More evidence continues to emerge that being up-to-date on the COVID-19 vaccination series is important during the current surge.
Being up-to-date on vaccinations — which means getting all recommended doses, including a booster dose if eligible — is particularly important as virus case counts soar from the highly transmissible omicron variant.
And while omicron has driven up cases among not only the unvaccinated but those who are vaccinated as well, vaccinated Alaskans who received their booster shots were much better protected against symptomatic COVID-19 compared to their un-boosted counterparts during the state’s current surge.
That’s according to a new study published Wednesday by the Alaska Department of Health and Social Services.
Alaskans showing symptoms of the virus who got a booster dose of the COVID-19 vaccine were three times less likely to test positive compared to those who had only received the primary course of their vaccines and were eligible for a booster but hadn’t received one yet, according to the study.
“The most important takeaway is that boosters lead to prevention of symptomatic COVID during the omicron era,” said Eric Mooring, an epidemiologist and CDC assignee to the state of Alaska’s Division of Public Health who helped author the study.
As the omicron wave hit, case counts rose sharply, but people who were up-to-date on vaccinations were still less likely to get COVID-19 compared to people who were unvaccinated, according to Mooring.
“One way to think about this analysis is it shows that the vaccines do continue to work against the omicron variant,” he said.
A similar study conducted nationally and published in the Journal of the American Medical Association last month found that three doses of an mRNA vaccine provided better protection against the delta variant and especially the omicron variant of the virus.
The Alaska study took place over a month — from late December to late January — when omicron was surging through the state. The researchers sought to study people who were seeking a COVID-19 test for the same reason: They all had symptoms, Mooring said.
The researchers further zeroed in on a specific group: Alaskans who were vaccinated, including those who had received a booster and those who hadn’t. Those included in the study could not have had a documented case of the virus in the past 90 days and must have also reported at least one COVID-19 symptom.
That turned out to be around 5,184 people total, over half of whom got tested in Anchorage. Out of the group, 2,318 tested positive and 2,866 tested negative. (For broader context, during the same time period, over 37,000 Alaskans total — vaccinated and unvaccinated — tested positive.)
Researchers then compared the booster history of the people within the group who tested positive for the virus against people who tested negative.
The results showed that 28% of people who tested positive had received their booster dose while 72% who tested positive were eligible for a dose but hadn’t received one yet. As a point of comparison, of those who tested negative, 54% were boosted and 46% were not boosted but were eligible for the shot.
“The distinction in boosted versus not boosted between these two groups is a signal that all else equal, the boosting is making a difference in how likely people are to have COVID,” Mooring said.
Since the omicron wave hit later in Alaska than in other places, researchers haven’t been able to study hospitalization and death rates during the surge, but Mooring said analyses from hospitals around the country found that people with three doses of the vaccine were strongly protected against severe illness requiring hospitalization.
And just because people still test positive many months after vaccination doesn’t mean the shots aren’t effective. National studies have also shown that people recently vaccinated, who are also considered up-to-date since they’re not yet eligible for a booster, are also significantly protected against omicron, Mooring said.
“People who get the primary series would have that high level of protection, probably similar to boosted people,” he said.
Broad preliminary data showed that throughout 2021 and the early part of this year, among Alaska residents age 5 and older who had their initial vaccine series and were considered fully vaccinated, 404 were hospitalized with COVID-19 and 140 died. Meanwhile, 1,697 unvaccinated Alaskans were hospitalized with the virus and 565 unvaccinated Alaskans died due to COVID-19 during the same time frame.
The recent research on the effectiveness of booster doses “is a reminder and good evidence that supports what we have long thought to be the case — namely that vaccines work as well in Alaska as they do anywhere else,” Mooring said.