In anger, on Thanksgiving Day, I wrote: “A month ago, 1,000 people a day were dying in this country of COVID-19, and that came to feel routine; now, it is 2,000, but wasn’t it higher in the spring? By the end of December, look for it to be three or four.” According to the NYT, yesterday, the number of COVID-19 deaths in the US was 4,406 (and we’ve been averaging 3,000+ COVID deaths per day in recent weeks). That is an awful human tragedy. Given that the IFR for COVID-19 seems to be roughly 0.5% – meaning that 1 in 200 infected individuals dies from the disease – it also suggests that nearly a million people a day were likely being infected with SARS-CoV-2 between Thanksgiving and Christmas in the US. So much for all that holiday travel.
On December 17th, I predicted that roughly 2/3 of the US population would enjoy some form of immunity (either via infection or vaccination) by February or March, and that the pandemic was likely to be effectively over in the US by March or April. I’d planned to revisit those predictions today in some detail, but as it turns out, my math is all coming out about the same as it did a month ago, with the caveat that it now looks extremely unlikely that the US will successfully vaccinate 100MM people by the end of February; however – given that, in recent days, the US has been vaccinating half a million+ people a dayx (perhaps even closer to a million on certain days, though lags in reporting and differences across publicly-available trackers make it a little hard to say with confidence), and that that number will likely cross a million per day in the coming weeks, and perhaps two million per day by sometime in February – I think it is likely that the US vaccinates 100MM+ people by the end of March.
Meanwhile, this very dense research paper published last week in Science concludes: “[O]ur data show immune memory in at least three immunological compartments was measurable in ~95% of subjects 5 to 8 months PSO, indicating that durable immunity against secondary COVID-19 disease is a possibility in most individuals.” Basically, the vast majority of people who become infected with SARS-CoV-2 experience some form of lasting immunity (and, as is noted elsewhere in the paper, symptomatic reinfection is extremely rare).
With that in mind – even accounting for the small fraction of people who do not enjoy immunity after infection, and the fact that many vaccinated people will have previously been infected – the 100MM+ people who have already been infected with SARS-CoV-2 in the US today (and, even more, the ~130MM+ people who will likely have been infected by the end of March) gets us to the “roughly 2/3 of the US population would enjoy some form of immunity” by the spring mentioned above. The herd immunity threshold for COVID-19 remains unknown, but it is probably somewhere between 70% and 90%; however, given that many of us will continue masking and taking other precautions, a lower percentage will likely suffice to break epidemic transmission; thereafter, I think we can expect scattered outbreaks through the spring (a la the 2014-2015 Disney measles situation brought to us by rich, Disney-loving anti-vaxxers), but no further explosive community spread until full herd immunity is reached.
Between immunity from vaccination and immunity from infection, the pandemic will likely be largely over in the United States by the spring. In hard hit places like New York City (where something like 30-40% of the population probably already has immunity via infection), we may reach the end of the pandemic still sooner if our elected officials can just get their shit together and run a vaccination campaign. These are real reasons for hope, as well as for appreciation for the people, like my friend Naman, who are out there making sure that vaccinations happen.
Postscript: Although there’s always the more infectious variant to worry about…