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Experts say achieving herd immunity to COVID-19 will be a step-by-step process that will rely heavily on how many people get vaccinated. Luis Alvarez/Getty Images
  • While the rollout of COVID-19 vaccines is encouraging, a small percentage of Americans have been vaccinated so far.
  • Most models predict that a majority – 60 or 70 percent – of people in a population need to be vaccinated to achieve herd immunity.
  • Herd immunity without vaccinations is possible, but it would cause millions of people to die as well as overwhelm the healthcare system.
  • The path to normalcy will be gradual, but positive results will start to be seen as more people are vaccinated.

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.

If 2020 was the year that COVID-19 disrupted life as we know it, 2021 promises to be the year that vaccines start to bring things back to normal.

But there’s still a long way to go. As of January, more than 17 million vaccinations have been given worldwide, with more than 6 million of those administered in the United States.

The U.S. figures represent less than 2 percent of the country’s population, so that begs the question of when we’ll start to round the corner.

Ask any expert in infectious disease and they’ll tell you that halting the spread of disease comes down to one big factor: herd immunity.

“Herd immunity works because so many people ‘in the herd’ are immune to a disease that they act like a buffer for those in the same community that aren’t immune and protect them,” explained Dr. Shelley Facente, an infectious disease epidemiologist and founder of Facente Consulting, a public health consulting firm dedicated to under-resourced communities.

“For it to work, you really need a lot of immune people,” she told Healthline. “Twenty or 30 percent of people in a community being immune isn’t enough to protect those who are vulnerable. Given what we know about how easily COVID-19 spreads, most scientists estimate that between 60 and 70 percent of the entire community would have to be immune before we’d have herd immunity.”

Even without a vaccine, COVID-19 would run its course and herd immunity would be achieved through mass infection.

But this would come at a deadly cost.

Dr. Casey Kelley, a physician who founded Case Integrative Health and has spoken at length about the virus, told Healthline that some groups have proposed simply letting the virus run its course.

“The problem with this idea is, of course, that the majority of the population would need to contract COVID-19,” she explained. “The strain on the health system would undoubtedly risk thousands, if not millions, of lives.”

This is why vaccines are important.

Kelley says that they’re meant to help the body develop antibodies that can attack the virus.

She said that this should confer some, or all, of the benefits of natural immunity without having to actually contract the virus.

Vaccines give us reason to be optimistic about the coming months.

But as case numbers continue to skyrocket, experts say it’s important to be vigilant.

Dr. Philip Smith, a public health expert and assistant professor at Miami University in Ohio, served on the university’s Safe Return to Campus Planning and Coordinating Committee.

He told Healthline that the pandemic has been a learning experience for those who work in the health field.

“We have learned so much from this past semester about what works and what needs improvement,” Smith said.

“We know we can create safe environments,” he added. “We have observed from the last semester that the risk of transmission is very low when all individuals in a setting are wearing masks and keeping distance – like in a classroom or office space – and when cases and contacts are quickly identified, then isolated or quarantined. We have also observed that COVID-19 can spread like wildfire when individuals do not take precautions, especially at social gatherings.”

Until herd immunity starts to take root, Smith said it’s crucial that institutions mandate mask and distancing policies, along with robust testing and contact tracing programs.

High risk individuals should stay home and be given options to engage remotely.

The past two decades have seen an upswing in the number of people who are skeptical of vaccines, if not opposed to them entirely.

COVID-19 vaccines are new and came together quickly, which can lead to some degree of skepticism.

For those who have questions, experts say the best person to talk to is a trained medical professional, such as a family doctor.

Dr. William W. Li, author of “Eat To Beat Disease: The New Science of How Your Body Can Heal Itself,” broke down what he tells his patients.

“As a physician, I always try to explain the need for medical treatments to my patients. If they are skeptical, giving them confidence in the treatment and understanding it can convince people to go forward with it,” he told Healthline. “I sometimes will ask if someone has a friend or family member who has gotten the vaccine to help them feel like they are not the only ones getting it. Finally, I have photos of the damaged lungs of people who have been infected by COVID-19 and, just like the anti-smoking ads, the reality of the disease can sometimes help people make up their mind.”

Experts say COVID-19 vaccines may be new, but it’s important to remember that the science behind vaccines, and what makes them work, is ironclad.

Smith says that there are some unknowns surrounding whether COVID-19 can be eradicated or merely contained, but he points out that we’ve seen in the past what an effective vaccine can accomplish.

“There is a common ingredient in every single example of eradication in our history: herd immunity resulting from widespread vaccination,” he said. “The extent to which we can return to normal will hinge completely on the extent to which people are willing to be vaccinated, and on the ability of nations to fairly and efficiently distribute the vaccine on a global scale. When anti-vaxxer sentiment and lack of vigilance impede herd immunity, disease incidence very predictably increases.”

Nearly a year into the pandemic, it would be comforting to know there’s a certain date that things will return to a more normal setting.

It’s impossible to pin down such a date, but with the rollout of vaccines, we’re gradually getting closer to that time, whenever it may be.

Kelley says we’ll need to see a large percentage of the population vaccinated before we start to round the corner. One metric to watch out for, she says, is R0 or R-naught.

“An R0 of 2 means that one infected person will pass COVID-19 to two other people,” she explained. “There are lots of factors that go into this number, but basically an R0 greater than 1 means the virus is growing, an R0 of 1 means the virus is stable, and an R0 less than 1 means the virus is fading. As more people get the vaccine in a region, R0 for that region should start to fall dramatically.”

Smith says it’s important to be patient with what’s going to be a step-by-step and not an instantaneous process.

“Returning to normal is not going to be an experience like one day we’re in COVID-19-land, the next day things are the way they were before things started. The return to normalcy is going to be an inch-by-inch process where we gradually become more and more normal over time,” he said.

“The meter for normalcy is going to be herd immunity, but not just of our own communities and our own nations,” he added. “Our herd immunity is going to need to be global because we live in a global society. This is going to take a long, long time. With this said, as more people get vaccinated, the more we move the meter, and the more we can gradually move back to normal.”