COVID-19: OMICRON OR DELTA?

Earlier we looked at the consequences of getting a positive PCR test result.  The notification of the result was received without statement of the variant.  But it is important to know whether the infection is Omicron, or some other variant such as Delta.  That is because:

• Someone who has not had Omicron can be easily infected by it, as it can easily bypass vaccines (including a booster) and prior infection from another variant.  Although vaccines make infection from Omicron less serious, best to stay vigilant and cautious to prevent an Omicron infection
  
• Someone fully vaccinated who has had Omicron is very unlikely to be re-infected by Omicron or by one of the other variants, or at least not be seriously ill.  As near to 'Freedom' as is feasible - at least until another Variant of Concern' comes along.
  

So how do we find out which variant?

TESTING METHODS

The current PCR testing looks for specific fragments of the virus, which all variants exhibit.  So PCR tests cannot currently identify and distinguish specific variants.  New testing such as this makes testing more accurate, to more reliably spot new variants, but also cannot identify which variant is present. 

In a fast-moving field, there are at least three ways to specifically identify Omicron:

1. Whole genome sequencing (WGS), following a positive PCR test result. This process can take a few days, which is obviously not ideal
2. S gene target failure: The Omicron variant of the virus has a number of mutations which mean that the S gene does not show up in PCR results. This is referred to as 'S gene dropout' or 'S gene target failure' and it can be used as marker for this variant pending the WGS results.
3. New tests such as this one published last week, which can be rolled out to all test centres
   

In the meantime WGS and S gene target failure are only being carried out at some test centres in the UK.  The results are only used for a better understanding of community prevalence of Omicron and other variants.  Not notified to individuals

SO HOW CAN WE TELL IF WE'VE HAD OMICRON?

There is currently no sure-fire way to tell if you have had Omicron.  But we can get a strong inkling of likelihood by a combination of:

• Known incidence in the local area, when such statistics are available, and
  
• The type of symptoms experienced

Known Incidence

Oxfordshire, for example, has a Dashboard of COVID-19 statistics.  This doesn't yet indicate the levels of each variant.   But after several months at around the same rate with Delta, the number of cases is now rising steeply.  Almost certainly dominated by Omicron, with Delta still in the mix, perhaps in ratio 2:1 and increasing:

Symptoms

It is possible to be infected by any variant and have little or no symptoms.  But if symptoms are strong, the top three are different between Omicron and the others:

• Delta and earlier variants:
• Continuous cough
  
• Loss of taste and smell
• High temperature
  
• Omicron:
• Like a common cold (like some other Coronaviruses)
• Sore throat
• Runny nose
• Different
• Headache
• Fatigue
  

STOP PRESS Update 28/12/21:  It is now being reported that "The first sign and symptom of Omicron could present itself in your voice, meaning you need to keep an ear out for any changes.  This is because Omicron has been linked with a hoarse or scratchy voice, after causing havoc in your throat.  You could HEAR the very first warning sign of Omicron before you feel ill"

MY OWN ASSESSMENT

In terms of symptoms:

• Tickly sore throat, not requiring any treatment, rather than a continuous cough.  Plus a scratchy voice
  
• Mild fatigue for a couple of days.  Not like flu where it is difficult to get out of bed
• No change to taste and smell
• No high temperature

In terms of local prevalence, it looks more likely to be Omicron than Delta.  Adding in the symptoms, and it's looking like a 99%+ chance of Omicron.  

Indeed this new symptom of a scratchy voice started for me the day before the positive tests, on 25th before 26th tests.  That would allow me to exit isolation a day earlier, provided I can comply with the 7-day regulations.  Based on the NHS advice published 24 December:

Tweaked to suit the actual dates:

'This means that if, for example, your symptoms started at any time on the 25th of December (even if your first positive COVID-19 test was taken on the 26th), you may take daily LFD tests from the 31st December. If your LFD test results are negative on the 31st  and 1st, and you do not have a high temperature, you may end your isolation period after the negative test result on the 1st of January." Not the second of January had I not noticed that new symptom.

So under the 7 Days rules you can exit isolation just after 0000hrs on 1st of January, not the 4th as would have been the case with the 10 Days rules.  In this case the 25th would have been defined as Day 0, day 10 as 4th January, and isolation exit on 5th.  That means 4 days earlier.

Armed with this new symptom information, I tried to edit my Test & Trace account to bring the 10-day end date back a day.  But "You cannot change information about...your symptoms."  WTF! 

I'll have to carry a copy of thsi blogpost with me on 1st, in case I get stopped.  Assuming of course that I have two negative LFTs and no high temperature.

Then it's a matter of how 'free' I can feel going out that soon.  OK if I've had Omicron.  I reckon there's a 99%+ chance it's Omicron.  But it would be good to get a definitive test.