Staff testing

Covid-19 Staff Testing Process – Standard Operating Procedure

  • Staff testing is co-ordinated by RCHT on behalf of the whole health community for Cornwall

  • There are currently 30 tests available each day, including weekends, with a potential for additional capacity in Plymouth.

  • Staff will be prioritised by CFT, and may be subject to further prioritisation within the system depending on the demand for the day (see above re testing capacity)

  • Please note: testing is only valid on the day that it is completed.

  • In the event that our referrals exceed capacity CFT will be informed by RCHT and the individuals will be considered for inclusion in the next day’s List

  • Staff who have been prioritised for testing will be required to self-isolate post testing if they are living with a family member who is symptomatic. This to be agreed with their line manager prior to testing

*requested information for staff member being referred:

(please copy and paste this template into your email)

 

Forename:

SURNAME:

Telephone Number: Individual must be contactable to book appointment

Email address:

Convenient test site: Truro or Plymouth

Job Title:

Team/Department:

Reason for request: Must include details of symptoms and date of onset of symptoms/self-isolation

Line Manager:

Line Manager’s email:

 

 

 

Auto-response to every email:

In line with current guidance, CFT will only be testing those staff members who display symptoms of Covid-19 (e.g. temperature, new continuous cough, etc) and these will be prioritised against current testing capacity in Cornwall.

Current guidance regarding self-isolating and shielding should be followed where a household member is displaying symptoms and further advice can be found here: https://www.nhs.uk/conditions/coronavirus-covid-19/self-isolation-advice/

If you have been in contact with a patient suspected or confirmed to be Covid-19 positive, your risk will be minimal providing correct PPE advice has been followed. Further advice can be found here: https://intranet.cornwallft.nhs.uk/personal-protective-equipment or speak with your line manager

If you are concerned about protecting a vulnerable person at home, alternative accommodation may be available so that you may continue working. Please contact your line manager or cft.travel@nhs.net and for further advice and information.

Please see CFT’s Cornavirus Staff Health and Wellbeing pages for further sources of help and support available here: https://intranet.cornwallft.nhs.uk/coronavirus-staff-health-and-wellbeing

If you have any other query in relation to Covid-19 please see the FAQ pages (https://intranet.cornwallft.nhs.uk/coronavirus-faqs) or email cft.covid19questions@nhs.net

A note on testing in its current form

There is a lot of political noise at the moment about staff testing: the argument being that this will enable us to bring unnecessarily isolated health care professionals back into the workforce. The WHO is advising us to "test test test"

 

There are two types of test, Viral RNA tests on swabs to amplify and detect viral RNA, and antibody tests, which detect previous infection. The later does is not yet widely available.

 

All tests are wrong some of the time. We can quantify how wrong with the sensitivity and specificity. Some very small studies have given us data (based on swabs on known covid in ITUs) has given us a sensitivity of 70% for PCR. As far as I can tell, we have given this a 95% specificity, on the reasonable assumption that this is similar to other RNA PCR assays.

 

But as the Reverand Thomas Bayes taught us, the predictive value of a test depends on:

1) the test (the specificity and sensitivity)

2) how likely the disease is to begin with (the pre-test probability)

 

Now the pre-test probability is hard to quantify in this outbreak. In a circular irony, we can not really predict the pretest probability because we have not been testing, and we do not know population prevalence. But we can do some thought experiments. Say a few weeks ago, the chance of a viral infection (cough and fever) being covid was 5%, then the positive predictive value of RNA PCR would have been 42%: ie, if you tested positive, then there was only a 46% chance of this being covid. The negative predictive value is excellent at this stage:  98% (given sensitivity and specificity above and 5% pretest prob).

 

When we are at "peak covid" I suspect that the chance of a viral infection being covid is very high, perhaps even 90% (so 9 out of 10 cough and fever presentations are Covid and not another cause). At this pretest probability the negative predictive value is 26%. We want to bring back our viral NHS colleagues so that they can work: but out of every 100 negative tests, we would falsely reassure 74 to continue working with covid.

 

At a 50% prevalence​ (so 50% of symptomatic viral presentations being Covid) the negative predictive value is 76%: so we would falsely reassure 24% of negative NHS workers that they could go ahead and act as vectors for this Pandemic.

 

This is not saying we should not "test test test", but that the information is useful from a public health, rather than an individual patient level. At the individual level, we are more concerned I might suggest, about diagnosis of acute respiratory distress, than Covid per se. For those with any viral symptoms, self isolation is the only rational course of action.

Alex Burns

Royal Cornwall Hospital

Truro

Cornwall TR1 3LJ

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