Dr. Anthony Fauci, our most trusted health communicator for good reason, was right when he told a beleaguered nation more than a year ago that “the showstopper will ultimately be a vaccine.” It is, and will be, but only if we vaccinate most of the population.
What Dr. Fauci said to the New York Times this week, in a front-page article with the grim headline “Herd Immunity’ Dims with Pace of Vaccinations” (online it was an even grimmer “Reaching ‘Herd Immunity’ Is Unlikely in the U.S., Experts Now Believe”) was more nuanced, perhaps too nuanced.
“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,” he said. “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.” That makes perfect sense. But perhaps we should think twice before abandoning the idea of “herd immunity.” The idea has served the public health community well for almost a century.
And we have all heard about the importance of reaching it. We know that vaccinating a large part of the population against SARS-CoV-2 can reduce exposure even for people who remain unvaccinated, which is after all the main point of herd immunity.
That term was originally used by American veterinarians concerned with protecting livestock, and first applied to humans in a 1924 article in The Lancet. Back then, public health researchers used the term to explain when the percentage of people with immunity was sufficiently high to confer protection on the rest of the population (that is, the “herd”). Resistance to infection could be conferred either from a previous exposure or from immunization.
The term has been fraught with misinterpretation ever since, not the least because the percentage of people who need to be protected against a disease to achieve “herd immunity” varies substantially for different diseases, usually depending on how easily the disease can spread person-to-person. For example, measles, a nasty and highly contagious childhood disease once thought eliminated in America, requires that more than 90 percent of a community be immunized.
While we may not know precisely the level of vaccination coverage that would confer herd immunity for SARS-CoV-2, the virus that causes COVID-19, it could exceed 80 percent. Even if so-called herd immunity is achieved, there is never full protection against disease. We will need to live with this virus, yet suppress its infectivity and reduce exposures from people “outside the herd” that put non-immunized people at risk. That is why public health experts expressed deep concerns with clusters of measles among unvaccinated communities, such as religious communities.
The former director of CDC’s Immunization Program, Dr. Walt Orenstein, explained that the goal of a vaccination campaign is to achieve “community protection,” a term he found interchangeable with “herd immunity.” In short, it is a civic goal, a public good.
By analogy, we aspire to achieve community protection against fires based on the number of firefighters and equipment needed to protect a given population and geographic area. We need to think of uptake of accessible, safe and effective vaccines as the proven way to prevent the population from attack by this infectious disease.
Just as we are making tremendous gains against COVID-19, we find ourselves fighting a second epidemic—vaccine misinformation spread by political ideologues, science doubters, and a sophisticated “anti-vaxx” movement. These distractions are keeping us from reaching our goal of a protected community.
Surveys we have been conducting over the last year at CUNY School of Public Health since March of 2020 suggest that while a hard core of outright opposition remains in place, the number of people willing to accept a vaccine is steadily rising in the United States. Reaching our goal of high vaccine coverage, however, is being delayed not only by a small minority who flatly reject vaccines but also by a large number of women and men who just want to “wait and see”. Overall, when we combine both outright vaccine deniers and those who want to “wait and see,” we fall below an 80 percent herd immunity threshold.
The nation seems to split into have a few camps:
- Science-based zealots who believe we need to get to herd immunity
- Realists who think herd immunity will be hard, if not impossible, to achieve
- “Wait and see people,” now termed vaccine hesitant
- Science deniers—skeptics and refusers, people who insist, half a million deaths later, that COVID-19 is less dangerous than vaccinating against it.
We need to follow the science and evidence. Over 90 percent are not in the denier camp.
If fence-sitters climb down and get their shots we can get to community protection. These people are hesitant, not militant; they are mostly caring citizens, many of whom consistently vaccinate themselves against the flu and their children against childhood diseases. They do not differ greatly from people who have already been vaccinated. Effective messages, messengers, incentives, and media can reach them. We need to spend more resources finding these levers and less time sweating over epidemiological details. An ever-present anti-vaccine movement thrives on social media platforms by challenging the very reality of Covid-19 and the need for vaccines that prevent it. We can’t let this stand, and we can’t afford mixed messaging. however well intentioned, that aids their destructive work.
Herd immunity has aspirational value to us all. We need a well-informed leadership and a populace that does not give in to COVID-19. The vaccine can still be the showstopper Fauci said it was 13 months ago. Herd immunity is a goal we can achieve this year if we have the will to do so. Our concern about headlines like in Monday’s New York Times is that they take our eyes off the prize. The only goal that matters is to stem COVID-19, stay safe, and return to the ordinary lives we yearn for. We’ve got to roll up our sleeves, get the jab, and get the job done before it is too late.