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Tuesday, December 21, 2021

Omicron variant: lessons from Denmark

Danish scientists have looked at the first 785 cases of Omicron variant in Denmark. The most important lesson is that 83% of the cases were fully vaccinated. (Mostly two doses of an mRNA vaccine). This includes 7% of the total cases that had also received a booster shot. 76% of the Danish population are fully vaccinated.

Espenhain, L., Funk, T., Overvad, M., Edslev, S.M., Fonager, J., Ingham, A.C., Rasmussen, M., Madsen, S.L., Espersen, C.H. and Sieber, R.N. (2021) Epidemiological characterisation of the first 785 SARS-CoV-2 Omicron variant cases in Denmark, December 2021. Eurosurveillance 26:2101146. doi: [Eurosurveillance: Full Text]

This is similar to the results in other countries where a large percentage of the population are vaccinated. The spread of Omicron in those countries is largely driven by infection of the vaccinated group and the only way to blunt this spread is to limit contacts among vaccinated people. That means lockdowns or partial lockdowns for everybody and that seems to be working.

As usual, the United States is going to serve as a good control on these measures since the dominant message from American government, media, and health officials is that you are pretty much okay if you are vaccinated and you just have to be a bit more carefeul. No need to change your holiday travel plans.

The cases in Denmark cover all ages groups but the 20-29 age group had the highest number of infections. Quite a few of the cases could be traced to a "seasonal gathering" of 150 people and a large concert but most others seem to be due to community transmission once the variant became established. The original cases came from people who had travelled from South Africa and other countries.

Since the identification of the first Omicron case in Denmark, a steep increase in the number of cases has been observed. A major driver of this development was a large party with young adults – a population group with more social and close connections than adults and children.

We find several reasons for concern: (i) the rapid spread shortly after introduction despite extensive contact tracing efforts, (ii) the occurrence of several superspreading events with high attack rates and (iii) the high proportion of fully vaccinated Omicron cases.

So far, there haven't been many hospitalizations or deaths due to infection with the Omicron variant but that could come later.


4 comments :

  1. Scary as hell. Why don't we hear more about this?

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    1. We’re hearing a lot about it in Canada. Ontario is in partial lockdown and Quebec is close to total lockdown. The population is near panic and Christmas get-togethers are being cancelled. Almost 90% of people older than 12 have been vaccinated in Ontario and Quebec but cases are reaching record levels.

      Where are you?

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  2. In the UK we're not locking down with the strategy of give people boosters to prevent the health service from being overwhelmed and some light guidance around mask wearing and social distancing. Essentially we ignore the number of cases and focus instead on the number of hospitalisations. We'll know in a couple weeks how well this strategy is working, but I'm pretty sure the lockdowns aren't going to work.

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  3. I don't think its spread by the vaccinated group but instead its irrelevant if one is vaccinated and since, 90%?, are vaccinated it would be they get it more. Just a correction of the math.
    The other point is it seems irrelevant if one is vac, for this virus, and possibly irrelevant in how bad it is. indeed this is the first time I know people, young people, who got it, after being in big groups, but all say its less intense then a common cold.
    If its a mutant from the original covid then why would there not be lots more to come? The important point is how bad it affects people in health or bringing death.
    I don't know the stas but America surely would not being saying being vac'd would do the trick. Something wrong here as usual.

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