This post will attempt to answer the following questions:
- When is herd immunity expected to be reached?
- What impact will the UK variant B.1.1.7 have on us?
- Will there be another big surge of cases before the summer?
It was the beginning of December,1944 and, six months after the D-day invasion of Europe. Allied forces had steadily marched East towards Berlin much faster than anyone had expected. The steady flow of newsreels showing allied victories lifted morale back home for those desperate for this long and brutal war to end. Many felt it was pretty much already won. The nation began to relax.
On the morning of December, 14th the Allies were exhausted from several months of nonstop combat, supply lines were overstretched, and reconnaissance was poor due to the weather. A bigger problem was that the Allied command was overconfident, feeling they had been through the worst.
It was at that moment of extreme vulnerability that German forces mounted a total surprise offensive through the densely forested Ardennes region of Belgium and Luxembourg. The result was the deadliest battle of the war for the American military. The Germans nearly achieved their goal of splitting the allied armies, taking the port of Antwerp, and forcing a peace treaty. This was the Battle of the Bulge and it almost completely altered the course of human history.
We find ourselves in a situation that is, in many ways, analogous to early December, 1944. We have endured a war that has drained us all. We are desperate for its end. We have achieved great victories over the past six months but our vaccine supply lines have not been solidified. We are overconfident that it is almost over. In other words, we are vulnerable.
Our Battle of the Bulge is likely to hit in the coming weeks. The virus’ next offensive is going to come in the form of the B.1.1.7 variant (aka the UK variant). This version of the virus is significantly more contagious than the original one and is already spreading in the United States. If you look at case data, you will see a rapid decline in cases from its peak starting in mid January but, starting in mid-February, the case numbers plateaued at the levels we had during the summer peak.
The concern is that the numbers stopped falling because B.1.1.7 started to pick up steam.
You might respond by saying the vaccine is effective and administration has been ramping up so we’ll be fine. The problem is that we are far from having everyone vaccinated. As of the time I am writing this, close to 20% of the population will have received at least one vaccine dose. Current projections are that we will hit 70% vaccinated by July and 90% by September. It is estimated that we will need 70-85% of the population protected to reach herd immunity mark although the more contagious the variant (aka. the UK) variant the longer it may take. Approximately 30 million cases have been reported but you can’t add this to the total in its entirety because many of the previously infected are also vaccinated (like yours truly). All in all, this means that, if nearly everyone gets their vaccine (a very big if) and if we throw in the number of unvaccinated who are protected from previous infection, we should reach herd immunity by the end of the summer.
Until then, we are vulnerable. Over the next few months there will be more than enough vulnerable individuals to overwhelm hospitals and cause significant morbidity and mortality. This will include many millions in the at risk age and comorbidity groups. All of the pain, suffering, and death we have experienced over the past year is from 30-35 million cases so only a small percentage of the population needs to be infected to have a considerable impact.
In to this tinderbox throw in B.1.1.7 which is 50% more infectious than the original variant. It drove a dramatic spike in cases and the UK which has nearly the highest case fatality rate in the world. This is in spite of the fact that they were on nearly complete lockdown since mid December.
Our numbers are currently similar to where the UK was when the B.1.1.7 variant first hit them. B.1.1.7 has been doubling about every 10 days here. You can see below the shape of that curve is now exponential and has stopped the decline in total cases.
The total number of cases from the B.1.1.7 variant is not clear because we have not been sequencing enough of the variants and the sequencing takes time delaying the numbers. The concern is the rate of change as a function of sequenced cases (measuring the percentage of sequenced cases that are B.1.1.7 compensates for the low rates of sequencing). The doubling time is crucial. Nearly a year ago, I posted an article explaining the importance of exponential growth in a pandemic. You should read that to understand why the absolute numbers are less important than the rate of change. See what happens to case numbers when you double the current case count of 3034 cases (as of 3/9) every 10 days:
- 3/8: 3,034
- 3/18: 6,068
- 3/28: 12,136
- 4/7: 24,272
- 4/17: 48,544
- 4/27: 97,088
- 5/7: 194,176
- 5/17: 388,352
- 5/27: 776,704
- 6/6: 1,533,408
- 6/16: 3,106,816
- 6/26: 6,213,632
Some estimates have the doubling time at seven days. This number may change which would impact the estimates but, taking the 10 day doubling time, it is easy to see how we could have a huge surge in cases before we reach herd immunity. Our current case fatality rate is 1.8% which would translate to an additional 111,845 deaths over the next three months. The UK case fatality rate, which may more accurately reflect the mortality of B.1.1.7, was 2.8%. This would translate to an additional 173,982 deaths in the next three months but that case fatality rate is when they were on a near total lockdown. For us this would make the coming months as bad as the worst of the pandemic.
If you look at the data in Europe, the surge from B.1.1.7 happened when it crossed the threshold of accounting for 50% of cases. This same pattern happened in The Czech Republic, Germany, Norway, Finland, and Jordan. We will be there in the next few weeks and can expect similar surges. These countries are responding with stricter lockdowns. We are responding by easing and, in some places, completely removing restrictions. This is especially perplexing since we now have clear data that mask mandates and public restrictions decrease viral spread and its consequences. As the new CDC director Rochelle Walensky was quoted as saying, “We’ve seen this movie before; we know what happens when you remove masks too quickly.”
The American Army and its allies were able to push back the final German assault that winter but they did so at great cost to life, limb, and treasure. Had they known it was coming they would surely have fortified their defenses and limited those losses. Now you know what is coming. Maybe you can’t change your local government policy but you can change your behavior. You can fortify your loved ones’ defenses by pleading with them to get vaccinated and helping them schedule their appointments in any way possible. You can make sure you wear your mask in public and avoid large gatherings until you are vaccinated. You can hold on just a bit longer. The end is near but we’ve got one more hill to climb before we get there. Instead of V-E standing for Victory in Europe it will stand for Vaccinated Everyone. The party in Times Square will be just as joyous.