The new Covid surge in Chile shows how vulnerable the UK is until we’re fully vaccinated 

What’s going on in Chile? How can a nation with one of the fastest vaccine roll-outs in the world – the vaccine poster child of south America, no less – be being hit so hard by a new wave of Covid 19?

Chile has recorded 49,542 new cases in the past week, the highest level since the pandemic began. Deaths have also started creeping up again.

Some have compared Chile with Israel, the vaccine superstar of the Middle East, where cases, hospitalisations and deaths have all fallen away sharply in the wake of its world-beating vaccination campaign. 

But it’s an erroneous comparison; apples and pears.

Israel has fully vaccinated 56 per cent of its total population, while Chile is at only 20 per cent. On the more flattering (but shaky) single dose measure, Israel is at 61 per cent compared to Chile’s 37.

The mix of vaccines the two countries are using is also very different. Israel is exclusively using the new mRNA vaccines, its rollout dominated by the super-efficacious Pfizer jab.

Chile, in contrast, is split 10 per cent Pfizer / 90 per cent Sinovac. This Chinese made vaccine is more conventional, can be stored in a regular fridge and has efficacy levels reported from trials in the range of 50.65 to 83.5 per cent. It is China’s equivalent of the Oxford AstraZeneca jab.

Worryingly, that lower 50.65 figure comes from the later stages of a trial in Brazil where the new P1 variant is now dominant. The same variant has been detected in Chile and is likely to be driving the new wave there, at least in part.

Asked about Chile at Monday’s Covid briefing, the chief medical officer Prof Chris Whitty said it was unclear what was happening there but gently warned it could happen here too.

“We absolutely need to learn from those countries that are far ahead of us or alongside us in terms of vaccine rollout,” he said.

“This is the reason we want to [unwind lockdown] in a steady way. Because the assumption is that just because you vaccinate lots of people then the problem goes away – I think Chile is quite a good corrective to that.”

Indeed if you want a comparator for Chile the UK is probably as close as you’ll get. Chile is well ahead of us on double vaccine doses but on singles we are not that far apart. 

Like Chile, our vaccine mix is also split between mRNA and conventional jabs – of which the former are thought to offer greater protection against new variants of the virus. Just as the efficacy of Sinovac appears to have slipped in the face of the Brazilian variant, the AstraZeneca jab is less effective against the not dissimilar South African version.

The three new modelling studies released by Sage on Monday further highlight the Chilean risk.

The central projections from Imperial College London and the University of Warwick suggest we will be hit by a modest but very real third wave in mid to late summer, pushing deaths back to between 100 and 250 per day. This would not be enough to overwhelm the NHS but would provide a serious public health challenge nonetheless. 

This may seem pessimistic given the current situation but some of the underlying assumptions made by the modellers seem, to my eye at least, quite optimistic. They assume 90 per cent vaccine uptake in the under 50s; they put AstraZeneca’s efficacy against infection at 63 to 65 per cent; and, most importantly of all they assume that no new variant emerges.

The third model by the London School of Hygiene and Tropical Medicine (LSHTM) reveals what happens if assumptions impacting transmission of the virus are revised down – and it’s not pretty.

It assumes AstraZeneca’s effectiveness against infection is a more modest 31 per cent. The resulting third wave then roars in late July to early August, taking deaths back to well over 1,000 a day and creating a crisis of a magnitude similar to that of January.

Many will argue that the LSHTM study takes too dim a view of the AstraZeneca vaccine’s ability to stop asymptomatic infection and they may be right. But even if you take that view, the model hints at what could happen if a new variant broke out and reduced the vaccine’s efficacy.

If that happened – and some think that as we suppress the UK variant through vaccination it becomes more likely – then we really could become the Chile of Europe.

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