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How worried should we be about the new variant of Omicron surging in Denmark?

I was looking at the data on the rate of new cases in different countries.  This showed the Faeroe Islands – a group of islands to the north of Great Britain – currently have the highest rates of infection in the world. On 25th January they reported 913 new cases, equivalent to almost 2% of the population, just in 1 day

Remembering my geography that these Islands are Danish, I checked and saw that yesterday (26th January) Denmark had second place in Europe, with approaching 1% of its population notifying as having a new infection

  • To see how these rates are so much higher than elsewhere, look at this graph:
  • The key question is what is the variant underlying these phenomenal rate rises and does it pose a risk for the rest of Europe and indeed the world?

What variants are infecting Denmark?

  • The key variant is the so-called BA.2, which has mutated from the original Omicron variant, (correctly referred to as BA.1)
  • Over a very small number of weeks BA.2 has become the most common variant in that country
  • Below is a screenshot (apologies for poor quality) of the graph from the main Danish lab showing the takeover by BA.2
  • It thus seems highly likely that BA.2 is more infectious, explaining the growth in the number of cases
  • My suspicion is that, given the close links with Denmark, the surge in the Faeroe Islands is also due to BA.2

Is there any difference in the infection caused by BA.2?

  • The variant is even more infectious but not more severe than BA.1 Omicron 
  • There hasn’t been a surge in the number of deaths from Covid-19 in Denmark 
  • Although there has been an increase in the number admitted to hospital, this is only to the extent that is expected from the increase in the number of cases
  • Further weeks of observation on this new variant are needed to confirm these reassuring observations 

What about other countries?

  • This is the strange thing!
  • In England, which has one of the best developed PCR laboratory services, there have only been 400 cases of BA.2 identified up to last week despite the first case being identified as long ago as December 6th
  • I cannot find any data about BA.2 in France, which also is in the middle of a major surge
  • The first handful of cases of BA.2 have now been identified in the USA
  • Why I think this is very strange:
    • Given the data from Denmark, a bit like the situation when Omicron (BA.1) arrived, we might have expected a very rapid takeover by the new BA.2 variant in all countries
    • This takeover has not happened yet in any other country, suggesting that outside Denmark, the cases of BA.2 were not so much more infectious than BA.1 – which has its own very high transmission rate

What about vaccination rates?

  • As frequently described in this blog, vaccines offer little protection against transmission of asymptomatic infection, but do offer some
  • For what it’s worth, Denmark (and the Faeroe Islands) have very high population rates of vaccination (2 doses) compared with the rest of the EU and the UK
  • Experts do not believe that the vaccines are any more, or any less, effective against BA.2 Omicron than they are against BA.1 Omicron 

A final comment on how is BA.2 identified?

  • First identified in the UK by the national genetic screening of samples sent for PCR testing
  • Initially considered just one of several sub-variants that typically will have arisen by chance from Omicron and possibly of little significance 
  • BA.2 has several different mutations compared to the original Omicron (called BA.1)
  • One of these differences is that the BA.1 variant of Omicron has a gene missing in its spike protein (the so-called  ‘S-gene dropout’)  – this  dropout is not seen in the BA.2 spike protein  
  • S-gene dropout is easy to detect in a laboratory, and is widely used to decide if Omicron is present
  • The worry is that the laboratories round the world have been relying on this approach to diagnose Omicron: this strategy would therefore miss detecting BA.2 Omicron

Conclusion

  • Is the BA.2 surge in Denmark a worry for the rest of Europe and the world is not easily answered
  • The infection the variant causes is no more severe and perhaps if it infects more of the population more quickly, then maybe such countries will achieve the benefit of population-wide natural immunity 
  • We also don’t know, but need to know, if this variant might lead to an increased likelihood of re-infection: ie for people who have had BA1; is there a greater chance of being reinfected with BA2 than a second dose of BA1?
  • The WHO has labelled BA.2 as a Variant of Interest as opposed to a Variant of Concern.  
  • This seems sensible, we have no need to panic but we need to keep a close eye on the rates of new cases especially if cases continue at their current high rates

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2 replies on “How worried should we be about the new variant of Omicron surging in Denmark?”

As always, thank you Alan. You write so clearly.

Today’s silly question from somebody who never did biology at school: Can BA.2 ONLY mutate from BA.1? Presumably, yes, from what you say. But if the answer is no and the rates of BA.1 were lower in Dk and the Faroes could it have mutated from delta (or other earlier variant?)

Affectionately and no doubt stupidly

Bobby

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