A recent study estimated that, as of July 15, the mean overall population immunity to SARS-CoV-2 in the United States was 62 percent. The authors rightly concluded that "the U.S. population immunity against COVID-19 may still have been insufficient to contain the outbreaks and safely revert to prepandemic social behavior." The more important discovery here is that we're quite close to sufficient population immunity — and we will probably get there soon. By November, overall population immunity should exceed 85 percent, and if we do the right things, we should be able to finally end the misery of this pandemic.
The study stopped at July 15, which was the beginning of the fourth major COVID-19 wave in our country. Since then, we have had about 8 million more cases, the overwhelming majority of which have been in unvaccinated people. The wave is starting to crest, and assuming it follows the same pattern as other waves, we might guess that caseload could be back to minimal by November, with perhaps another 8 million cases. This would represent another 5 percent of the country, primarily the unvaccinated gaining natural immunity, and bring us to 67 percent. This increase, of course, sadly comes at the high cost of morbidity, mortality and hospital burden, with close to 2,000 people still dying every day.
Another thing that has happened since July 15 is the continued rise of those getting vaccinated. At the time of the 62 percent population immunity estimate, only 48 percent of the U.S. population was vaccinated. We are now at 54 percent, with 63 percent having received at least one dose. If only half of those who received only one dose proceed to full vaccination, that means another 10 percent of the population have been vaccinated since the July 15 estimate. So, adding all this to the unvaccinated gaining natural immunity from above brings us to 77 percent.
Of course, the biggest immunity gap is among children, with only an estimated 17.9 percent immunity level among those under 12 — and who currently have no access to vaccines. However, vaccines are coming soon for the 5 to 11-year-olds, very likely by November. With 30 million children ages 5 to 11, even if only 60 percent became newly vaccinated, that adds another 18 million vaccinated, or another 5 percent of the country, bringing us up to 82 percent. Of course, school vaccine mandates — for which there is strong historical precedent — could raise this even higher.
Speaking of mandates, school mandates are not the only mandates going into effect. Many hospitals have implemented employee vaccine mandates, and a number of other large private businesses have followed suit for their employees. The desire to create safe working environments is growing and is now supported at the federal government level by recent executive orders mandating vaccination for federal employees and contractors, as well as the Occupational Safety and Health Administration decision to require all companies with 100 or more employees to require vaccination or weekly testing.
Other slightly less heavy-handed approaches, such as fines levied by Delta Airlines against its unvaccinated employees, also seem to be working: Delta has already seen an increase in their vaccination rate from 74 percent to 78 percent. It seems reasonable to estimate that these vaccine mandates will add at least another 5 percent to population immunity in the next couple months, bringing us up to 87 percent.
Frustratingly, there are millions who cannot achieve immunity through vaccination, but the outlook is improving for them as well. With the Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) changes last month, immunocompromised people now have a third shot at successful vaccination, and there is growing evidence that those who fail even the third shot might benefit from a fourth shot, changes to their medications, or monoclonal antibody prophylaxis.
So, with a rampant wave of unvaccinated people getting COVID-19, increasing vaccination by choice and through protective mandates, vaccine availability for younger children, as well as improved protection for the immunocompromised — it seems that by November we could exceed 85 percent overall population immunity.
Will this be enough to stop this disease from wreaking havoc as it has been doing? Well, that depends entirely on us. If we let our impatience get the best of us and pretend it's over prematurely, we will likely see another wave, a variant even worse than Delta, or who knows what other biological punishments for our recklessness. But if we can just bear another two months or so of indoor mask-wearing in public, with vaccine/testing mandates for large gatherings, we can still live full lives this fall, and come winter this will be gone — hopefully. Wouldn't that be nice.
Dorry Segev, MD, Ph.D., is a professor of surgery at Johns Hopkins University School of Medicine and Professor of Epidemiology at Johns Hopkins Bloomberg School of Public Health. Segev has been leading an observational study of COVID-19 vaccine responses in immunosuppressed people since December 2020 and is the principal Investigator of the NIH/NIAID-funded interventional trial "COVID-19 Protection After Transplantation (CPAT)." Follow him on Twitter: @dorry_segev