Hospitals Can Achieve Herd Immunity Even If the U.S. Can’t

One question that doesn’t seem to come up in discussions about how best to reach herd immunity against COVID-19 is this: How big is the herd? Medical experts and policy makers talk about achieving herd immunity country by country. But investigators with Narayana Health in Bengaluru, India, suggest that the herd could be as small as the health care workers at a particular health care institution. In their preprint study in the American Journal of Infection Control they write that “health care facilities should aim for a very high fully immunized workforce to create a local environment where herd immunity comes into play and prevents transmission to patients admitted for non-COVID ailments. As non-COVID clinical workload increases, [the] higher the number of immunized HCWs [health care workers], the less the theoretical risk of transmission to the patients.”

The Centers for Disease Control and Prevention (CDC) has said at different times during the pandemic that anywhere from 70% to 85% of the population would have to be vaccinated to reach national herd immunity. But with only 58.5% of Americans having gotten both doses of a vaccine, the CDC recently is shying away from a fixed goal for vaccinations.

Jefferson Jones, MD, MPH, a medical officer on the CDC’s Epidemiology Task Force, last week said that meeting a specific target could be “very complicated.” Jones added, according to the Los Angeles Times, that “thinking that we’ll be able to achieve some kind of threshold where there’ll be no more transmission of infections may not be possible.”

The investigators at Narayana Health reached their conclusions by surveying 14,837 health care workers in 20 hospitals. The HCWs included doctors, nurses, and paramedics, and the number of HCWs in specific health care facilities ranged from 69 to 4499 and was about a 50/50 split between females and males. The overall uptake of the vaccine was 90% (13,355).

“The uptake of vaccination was highest among senior doctors with only 37 (2.9%) of the senior doctors not getting vaccinated,” the study states. “The lack of uptake was 1273 (11.4%) among the nursing and paramedical staff, 141 (7.5%) among junior doctors and trainees 35 (5.5%) among the administrative staff.”

The researchers note that buy-in, or lack of it, among HCWs regarding getting the COVID-19 vaccine has been a major concern. The reasons for hesitancy among HCWs mirror those among the public who are vaccine hesitant: fear of side effects, not being convinced that the vaccines are safe or that they work, concern among pregnant or breastfeeding woman about how the vaccine might affect their child, religious beliefs, conspiracy theories, and misinformation.

Administrators at Narayana Health employed several strategies to clear these hurdles and get as many HCWs vaccinated as possible. They found role models. First in line to get vaccinated were senior physicians, and health care facilities administrators.

They also relied on the adage that when it comes to battling vaccine hesitancy, a picture might be worth a thousand words.

“Photo booths were erected where everyone getting vaccinated was encouraged to take themselves photographed and use it as their display profile in different social media platforms,” the study states. “This seemed to reassure the other HCWs and may have played an important role in the high uptake seen in all these institutions.”

Fear also may have played a role.

“The infection rate in the un-immunized health care workers was significantly higher compared to those who had been completely immunized,” the study states. “This should be an important impetus for HCWs as well as the general population to get vaccinated. It has also been shown that the viral load in vaccinated patients is much lower compared to those who are not vaccinated. This is of paramount importance because the viral load has been identified as a key driver of transmission.”