Does Herd Immunity Still Matter?

Experts have maintained that vaccinations are the key to fighting against COVID-19, but they may have different expectations of what the end of the pandemic will look like.

In the early days of the vaccine rollout, health authorities supported achieving “herd immunity,” or community immunity, a situation where a substantial portion of the population is immune to an infectious disease through vaccination or prior illness.

Some doctors remain optimistic that high vaccination rates can eliminate the virus, but others say we may have to settle for an “endemic” state of COVID-19, referring to the constant presence of the virus. This could look similar to that of the seasonal fu, where people need annual or incremental vaccinations to stay safe from the virus

Anthony Harris, MD, MPH, associate medical director at WorkCare, says that an endemic endgame is more likely than herd immunity due to the inability of current vaccines to fully prevent transmission and the large numbers of unvaccinated people.

“We're looking to head towards a scenario in which we experience COVID much like we experience the seasonal flu,” Harris tells Verywell. “That's the future we're hoping for—not that COVID will ever go away, but that it will become a minor illness compared to the pandemic that we're seeing, in regards to morbidity.”

While the flu can result in severe hospitalizations or deaths, most flu cases are mild. What’s more, we’ve learned to live with seasonal flu—without shutdowns.

Shruti Gohil, MD, associate medical director of epidemiology and infection prevention at UCI Health, says that it may be too soon to predict the future of the pandemic. Regardless, the U.S. still needs to boost vaccination rates, she adds. 

“We're asking the wrong question about striving for herd immunity,” Gohil tells Verywell. “Rather, we should be asking the question: ‘Why aren't we getting vaccinated?’” 

Herd Immunity Is Impossible Without Vaccination

The COVID-19 vaccines, like all vaccines, have never been 100% effective at preventing transmission. Vaccine efficacy also wanes overtime. A recent study of the Pfizer vaccine showed that its effectiveness against transmission dropped from 88% to 47% five months after vaccination.

People who are fully vaccinated against COVID-19 can be vulnerable to breakthrough cases and transmit the virus to others, according to the Centers for Disease Control and Prevention (CDC). However, breakthrough cases tend to be less severe than cases among unvaccinated individuals.

This “inability to prevent transmissions” among fully vaccinated people will make herd immunity nearly unattainable, even with vaccine boosters, Harris says. While boosters increase an individual’s protection from the virus, it is unclear whether boosters can curb virus transmission, he adds.

“The main reason that we're preaching vaccination is not again to prevent transmission but to prevent hospitalization and severe illness,” Harris says. 

Vaccine hesitancy remains a clear roadblock to reaching herd immunity, Gohil says. 

“The whole game is about the race between how fast any given virus mutates, how fast it spreads, and whether or not we have enough ‘soldiers’ [antibodies] at the ready in our systems,” Gohil says.

Currenlty, 56% of the U.S. population has been fully vaccinated against COVID-19 and 65% has received at least one shot. Nearly all of COVID-19 deaths this summer were among unvaccinated individuals, the Associated Press reported.

A fully vaccinated rate of greater than 75% among the entire U.S. population could be a healthy goal, Harris says, though virus mutations may call for a higher threshold. 

What Should We Strive For?

We should still fight to get as many people vaccinated as possible, whether that means reaching an endemic or herd immunity, Gohil says.

“Striving for herd immunity should still be a goal,” she adds. “We should strive for it, and I do think it's achievable.”

Even if herd immunity isn't within reach, both Gohil and Harris agree that a more robust proportion of vaccinated people could still prevent future variants and new strains, turning the current pandemic into a more manageable situation. 

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.