positive COVID-19 infection and properly treat them.

Unfortunately, and due to the immense need for tools, such as PCR, masks, and gloves, the world is facing a severe deficiency when it comes to medical equipment.

However, it is not all doom and gloom! Companies like everymedi are doing everything they can to supply medical equipment to several regions in the world.

This gives us hope that with the contribution of everyone, the world can get through this crisis.


Image by Tumisu from Pixabay

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