Names are hard

by JANA ZAHLAN

In the early days of the COVID-19 pandemic, the phrase “herd immunity” spread rapidly and highlighted America’s hope for a quick end to the emerging event.

According to the World Health Organization (WHO), herd immunity is “the indirect protection from an infectious disease that happens when a population is immune either through vaccination or immunity developed through previous infection.”

While many people have been either infected, vaccinated, or both, this does not provide the same protection from COVID-19 that it might from other infectious diseases. Experts recommend taking additional steps, rather than depending on herd immunity, to stay safe from the harmful effects of COVID-19.

Dr. Luca Giurgea, a physician scientist at the National Institutes of Health (NIH) and National Institute of Allergy and Infectious Diseases (NIAID), discussed the concept of herd immunity with the AmNews: “With COVID, there’s a few assumptions that need to hold true for this herd immunity concept to work out …. I don’t really like applying the herd immunity concept to COVID … because I think, particularly in the general population, [it] comes with certain expectations that will disappointingly not be met.”

While herd immunity has successfully protected populations from other infectious diseases, such as measles and smallpox, all efforts to stop the SARS-CoV-2 virus — the virus behind COVID-19 — from spreading have fallen short. According to Giurgea, immune responses against this virus, whether achieved through vaccination or a previous infection, subside with time. Additionally, the ability of the virus to mutate allows it to evade these immune responses and continue to spread in the population.

(At the full link is an embedded list of long covid symptoms if you'd like to browse them)

Despite the efforts of public health officials to relay this information to the public, myths and misconceptions about COVID-19 herd immunity continue to influence opinions and decisions about protective measures, such as social distancing, masking, and vaccinations. To better understand the reason behind these misconceptions, the AmNews spoke with Dr. Lauren Ancel Meyers, an epidemic computational epidemiologist and professor at the University of Texas at Austin.

Asked about belief in herd immunity as a reason to abandon COVID-19 protective measures, Ancel Myers said there is a “misunderstanding of what herd immunity is … The technical meaning of herd immunity means … a large fraction [of the population] have gotten it. [That there is] a lot of immunity in the population, so it’s going to stop spreading [until] we’re done with it, and clearly, we are not in that universe at all.”

Ancel Myers said there may be a need for a new term that captures the change in perceived COVID-19 risk over the course of the pandemic and reduces confusion about the concept of herd immunity.

“We do have more immunity in the population because people have gotten infected, because people have gotten vaccinated now multiple times … and that has, indeed, made the virus less severe … but it’s not stopping it from spreading, so we don’t have herd immunity,” Ancel Myers said. “… the threat is different than it was early on, and that is in part because of immunity.”

Echoing this notion, Giurgea emphasized the benefits of keeping up with yearly vaccine boosters. Research has demonstrated the role of vaccines in reducing the number of hospitalizations, deaths, and Intensive Care Unit admissions after COVID-19 infection in vulnerable patient populations. COVID-19 vaccines also have been shown to protect infected individuals from long-term health problems, generally referred to as Long Covid.

Immunity does not have to be perfect to be beneficial. “Even though we might not get to the point of eradicating COVID altogether … the more immunity we have in the population … the slower the virus is going to spread and the less likely any one of us is to get infected or end up in the hospital,” Ancel Myers said. “Even if we can’t achieve … this aspirational target of reaching herd immunity, there is still a huge amount of public health benefit to increasing immunity in the population through vaccination.”