Monday brings with it a fairly depressing story from the New York Times about how infectious disease experts are saying that herd immunity is no longer the goal for the U.S., and is likely unrealistic given slowing vaccination rates.
"People were getting confused and thinking you’re never going to get the infections down until you reach this mystical level of herd immunity, whatever that number is," says Dr. Anthony Fauci, speaking to the Times. "That’s why we stopped using herd immunity in the classic sense. I’m saying: Forget that for a second. You vaccinate enough people, the infections are going to go down."
Without herd immunity at a national level — which may be impossible given the return of global travel, and the spread of variants from abroad — we are going to face an ongoing threat of COVID infection that may come in season waves. And with vaccine hesitancy unnervingly high in multiple states — including Mississippi, Tennessee, North Dakota, Wyoming, and even parts of Georgia and Ohio — we are bound to see outbreaks for years to come wherever vaccination rates are low.
But the herd immunity calculus has changed, experts are saying, especially with the highly infectious U.K. variant, B.1.1.7, now the dominant strain in the U.S. Experts revised the presumed threshold of herd immunity from 60 or 70% vaccinated up to "at least" 80%. And between the vaccine hesitant, currently estimated to be around 30% of the adult population, and children under 12 for whom no vaccine is likely to be available this year, it's going to be even more difficult to reach the threshold, whatever it may be.
High vaccination rates in the Bay Area and across much of California could mean we'll have a kind of localized herd immunity, for a time. But we still don't know if booster shots will be needed by the end of the year, and we still can't say that a variant won't take hold that is capable of making vaccinated people very sick and even die.
New York Magazine has a slightly more optimistic piece today, after speaking to some experts, which still discusses herd immunity as being possible. But there, we have experts warning that we are likely to continue to see tens of thousands of deaths across the country for weeks or months to come.
One infected superspreader could spur an entire regional wave somewhere, the way a single woman in South Korea is believed to have impacted that country's pandemic trajectory.
"We’re beyond the hump, but if it’s a perfectly symmetric curve, we’re going to see as many people infected and die on the downside as you did on the upside,” says Justin Lessler, infectious-disease epidemiologist at Johns Hopkins, speaking to New York Magazine. “If we flatten the curve more slowly, we could see hundreds of thousands more deaths. If we accelerate the process, then we don’t have to see those deaths."
Keeping an eye on hospitalization numbers will be key for public health experts in determining whether variants are causing more serious breakthrough infections, especially in places with high rates of vaccinations.
So, perhaps what we're hoping for is virus rates dipping so low in the Bay Area that life looks pretty normal here, but the further afield one travels, the more uncertainty there should be about how many around you are actually fully vaccinated. And meanwhile we will watch spikes happen in other parts of the country, and waves of new death, and maybe some of those will result in more people being convinced to get their shots.
Photo: Joshua Hoehne