Omicron – Lessons Learned?

Senior clinicians up and down the country, at national level and in each small district general hospital, are meeting urgently to prepare for what’s coming. Omicron is about to massively challenge the NHS.

So what do we know about Omicron?

Back in July 2021, the UK’s Scientific Advisory Group for Emergencies tried to predict how Covid-19 might evolve.  In the event, many scientists have been surprised. Omicron has 32 mutations on the Covid-19 Spike protein which is targeted by both natural and vaccine-induced antibodies – these mutations can help Omicron evade an antibody response. 

Early after annotation of the new variant, when real-world data was lacking, scientists from Michigan State University used an AI algorithm – validated by experimental data – to predict that Omicron was twice as infectious as the Delta variant which dominated the UK.

Real-world data from South Africa showed that Omicron, unlike the Beta or Delta variants, was able to cause re-infection, suggesting it evaded antibodies generated by prior infection. However, for much of the developed world, the more important question was whether Omicron could evade vaccine-induced antibodies. 'Omicron has 32 mutations on the Covid-19 Spike protein which is targeted by both natural and vaccine-induced antibodies – these mutations can help Omicron evade an antibody response.' Click To Tweet 

Alex Sigal and colleagues then published in vitro experimental data showing that Omicron was capable of escaping antibody immunity induced by the Pfizer vaccine, resulting in a 40-fold decrease in immunity as compared to the ancestral Covid-19 virus. However, infection + vaccination provided more effective immunity. Reassuringly, vaccinated individuals were predicted to be protected from severe disease. Sigal et al’s findings were confirmed by Biontech and Pfizer.

Similarly, a German group of scientists showed that Omicron was resistant to monoclonal antibodies and reduced the neutralization efficacy of vaccine-elicited antibodies, leaving T-cell mediated immunity as an important player in protecting patients from severe infection.

What does this mean for the UK?

Importantly, in vitro experiments cannot accurately predict the complexity of what will happen on the ground in the UK. Even real-world data can be difficult to transfer outside of its specific context, because: (a) there’s significant variation between each individual’s antibody and T cell response to infection and vaccination, and (b) there’s wide divergence in vaccine coverage and mitigation policies between countries. This divergence underlies the idea that the most useful international comparator is the percentage excess deaths in each country.

We know that Omicron has a very high Reproduction number and can escape immunity from vaccines. We don’t yet know how severe infections will be in the UK (data from South Africa is poorly transferrable because they’re in summer, they’re younger and their population has a different immune profile).

However, the unprecedented acceleration of Covid-19 infections is likely to cause significant reduction in NHS staff numbers during a massive influx of moderately sick patients. Even if Omicron turns out not to be as virulent as the Delta variant, it may overwhelm the NHS and cause excess deaths by disrupting staffing, supplies and care pathways. 'Even if it doesn't turn out to be as virulent as the Delta variant, Omicron's unprecedented acceleration may overwhelm the NHS – causing death by disrupting staffing, supplies & care pathways.' Click To Tweet 

More recently, scientists at the London School of Tropical Hygiene have modelled a range of Omicron outcomes in the UK, and the results are bleak – we’re looking at tens of thousands of Covid-19 deaths over the coming months

Epidemic scenarios under no further control measures - 11th December 2021

When will we learn?

Exercise Alice predicted many of the problems we face today – two years into this pandemic. Yet again we’re in a position where vaccines provide only a partial response, and traditional public health measures (NHS bed capacity, PPE, contact tracing, mandated nurse:patient ratios) will prove decisive over the coming weeks. 

Pharmaceutical innovation cannot replace an effective universal healthcare infrastructure. That’s why today we’ve requested government agencies to inform us how they responded to consensus warnings raised by Alice'Pharmaceutical innovation cannot provide a complete answer to Omicron, and public health measures (NHS bed capacity, PPE, nurse:patient ratios) may prove decisive. Why have we degraded our universal healthcare infrastructure?' Click To Tweet 

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