COVID-19: Curing misconceptions about herd immunity

As COVID-19 infections continue to grow across the country and Nome sees its first major outbreak, misinformation continues to spread about the deadliness of the virus and the effectiveness of the measures that protect against it.

One particularly misunderstood concept is herd immunity, the idea that if a large enough proportion of people become immune through infection, the virus would lose the ability to spread. In public meetings, some have argued that if the community just let the virus run its course, eventually enough people will recover and become immune so that the virus naturally dies out. But experts unanimously warn that such a policy would be catastrophic.

Herd immunity is indeed how most doctors believe the world will solve the pandemic, but acquired in a different way than letting the virus run rampant. An effective vaccine, once it becomes widely available, will be able to immunize enough people that the virus can’t spread from patient to patient, effectively eliminating it.

But herd immunity ushered in by a vaccine is very different from herd immunity by mass infection. Because of the high mortality rate of COVID-19 compared to other viruses, herd immunity from mass infection would be a “public health disaster” according to a report from Johns Hopkins University.

Not everyone in a community needs to be immune for herd immunity to take effect. Doctors estimate that after around 70 percent of a population is immunized, the virus can’t jump from susceptible person to susceptible person quickly enough to stay alive. But a 70 percent infection rate of the population would lead to huge mortality rates.

Pinning down the precise mortality rate of COVID-19 is difficult, since age and preexisting conditions play a role in who gets sick – the virus will have a much higher mortality among older people than younger ones. Johns Hopkins reports that, so far, the U.S. has recorded about 12.2 million cases and about 257,000 deaths, for a mortality rate around one percent. Globally, they report about 59 million cases and 1.4 million deaths, for a mortality rate of over two percent.

Those numbers contain room for error. Many cases, as well as many COVID-related deaths, go undiagnosed or unreported – but even at an average mortality rate of one percent, more than two million Americans would die before herd immunity was achieved through mass infection.

In the Norton Sound/Bering Strait region, that would mean that at least 70 people die before the virus “ran itself out” and the region achieved herd immunity.

But that number doesn’t capture all the damage. In addition to those deaths, a large number of infections would cause a surge in patients needing critical medical care, which would overwhelm local and state healthcare systems and cause even more people to die of both COVIDand non-COVID-related emergency illness.

Also, the long-term effects of COVID-19 infections are not well understood, and some survivors experience debilitating symptoms for months that may cause irreparable damage to their lungs and other organs.

The other caveat is that doctors still don’t know how long immunity will last. If a mild infection doesn’t result in lasting immunity, then herd immunity by mass infection would be for naught.

While the Centers for Disease Control estimate that recently recovered patients are immune to the virus for at least 90 days, reinfections have been known to occur. Scientists are still unsure of how common and how serious reinfections are, but that uncertainty poses another argument against herd immunity by unchecked virus spread.

Dr. Mark Peterson, Medical Director of Norton Sound Health Corporation, said that while the region’s case counts have been low so far, it wouldn’t take much for the region to reach crisis mode. He pointed to the Yukon-Kuskokwim region, where testing and quarantine for travelers have not been as strict, as an example of what could happen in the Bering Strait/Norton Sound region if the virus gets out of control. “It didn’t take long for Bethel [YK region] to go from 40 active cases to 2,000 active cases,” he said. “It was just a couple months ago that they were starting to see more cases, and now they’re seeing 50 to 100 every day.”

With those high numbers have come five to ten active cases in the Bethel hospital at any given time, as well as multiple deaths in the region.

Dr. Peterson added that the Bethel hospital had to call three or four other hospitals around the state to find space for patients needing advanced care for both COVID- and non-COVID-related illness, as in

creased case numbers around Alaska begin to overwhelm healthcare networks.

In just eight weeks, he said, the Nome hospital could be facing similar problems if case numbers aren’t kept in check by diligent social distancing around the community. The most recent outbreak in Nome took all of NSHC’s energy to contain, and if that outbreak had been bigger or coincided with an active village outbreak, he said, they would have been overwhelmed.

“Unfortunately, because we’re so remote, it makes it so much more difficult to provide the layers of care that are needed,” Dr. Peterson said. “Those with severe symptoms that need a critical care unit, they’ve got to be shipped out. We are much more vulnerable in the rural areas.”

Of the approximately 200 cases in the region so far, no patients have needed critical care, but Dr. Peterson said it could happen any time. The number one way to decrease the chance of the virus reaching a vulnerable resident, he said, is to limit the number of cases in the region.

He added that the end was likely in sight. Although important questions still remain about the duration of immunity and the distribution of vaccines, clinical trials for multiple vaccines show promising results, and he estimated that by the end of spring 2021, there may be enough effective vaccine available in the region to ease many restrictions. The challenge is to minimize loss of life until that happens.

“It’s actually pretty easy not to get COVID,” he said. “You just have to do all the right things.” In addition to mask wearing and six-foot social distancing, Peterson emphasized the importance of keeping close contact bubbles small, especially during the holidays.

“You should only have your family that lives in your house as your close contacts right now,” he said. “You shouldn’t be visiting with anybody else. At work you should be distancing. If people would do that, then we will not have significant spread in our villages or in Nome.”