COVID - The Third Wave

David Long
 on 
August 23, 2021

Everything looked positive in April. Cases hovered at a baseline daily rate of about 2,250, less than 0.25% out of over a million tests a day. Hospitalisation had also fallen dramatically from 40,000 to around 900 patients across the entire UK and deaths had virtually flatlined.

Just when we thought it was all over came the first indications that the Delta variant had started to take hold in the UK. The Delta variant had emerged first in India with devastating impact. In little more than a month, new cases in India exploded from around to 12,000 a day to in excess of 400,000 a day with hospitalisation and deaths following equally swiftly.

Within a few short weeks the Delta variant became dominant in the UK and the blue line in the chart below illustrates just how rapidly the Delta variant has spread. Since early April cases have increased ten-fold to over 25,000 a day and the growth is exponential currently, suggesting it is likely that case rates will keep rising to 50,000 or beyond over the coming weeks.

Understandably this sent alarm bells ringing in Whitehall and ‘Freedom Day’ once planned for 21st June was delayed by at least four weeks to give sufficient time to study the true impact of the Delta variant.

Despite the worrying growth in headline case rates, the chart above shows something far more encouraging. While the dark blue line shows how new cases are following a very similar exponential growth to previous waves, the light blue shaded area shows that hospitalisation rates have increased only very modestly. In fact, a huge gap has opened up between cases and hospitalisations.

To put this into perspective, when cases were last growing at the current rate back in early November and again in December, hospitalisation rates soared to between 18,000 and 21,000. By stark contrast hospitalisations today are around ten times lower at about 2,000 and growing modestly.

A near identical picture emerges when we look at patients in ICU, the yellow dotted line in the previous chart, plotted on the right-hand scale. ICU patients have increased to about 300 currently, but this compares to levels of between 1,500 and 2,000 at the same point in the last waves.

Thankfully death rates from COVID also remain extremely low, as shown by the orange line on the previous chart. In fact, there has been very little increase in mortality despite the rapid rise in cases.

It is clear that the relationship between cases and hospitalisation and death from COVID has changed dramatically this time around. The difference, we must conclude, comes down to vaccination. The following chart illustrates the proportion of the adult population in the UK that remains unvaccinated (in pink), relative to those with one dose (light blue) and finally double doses (in dark blue).

The speed of the programme has been remarkable and only around 15% of the adult population remain unvaccinated with these predominantly in the lowest risk groups. Equally impressive is the rate of double dose vaccination at 64% meaning that all the higher risk groups now have double dose protection.

With so many vaccinated, we might question why cases are rising so rapidly? The answer, of course, is that some 25 million children and young adults remain unvaccinated. COVID presents little or no risk to these groups, nevertheless, they can still catch and spread the virus. This remains a substantial population within which the virus can spread, particularly given the increased transmissibility of the Delta variant.

Fortunately, the spread to and within the vaccinated population remains significantly subdued. The risk has not been eliminated and some spread remains; however, vaccination is working as well as anyone might have hoped.

This view is confirmed when we look at all UK mortality and excess deaths, which is illustrated in the following chart. The blue line reflects the latest weekly mortality rate in the UK from all causes, which is hovering just below 10,000 deaths per week. The three downward spikes reflect delayed registrations over bank holidays and can be ignored. Significantly the current mortality rate in the UK is below the five-year average and this ‘negative excess deaths’ has now been recorded for more than three months. During this time the UK has experienced over 8,000 fewer deaths than is normal for this time of year.

The yellow shaded area below shows the number of deaths where COVID was recorded on the death certificate, which is now just 1% of all deaths – a dramatically different picture from the last wave.

The Office for National Statistics brings further perspective in the following comparison. COVID deaths shown in the left-hand chart are a fraction of those involving flu and pneumonia show on the right, which are also themselves significantly below the five year average.

This poses the next question: at what point does the balance of harms shift from managing the risk of COVID spread, to the impact of lockdown restrictions? To answer this question the UK government has set itself four tests when assessing the further easing of restrictions:

1. The pace of vaccine rollout – this gets a big tick with 86% single and 64% double vaccinated.

2. Hospitalisations and deaths – another significant positive with clear evidence that the vulnerable are greatly protected from severe illness due to vaccination.

3. NHS capacity. While hospitalisations have grown, they are 95% below their peak. There is clearly significant capacity within the NHS to cope with the current rate of increase.

4. New variants. Two new variants are currently of interest – the Delta plus variant and a new Lambda variant which some fear may have some vaccine resistance. However, neither at this time is having a significant impact in the UK.

Based on these tests, it seems likely that the UK Government will proceed to remove the remaining restrictions on 19th July and there is a noticeable narrative emerging, shifting from ‘managing the pandemic’, to ‘living with the virus’. Let’s hope this is the right call.