Natural immunity provides some protection, but is inconsistent, doctors say

Published: Sep. 29, 2021 at 6:43 PM AKDT
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ANCHORAGE, Alaska (KTUU) - As the state of Alaska experiences a steep spike in the number of COVID-19 cases and the resulting hospitalizations of patients, 60% of Alaskans have been fully vaccinated. State doctors are hoping to see the number increase in order to keep the burden off of hospitals, but acknowledge that there is some benefit provided by having previously been infected with COVID-19, though it’s not consistent or predictable.

Late last week, Gov. Mike Dunleavy indicated that “at one point” all Alaskans would have some sort of immunity to COVID-19, either through vaccination or natural infection.

“With the number of cases that we’re getting per week and the number of folks that are getting vaccinated, it’s anywhere between 13,000 and 14,000 people a week are now getting the antibodies, either through an infection, or through the vaccination,” Dunleavy said at a press conference held a week ago to discuss the state’s sharp spike, and announce a contract to hire more than 400 traveling health care workers to supplement the state’s worn out, overburdened hospital staff.

“We do (fore)see the surge abating, especially when we get more folks that are going to be immune,” Dunleavy said, “Through one method or another, either through the infection — I suggest the vaccination — but either way, there’s going to be more folks that have the antibodies for this particular variant.”

So far, there have been 108,608 COVID-19 cases in Alaskan residents. It’s unclear how many of those may be repeat infections — someone who catches COVID-19 again after fully recovering from it. There are 364,210 fully vaccinated Alaskans over the age of 12, which accounts for 60% of Alaskans in that age group. Alaska does not yet have data on how many vaccinated Alaskans have already had COVID-19.

Using these numbers, and the Alaska Department of Labor’s state population estimate of 728,903 Alaskans, if no one falls into more than one category of recovered from COVID-19, vaccinated, or re-infected, still only about 66% of Alaskans would have some sort of immunity.

The state’s COVID-19 transmission rate is the highest in the nation. It’s five times higher than the national average, and nearly double that of the state with the next-highest rate. While Alaska still has a low death rate, after leading the nation in vaccine rollout late last year, the state is now in the bottom third when it comes to vaccination rate.

The Alaska Department of Health and Social Services says it will include numbers of reinfections in its upcoming monthly report, covering through the month of August. The amount of COVID-19 activity in the state, which contributed to a backlog in data and crisis standards of care being declared in hospitals and enabled at the state level, has delayed the publication of that report, state epidemiologists said during a public health science presentation Wednesday.

There is some data, though, said State Epidemiologist Dr. Joe McLaughlin, that natural immunity can help fight a re-infection of COVID-19. But, “they’re not protected entirely,” he said.

“There is some immune protection that they have definitely,” he said. “We don’t know exactly what the risk is a year out, after an initial infection, it probably depends on the individual.”

McLaughlin and the state’s other top physicians have long said that natural immunity from a COVID-19 infection varies from person to person, based on many factors. A robust immune system, compromised immune system, and severity of illness would all contribute to the level of immune protection someone would have from a natural infection, he said.

McLaughlin says that the more severe someone’s COVID-19 illness was, the more robust their immune response will likely be a second time.

“They were exposed to so much virus over such a long period of time that their body’s immune system is completely primed and prepped and ready to see another presentation of the virus down the road,” he said.

Dr. Jeffrey Demain, a private practice immunologist in the Anchorage area, said another varying factor in a natural immune response is which part of the virus an individual’s immune system responds to, or “remembers.”

“If it’s responding to the spike protein, there may be a more durable immune response that lasts months, or many months,” Demain said Wednesday. “But if it’s responding to the nucleosome or some other area, not the spike protein, it might not be as durable, because those areas are not very well conserved and oftentimes change in viral mutation.”

The vaccine, on the other hand, Demain said, will only help create antibodies for the parts of the spike proteins, which bind to the receptors in human tissue. The specific makeup of those antibodies is predictable with vaccines.

“That’s one of the reasons we’re not seeing or not anticipating as robust or as likely that they’re going to have prolonged protection,” Demain said.

A study in the state of Kentucky showed that people who had previously had COVID-19 and did not get vaccinated were 2.34 times more likely to get re-infected than those who got vaccinated. The study reports that little real-world epidemiologic studies on the topic so far exist, and that laboratory-only data shows a better neutralization of COVID-19 through vaccination than natural infection.

While vaccination takes weeks to take full effect, there are steps Alaskans can take immediately, that don’t involve drugs or medicines, to slow the spread of COVID-19, McLaughlin said.

“There’s non-pharmaceutical mitigation strategies: masking, social distancing and avoiding crowds, those are effective today,” he said.

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