Omicron and the diminishing spectre of long COVID

As we move on the journey to ‘Living with COVID’ and in doing so tolerate a greater risk of transmission of SARS-CoV-2 in society and in our hospitals, one of the issues is the threat of “long COVID”. A recent study suggests that long COVID is less common with Omicron than with previous variants, and that vaccination is effective in preventing long COVID.

I am pretty convinced now that the acute disease course when infected with Omicron SARS-CoV-2 is a step-change less severe than previous variants, which gives us more latitude to step down our efforts to prevent spread and focus on other priorities. Part of this assurance comes from our own review of clinical outcomes for patients with Omicron COVID-19, which showed that many cases were asymptomatic throughout, and most patients didn’t require additional care to get them through COVID-19 (such as oxygen or critical care). This is backed up by an analysis of national datasets showing similar trends.

Other than the small proportion of patients who will do badly during their acute disease with COVID-19, the thing that gives me most pause for thought is the spectre of long COVID-19. The studies mentioned above only looked at short term outcomes, and didn’t evaluate medium to long term impact from COVID-19. Based on pre-Omicron datasets, at least 10% of people who have had COVID-19 infection are still experiencing some symptoms 12 weeks later – and some estimates are much higher – even >25%. Only a small proportion of these (somewhere in the region of 1-5% of all cases) have more ongoing life-limiting ongoing symptoms. There is previous data that being vaccinated reduces the risk of long COVID-19 developing – somewhere between 15 and 50%. From a personal point of view, I know at least two people who are continuing to suffer life-limiting symptoms linked to long COVID – and it’s not a lot of fun, to say the least. I think it’s fair to say that there’s quite a bit of uncertainty about how we define long COVID and how common it is. For example, at least some of the people who are experiencing symptoms linked to long COVID are not associated with any post-viral syndrome per se – but rather long term consequences of medical interventions to treat their COVID infection (like mechanical ventilation).

A new study set out to evaluate long COVID (or “post COVID condition”) in the Omicron era by studying about 3,000 individuals in Geneva, Switzerland. This large cohort of patients were enrolled for the purposes of evaluating medium term outcomes due to COVID infection. Following exclusions, 1,807 individuals tested positive and 882 who tested negative were used as a control. Around 12% of those infected by Omicron had symptoms 12 weeks after their infection – but importantly 10% of individuals who tested negative had symptoms. Individuals infected by COVID were significantly more likely to have insomnia (2.4% vs. 2.1% of negative controls, loss or change in smell (3.5% vs. 2.7% of negative controls), and loss or change in taste (2.6% vs. 2.2% of negative controls. One crucial finding is that there was no significant difference between self-reported functional impairment in the Omicron vs. non-infected groups. As in previous studies, vaccination proved effective in reducing the chances of long COVID developing.

My key takeaways from the study are:

  • The prevalence of long COVID is lower with Omicron than with previous variants.
  • A fair chunk of longer term health conditions that are linked to COVID are actually nothing to do with COVID but would have been there anyway (this is not to underplay the impact of these issues on people’s lives!).
  • Vaccination reduces the chances of long COVID developing.

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