Case numbers exceeding optimistic scenario but no need for panic

Vaccine protection evident as those not immunised make up vast majority in hospital

Vaccination is the biggest factor inhibiting the spread of the virus, thanks to the administration of 1.7 million doses in July, but beyond that it is unclear what is going on. Photograph: Stephen Collins/Collins

Vaccination is the biggest factor inhibiting the spread of the virus, thanks to the administration of 1.7 million doses in July, but beyond that it is unclear what is going on. Photograph: Stephen Collins/Collins

 

With almost 30,000 Covid-19 cases recorded in July, it is clear the Delta variant of the virus is having a significant impact on Ireland’s pandemic journey.

Were it not for the variant, the pandemic would be all but over, given the effectiveness of the vaccines that have been developed.

Instead, the number of actual cases is significantly higher than was envisaged in the optimistic scenario laid out by the National Public Health Emergency Team some weeks ago.

This envisaged 9,000 cases occurring in July, a number that was subsequently revised upwards to 15,000 to take account of the early dominance of the variant.

Just over 500 patients with Covid-19 were admitted to hospital in July; again, this is well above the Nphet scenario of 160 hospitalisations, later revised to 270.

The reasons for these trends are not entirely clear, but at this stage the figures seem to be running closer to Nphet’s “central” scenario rather than its “optimistic” scenario.

Over the month, the number of Covid-19 patients in hospital each day increased significantly, from 44 to 178. The number of ICU patients more than doubled, from 14 to 39.

In spite of this, there is no sense of panic about these figures, nor does there need to be. This growth is not exponential, it appears to be slowing and it may even be plateauing.

Nphet envisaged cases and hospital/ICU numbers climbing steeply in August and September, so that under its “central 1” scenario there would be 185,000 cases in the three months to the end of September.

Social mixing

But it may be that the expected rise in cases, arising from the more transmissible variant and greater social mixing after restrictions were lifted, is occurring earlier in the period, with the peak coming sooner than was hoped.

There was a clear step change in the daily case numbers early in July but since then the daily figures resumed a pattern of steady but not spectacular growth.

Vaccination is clearly the biggest factor inhibiting the spread of the virus, thanks to the administration of 1.7 million doses in July, but beyond that it is unclear what is going on. Was it the good weather? Or the end of the school year? Or have people modified their behaviour in response to warnings about the variant?

Because the vast majority of cases are in younger people – three out of four infections are in those aged 34 and under – they tend to be milder. Yet, because of the rise in overall case numbers, more people are ending up in hospital.

Most of these cases are in unvaccinated people – though there is a clear lack of data about the types, ages and backgrounds of people who end up in hospital. Are they vaccinated? Are they in hospital due to Covid-19 or were they there for some other reason and then found to have the virus? Do they have underlying conditions?

Cases among vaccinated people have attracted disproportionate attention recently, in a clear example of cognitive bias. These are occurring because most adults are now vaccinated, and because vaccines are not 100 per cent effective.

‘Attenuated’ infection

Eoghan de Barra, infectious diseases consultant at Beaumont Hospital in Dublin, says the vast majority of patients he is seeing are unvaccinated, typically people in their 40s to 60s who chose not get immunised.

He says there have been just “a few” cases of vaccine breakthrough, in which immunised people have required treatment. Some of these involved people with impaired immune systems.

Cases involving vaccinated people tend to involved “attenuated” infection, and are less severe. De Barra says he has seen very little serious illness among young people.

“It has been amazing to witness the impact of vaccination from this end. The outcomes are a startling demonstration of how well it has worked.”

Hospitals have become better at treating Covid-19 patients since the start of the pandemic, he points out, thanks to treatments such as steroids or tocizilumab. Larger hospitals can also provide ventilation for patients without the need to enter ICU.

Across Europe, case numbers in many countries are stabilising, and even falling, as in the UK. With vaccination continuing apace, a continuation of this trend seems the most likely outcome, notwithstanding the reopening of schools and the onset of winter. We may then be left with a pandemic of the unvaccinated, with a new emphasis on personal responsibility replacing society-wide restrictions.

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