‘It’s definitely progress’: Vaccines lead way to herd immunity, possibly by this summer

Health experts: Increased vaccine supply will speed things along

MADISON, Wis. – Herd immunity can be likened to the light at the end of the tunnel of the coronavirus pandemic, with vaccinations leading the way.

“Herd immunity is the concept that as more people are immune to a particular infectious disease, the virus or organism has a dead end, meaning that the herd is protected,” said Dr. Matt Anderson, senior medical director for primary care at UW Health. “It’s the reason we don’t have things like measles and polio, because even if one individual isn’t vaccinated, the herd is. There’s just not as much infectious organisms to go around.”

Herd immunity can be built through illness or vaccination.

“I do think, ultimately, it’s going to be largely through vaccination,” Anderson said.

At the beginning of the pandemic, some floated the idea of building herd immunity by letting everyone get infected.

“That, really from the standpoint of protecting vulnerable patients and protecting our health systems, did not prove to be a good methodology,” said Dr. Alison Schwartz, the associate medical director of infectious diseases at SSM Health St. Mary’s.

Experts estimate herd immunity against COVID-19 to start at 70% or higher. They can only approximate how many people have built immunity after unknowingly getting COVID, but can use that in combination with those who have tested positive along with those who have been vaccinated to estimate the total number of people in the country who are immune. It’s also unknown how long immunity might last.

Schwartz said her best guess at how many people have immunity in the country would be about 45- 50%.

“So, still not there yet,” Schwartz said. “It’s definitely progress. Certainly, when you think about looking at 28 million people who have been infected, and then how quickly, essentially between December and now, we’ve already been able to get to 65 million vaccines.”

More vaccine would speed up timeline

So far, the biggest challenge to vaccinating has been a lack of supply. On Tuesday, Wisconsin health officials announced the state would receive substantially more doses in the coming weeks. That’s as vaccine makers tell Congress that supplies across the state will soon surge.

“As the vaccine supply continues to increase, we’re hoping to see those numbers go up really quickly,” Schwartz said. “(The goal is) really seeing vaccines as the way out of this, to really get the numbers up to have enough people immune where we reach the threshold to stop the virus replication and reach some sense of normalcy.”

Many factors go into when herd immunity will be reached, including how virus variants play out.

“I do see some optimism toward the summer,” Schwartz said, adding that it likely wouldn’t happen by the spring.

“Unfortunately, I don’t think it’s any time real soon,” Anderson said. He also doesn’t expect herd immunity before the summer. “I think when you look at where we’re at now, the ultimate question about herd immunity is how many choose to take the vaccine.”

Masking, distancing also create ‘dead-ends’ for virus

On top of choosing to get the vaccine when they’re eligible, Anderson said people can also help by continuing public health measures such as mask-wearing and physical distancing.

“The more dead ends the virus has to run into, the less COVID we have in the community. The more people who are protected, the more easy it will be for public health to say, ‘Hey can go ahead and loosen some of these restrictions.’ The risk is going to be lower, even for those people who may not have been vaccinated yet,” Anderson said. “The creation of herd immunity, both through primarily, hopefully vaccination and then people who may have some leftover residual immunity, is hopefully the way forward for us.”

Cases trending downward

While cases are trending downward throughout the country, including significantly so in Dane County, Schwartz doesn’t think it’s because herd immunity has been reached.

“It’s probably multifactorial why we’re seeing a drop of cases,” Schwartz said, pointing out a dip in travel after the holidays and potential behavior changes with concern of coronavirus variants. “Some are questioning if we’re already at herd immunity. The numbers wouldn’t support that. I think there are some other factors at play.”

No matter the reason, it’s welcome news after a spike of cases in the fall.

“I think it’s just probably the best news I’ve had all winter,” Anderson said.