As a physician, I want nothing more than to give my patients hopeful news. But as a scientist, I know that hope is not the basis for sound decision making. Nonetheless, today I’d like to be your hopeful scientist.
It has been a year since the coronavirus began to disrupt our way of life and economy, and take the lives of half a million of our colleagues, friends and loved ones. But could our winter of discontent now make for a glorious COVID-free summer? That might be exactly what the science is telling us.
Daily cases of COVID-19 in the United States, Florida and Tampa Bay have been on a nearly continuous decline since their peak in the second week of January. Nationwide, cases are down by more than 70 percent over the last seven weeks, and down 50 percent in just the past month. Daily hospitalizations and deaths are also dropping rapidly.
Since we can’t yet ascribe these trends to vaccinations, various theories have been proffered to account for this decline in disease activity. Some health experts speculate that the winter surge resulted in increased face mask use and social distancing coupled with reduced mobility. Others theorize we are seeing the normal seasonality of coronavirus infections. While neither of these theories seems fully plausible, a growing number of experts discreetly theorize that we are approaching herd immunity. I say “discreetly” because this virus has repeatedly embarrassed infectious disease experts and epidemiologists such that scientists have become quite gun-shy about COVID-19 predictions.
Given that approximately 70 percent or more of the population must be immune to approach herd immunity, how is it possible to make such an argument when only 9 percent of the U.S. and Florida populations have had documented COVID-19 infections and only 15 percent have received at least one vaccine dose?
One possible answer to this pandemic paradox is that there are far more undocumented than documented cases. Recall that most COVID-19 cases are either mildly or entirely asymptomatic and easily missed. Estimates of undocumented cases range from four to 10 times the number of documented ones with best estimates suggesting a six-fold excess. The lack of large-scale serological surveys to detect antibody-mediated immunity has complicated such estimates, as has our inability to easily measure T cell immunity, a critical aspect of anti-viral protection.
However, assuming the six-fold estimate is correct, more than 50 percent of Americans and Floridians already have partial or full immunity from infection, while another 15 percent of Americans and Floridians have achieved partial or complete immunity from their vaccinations. This means we could already be approaching full or partial immunity in at least 60 percent of the population.
Now being a scientist, I must point out certain caveats. First, spread of the far more infectious UK variant of the virus could outpace vaccinations or, worse, the South African variant, which is marginally resistant to vaccination, could proliferate. Second, the population could grow complacent in wearing face masks and social distancing, which will help spread these variants. Third, the vaccines’ efficacy may prove more short-lived than expected. Finally, the estimates of undocumented immunity that I mentioned earlier could be exaggerated.
The good news is that we can test this hypothesis. If we continue to see a steady decline in new cases over the next two months, the hypothesis is likely correct and America may seem very different come June. On the other hand, an uptick in cases will indicate we will have to wait another five months until about 60 percent of the population is fully immunized to reach herd immunity — sometime in August.
Even in this worst-case scenario, the recent approval of the Janssen (J&J) vaccine, which is more easily stored and requires only one dose, will help. Moreover, the Biden administration could accelerate our march to herd immunity by recommending that those with prior COVID-19 infections receive only one dose of the other vaccine options, still providing robust immunity.
So how does this all end — likely with a whimper not a bang. New cases will fade out this summer with occasional flares that can be effectively contained with contact tracing and quarantining. Re-infections will occur but be mild. For the next few years, we will likely require annual booster COVID vaccinations designed to prevent the latest, most severe, and most prevalent variants along with our annual influenza vaccine. Ultimately, I expect benign variants of SARS-CoV-2 to join their coronavirus cousins that account for a quarter of common colds.
Until then, the physician in me wants you to know there is hope. And the scientist in me warns that each one of us can still influence pandemic outcomes with our choices and behavior. Therefore, it is critical we continue to wear face masks and maintain social distancing protocols until public health officials give us the “all clear” — hopefully in a few months.
Dr. Charles Lockwood is the senior vice president of USF Health and dean of the Morsani College of Medicine.