Positions, transitions and herd immunity

Almost two weeks have passed from the 2020 US presidential election and the “transition” phase is taking interesting twists and turns.  The actual results and consensus suggest a new administration will be inducted on Inauguration Day (January 20, 2021). 

In the meantime, COVID-19 cases in the US are surging; peaking on November 13th with 181,196 confirmed cases in a single day.

Following a plateau at approximately 40,000 cases per day between mid-August and mid-October the country is now in the midst of an exponential growth phase.  The US has recorded over 11 million cases and almost a quarter of a million deaths.  With a 7-moving average now at approximately at 160,000 cases, unfortunately, the current administration has almost given up on controlling the virus.  The transition team has already announced a COVID taskforce, and lists dealing with the coronavirus as the number one priority on their dedicated website.

Not taking actions to mitigate the spread of the virus, leads to the phenomenon of “natural herd immunity” – i.e. in this case, where you allow a new virus to move through the immunologically naïve community and hope for the best.  Here, I’ll do some very rough sums to try to understand what this may mean for the US in the coming weeks; we’ll assume that no changes to the virus control strategy will be made, and that a vaccine (candidates of which are looking very promising), will not be available until at least the end of the year.

I’ll start some back of the envelope and calculations and commentate through them as we go.  Currently, there are 11,206,067 confirmed cases in the US with 247,229 deaths; this makes the apparent case-fatality rate (CFR) to be ~2.2%.  Interestingly, Singapore has done an amazing job with a CRF calculated to be ~0% (58,130 cases; 28 deaths)! In contrast, Yemen (which has low confirmed cases of COVID-19, 2,078) has a CFR of ~30%, and the situation in Mexico is very bleak with a CFR of ~10% and over 1 million confirmed COVID-19 cases.

Firstly, let us assume “natural” herd immunity is the goal by allowing the virus to move freely through the population.   There is no exact value. The assumption is that 70% of the population needs to be infected for herd immunity to be achieved.  Another assumption that needs to be made for this calculation is that the confirmed (reported) cases of COVID-19 represent a gross underestimation of “actual” infections.  Reputable publications suggest that the actual number of infections is between 3-24 times higher than that reported, with the number 6x appearing frequently and will be the one I use.  If we assume that actual COVID-19 cases are 6x higher than those reported, ~67 million people have been infected in the US, representing ~20% of the total (~328 million) population.  That approximates to the need for another ~160 million people that need to be infected for assumed “herd immunity”.   If we assume a CFR of 2.2% that will lead to an extra ~3 million deaths!  However, the actual CFR (assuming 6x underestimation of confirmed COVID-19 cases), is ~0.4 percent. Further, given improvements in management and treatment, an ~20% reduction in deaths has been observed in hospitalized people compared to the first wave of COVID in April.  This translated to approximately an extra 1 million deaths to achieve herd immunity.  In has to be noted that none of the assumptions  in these calculations take into account re-infections, and assume that COVID-19 survivors will be immune.  

Let’s now try to predict what will happen in the more near future, given the current situation in the US and the assumptions made above.  There are 43 left until December 31st, 2020 – exactly 1 year since the World Health Organization was informed of atypical pneumonia, which was confirmed within a week to be due to a novel coronavirus.   With some mitigation, which has already started (e.g. mandatory face masks in North Dakota), there is an expected decline, and here we are assuming a drop in average cases by 15,000 each week, for the next 6 weeks. Let’s assume there will be an extra ~2.6 million cases in the US by the end of the year, bringing the total confirmed cases to ~14 million (13,831,067).  Based on the assumptions made earlier this will equate to an extra ~46,000 deaths bringing the total to approximately 300,000 deaths (293,559).

Again, based on the assumptions already made, on Inauguration Day (January 20, 2021), in a “relatively good case scenario”, the administration will be looking at >14 million confirmed cases and >300,000 deaths.

Although not the top priority at the White House right now, “Operation Warp Speed”, was a great move with two mRNA-based vaccines from Pfizer and Moderna showing efficacies of 90% and 94.5%, respectively, in late phase III trials.  Hopefully, these can be approved and distributed sooner rather than later, rendering all the above calculations useless!  In the meantime, given the distractions, one of the more interesting things associated with the White House in recent weeks, is Ariana Grande’s new hit song “Positions”, which utilises the Grand building in the video; Ari could probably do a relatively decent job at controlling the virus right now.

Until next time … Tranquilo Polymaths.