Herd immunity isn’t the right goal. Here are the right metrics.
Earlier this month, Texas Gov. Greg Abbott declared “mission accomplished” with Covid-19 — announcing that Texas would fully reopen “EVERYTHING” and lift its mask mandate. The decision was quickly criticized by experts and public officials, with President Joe Biden describing the move as “Neanderthal thinking.”
At the same time, America’s coronavirus outbreak is truly improving. Cases, hospitalizations, and deaths are down, and vaccination rates are up. So maybe it’s not that unreasonable to ask: When will this be over? When can we get back to normal — and when should states reopen to help make that happen?
Experts told me there’s still a lot of guesswork involved, and we might not know when we’re truly back to normal until we get there. “I reckon that point will become apparent in retrospect,” Bill Hanage, an epidemiologist at Harvard, told me. “We will suddenly realize that we are laughing, indoors, with people we don’t know and whose vaccine status is unknown, and we will think, ‘Wow, this would have been unimaginable back when. …’”
But there are metrics to judge whether a state should reopen — most of which we’ve heard about since the start of the pandemic: cases, hospitalizations, deaths, and vaccination rates.
The goal is to get these metrics to safer levels, and make sure those favorable trends continue. So the number of cases, hospitalizations, and deaths should drop — preferably to lower points than they were before the fall/winter surge — and, just as crucially, keep falling from there. Meanwhile, vaccination rates should consistently trend up.
One metric not worth chasing for now: herd immunity. In theory, it’s a sensible goal — the point at which so many people have natural or vaccine-induced immunity that the virus’s spread slows and eventually stops. The problem is we don’t know the proper threshold for herd immunity; there are too many unknowns about the virus, its variants, and how immunity works to say for certain.
As Anthony Fauci, the top federal infectious disease expert, said at a press conference this week, “We should not get so fixated on this elusive number of herd immunity. We should just be concerned about getting as many people vaccinated as quickly as we possibly can, because herd immunity is still somewhat of an elusive number.”
The process of reopening should be done slowly. By reopening bit by bit, each state can see if any of its moves are leading to too much spread of the virus. If things go awry, a state can pull back. If things go fine, maybe it can keep lifting restrictions.
All of this should also be tracked locally, as different cities or counties can have different experiences than a state as a whole.
By all of these standards, much of the US is moving far too quickly. The country’s coronavirus case, hospitalization, and death numbers are too high — still higher than they were before the fall/winter surge — and the vaccination rate is too low, with a measly 12 percent of the country fully vaccinated. Texas, despite its rush to reopen, is not better off on Covid-19 cases, hospitalizations, and deaths or vaccines.
That could lead to new surges before the vaccine campaign is really done. It’s especially concerning because of other possible threats the country faces with Covid-19 — particularly the potential rise of new variants, which could shape-shift to evade immunity, rendering our efforts so far fruitless. Experts say the best way to prevent that from happening is to contain the virus, denying it the replications it needs to mutate.
The US is almost at the finish line: As Biden has said, every adult in the country could be vaccinated by June. But until then, it’s on us, and our public officials, to make sure as many of us make it to that finish line as possible.
For more on how states can get back to normal, read my explainer at Vox.
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