(PHOTO: AP Photo/LM Otero)
SALT LAKE CITY – Herd immunity happens when a large percentage of people develop immunity to a disease either through vaccination or infection.
Dr. Shankar Swaminathan, the Chief of the Infectious Disease Division at University of Utah Health, asks people to imagine that a person with COVID-19 typically infects two people.
“Let’s say that half the people are immunized. So, now, if you have it and you run into two people, on average you’re going to infect one person instead of two,” Swaminathan says.
Although approval of a COVID-19 vaccine may be just around the corner, it’s unclear how many people would need a shot to achieve herd immunity in Utah.
However, Dr. Swaminathan says the more people who are immunized, the greater the chances of achieving herd immunity.
“Let’s say two out of three people get vaccinated. Now…you’re able to spread it to less than one person,” Swaminathan says. “On average, the disease is going to start dying out.”
The best guesses range anywhere from 70% to above 90% immunity to get to herd immunity.
Dr. Tamara Sheffield, the Medical Director of Community Health and Prevention at Intermountain Healthcare, says people who have recovered from COVID-19 do have immunity to it.
“Those who have the severest disease tend to also have the greatest amount of immune protection. But we don’t know how long that will last,” Sheffield says.
Those are some of the reasons she asks people not to try and catch COVID-19. She also reminds people that they cannot know for sure how their bodies will react to the virus.
Dr. Mark Oliver, the Head of Infectious Disease at St, Mark’s Hospital in Salt Lake City, agrees with following public health guidelines.
However, he also believes the immunity COVID-19 patients acquire will play a role in achieving herd immunity.
“We are encouraged that a combination of vaccination plus ongoing infection in the community will get us to that magic percentage that we call herd immunity,” Oliver says.
Especially because we do not know enough about the vaccine yet.
“We really won’t know for a year or more if the vaccine gives better protection than native infection. Also, how long lasting the immune response will be from the vaccine is still a big question mark. Is this a vaccine [where] you’re going to get two shots and be protected with 95% certainty for the rest of your life? Or is this a vaccine that we’re going to have to get another booster at six months or a year or two years?” Oliver says.
But Dr. Oliver also says if a vaccine is safe and effective, getting one will help protect people who cannot take it for health or other reasons.
Dr. Sheffield says vaccines also tend to be more effective than any acquired immunity.
“Vaccines…tend to provide a fairly consistent level [of immunity], and sometimes a higher level, than having had a disease or being exposed to a disease. We will also, though, have to watch over time to see how long that protection lasts,” Sheffield says.
COVID-19 coronaviruses transmitted from person to person. It is a virus that is similar to the common cold and the flu. So, to prevent it from spreading:
Utah’s Coronavirus Information
The Church of Jesus Christ of Latter-day Saints
Utah Coronavirus Information Line – 1-800-456-7707
Centers for Disease Control and Prevention
Commonly asked questions, World Health Organization