Report: One-third of Alaska COVID-19 cases in August were due to vaccine breakthrough

ANCHORAGE, Alaska (KTUU) - As the highly transmissible delta variant of the coronavirus was discovered in Alaska, it quickly took over. The state has seen a sharp increase in COVID-19 cases and hospitalizations since that first case was discovered, and the variant now represents more than 99% of cases sequenced in the state of Alaska in the month of August, and continuing through September.

The state released its monthly report of COVID-19 cases through August, examining multiple facets of the pandemic’s effects on Alaska. Many concerned about the specter of vaccine mandates have questioned the efficacy of the vaccines, due to the existence, and increasing number, of vaccine breakthrough cases, which are when someone fully vaccinated against COVID-19 gets infected with the virus anyway.

According to the report, 33.6% of all Alaska COVID-19 cases during the month of August were due to vaccine breakthrough. That’s up from the 29.6% of all July cases that occurred in people who were fully vaccinated. The majority of cases, deaths and hospitalizations are still among unvaccinated people.

But state health professionals say the new data shows what they’ve expected — that increased circulation of COVID-19, and the larger number of people being vaccinated, would lead to more vaccine breakthrough infections.

“That percentage is going to go up over time for a couple reasons,” said Dr. Joe McLaughlin, the state epidemiologist, in a media call last week. “The proportion of people who are fully vaccinated increases over time, so you have a larger number of people in the fully vaccinated group than the unvaccinated group, at over 50% of our population now fully vaccinated. So as that number goes up, we’re going to see more vaccine breakthrough cases.”

Other factors leading to more breakthrough cases are waning immunity as people get further from their date of vaccination, and that older people and those with compromised immune systems may not have built an adequate immune response to their vaccination to begin with.

According to the state’s data, vaccine breakthrough cases have increased greatly in the proportion of overall cases since the delta variant was first detected in Alaska. While no Alaskan was considered “fully vaccinated” (two weeks out from the final dose of any of the three U.S. authorized manufacturers’ series) until Jan. 16, 2021, there were two “breakthrough” cases in that time period.

Since then, the numbers have crept up. February saw 1.5% of overall cases that month in fully vaccinated people. In March, when vaccines became available to all Alaskans over 16, vaccine breakthrough cases made up 3% of all COVID-19 cases that month. Of the total cases in April, 5.2% were due to vaccine breakthrough, as were 8.8% of all cases in May, which is when vaccines became available to all Alaskans 12 and older.

The first case of the delta variant was identified in a state lab the week of May 30. In June, the number of vaccine breakthrough cases nearly tripled, to 22.8% of all cases that month. In June, there were 790 COVID-19 cases reported to the state. In July, the state saw more than June’s total cases in breakthrough cases alone, with 29.6% of July’s 4,134 reported COVID-19 cases being in people who were fully vaccinated. In August, 33.6% of the state’s 12,816 cases were breakthrough infections. The number of breakthrough cases again numbered more than the previous month’s total COVID-19 cases.

The distribution of vaccine breakthrough cases varied based on age range. In August, those 65 and older saw the highest rate of vaccine breakthrough cases out of all age groups, even though that age range also has the highest rate of vaccination at 74.7%. That statistic supports the recent Centers for Disease Control and Prevention recommendation for seniors 65 and older to get a third dose, or booster shot, of the Pfizer vaccine.

Even though more than one-third of COVID-19 cases in August were in people considered fully vaccinated, more than 58% of eligible Alaskans have been fully vaccinated, and health officials emphasize that even if someone gets a vaccine breakthrough case of COVID-19, they are 9.1 times less likely to be hospitalized with it than if they’re not vaccinated.

State numbers show that 96 Alaskans in July and August were hospitalized with vaccine breakthrough infections of COVID-19. The state’s monthly report does not include cases of people who were hospitalized for something else not related to COVID-19, though those positive cases are included in the daily hospital counts. Patients with COVID-19 are kept in the COVID-19 ward with special health care protocols. The hospitalization data also includes only cases that have a discharge date — patients who were hospitalized from COVID-19 and are still in inpatient care are not included in these numbers.

Of those 96 people hospitalized, more than two-thirds were over 65, and they accounted for one-third of the hospitalizations of people their age. Thirteen fully vaccinated people between 12 and 49 were hospitalized with COVID-19 in July and August, and 17 people ages 50-64.

The rise in proportion of breakthrough cases shows in hospitalizations as well. In April, 6.3% of hospitalized COVID-19 patients were fully vaccinated. In May, that statistic grew to 4.5%, then 11.9% in June and 19.1% in July. That proportion stayed nearly identical in August with 19% of COVID-19 hospitalizations that month being people who were fully vaccinated.

Since the delta variant came into play, McLaughlin said the proportion of fully vaccinated people to unvaccinated people has remained roughly stable.

“The cases are increasing, but proportionally they’re pretty consistent,” he said.

According to the Department of Health and Social Services, since January 16, when the first Alaskans to be vaccinated reached the two-week mark, through Sept. 18, 2021, hospitalized COVID-19 patients who were unvaccinated or only partially vaccinated had a median age about 16 years younger than the age of fully vaccinated patients who were hospitalized. Those numbers reinforce what Alaska’s health professionals have been saying in recent months — that since the surge of delta cases, patients have tended to be younger and sicker than in the past.

“There’s just over a 20-year age gap between unvaccinated and vaccinated individuals in the hospitals in Alaska,” Alaska Chief Medical Officer Dr. Anne Zink said in a media call earlier this month. “People who are unvaccinated are 20 years younger than those who are vaccinated. So again, these tools work well to keep you out of the hospital, including vaccines.”

Of the 120 COVID-19 deaths recorded in July and August by the time the report was compiled, just over one-fourth, or 31, were people who were fully vaccinated. Just six other fully vaccinated people were reported as dying with COVID-19 through the entire pandemic.

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