University of Iowa aids research showing benefits of updated COVID booster

Pharmacy technician Suzanne Eagan draws a dose of Pfizer-BioNTech COVID-19 vaccine from a vial at the University of Iowa Hospitals and Clinics in Iowa City, December. (Andy Abeyta/The Gazette)

Although only 39 percent of Americans age 65 and older received both the first COVID vaccine series and an updated bivalent booster shot against the Omicron strain, new research from the University of Iowa shows “significant protection” from this bivalent vaccine in these older adults.

Specifically, it found that Americans in this older age group who received the updated booster shot were 84 percent less likely to be hospitalized with COVD than unvaccinated individuals and 73 percent less likely to be hospitalized with COVD than those who had up to one were vaccinated to some degree — but not with a bivalent booster, according to a study released Dec. 30 by the US Centers for Disease Control and Prevention.

“These new results suggest that the bivalent shot is a valuable tool to protect vulnerable individuals at a time when COVID-19 case numbers are rising again,” said Nicholas Mohr, professor of emergency medicine, anesthesia and epidemiology at UI. in a statement, citing research on counseling, “older adults are receiving the bivalent booster to maximize their protection against COVID-19 during the winter months.”

Nationwide, 414,721 COVID cases were reported for the week of Jan. 11 — up from weekly counts in the 200,000s in October and November, and down from weekly counts below 200,000 in March and April. Weekly COVID deaths nationwide rose to 3,907 on Jan. 11, up from 2,705 the week before.

In Iowa, weekly cases have stabilized at over 2,000 lately – down from the summer months when weekly case numbers approached 6,000. But weekly deaths in the state rose from the teens to 46 on January 11 and into the low 20s in November and December.

The CDC’s Advisory Committee on Immunization Practices on Sept. 1 recommended Americans receive the bivalent booster shot against the Omicron variant because preventing COVID hospitalizations remains a core goal. But the uptake was small and slow.

About 16 percent of Americans ages 5 and older have received the updated refresher, 18 percent among those ages 18 and older and 39 percent among those ages 65 and older, according to the CDC. Now, 94 percent of Americans age 65 and older have completed their primary vaccination course, as have 79 percent of those over the age of 18.

Missing data

The reasons for the low intake are “complex,” said Mohr. However, because previous research has shown that immunity to the primary vaccine series wanes over time, research into the effectiveness of the booster vaccine was important to encourage more to receive the vaccine.

“There is a lack of data on the effectiveness of a bivalent booster vaccine against COVID-19 hospitalizations in the United States,” says the study, which set out to change that by drawing on a network of research organizations — including UI hospitals and clinics and her College of Medicine.

Between Sept. 8 and Nov. 30, 22 hospitals in 18 states admitted 798 patients ages 65 and older — including 381 who tested positive for COVID and 417 who were hospitalized with COVID symptoms but tested negative.

Study participants were divided into three groups: unvaccinated; vaccinated with two or more doses of the original monovalent mRNA vaccine; and vaccinated with the basic immunization plus a bivalent booster vaccination.

Of the 381 case patients who tested positive for COVID, 21 percent were unvaccinated, 73 percent received the primary series of vaccines, and only 5 percent had received a bivalent booster dose. Of the 417 control patients who did not test positive, 15 percent were unvaccinated, 71 percent received the primary vaccine course, and 14 percent had the bivalent booster vaccine.

The study showed that the bivalent booster shot provided “strong protection” against COVID hospitalizations, which is significant because nearly nine in 10 of the approximately 400 Americans who die from COVID every day are over the age of 65, UIHC officials said .

“These early results, from a cohort of adults ≥ 65 years of age, 74 percent of whom had multiple underlying conditions, are among the first to document real-world evidence that receiving a bivalent booster dose after completion of at least one primary COVID-19 -Illness occurs The mRNA vaccine series protects against COVID-19 hospitalizations,” the study said.

“Continued monitoring will be important to understand the continued protection associated with the expansion of Omicron sublines and emerging variants, and to understand whether fading in immunity induced by bivalent vaccines is observed over time, similar to how after a monovalent COVID-19 mRNA vaccine doses.”


The bivalent booster study, specific to older Americans, is among a growing list of COVID-related research in which UI Health Care is involved, continues to be involved or is leading, including testing the continued efficacy of the primary vaccines and booster shots.

Using health workers as research subjects, this study additionally aims to identify differences in vaccine efficacy by age; by job and category; by vaccine brand and dosage; by history of infection; and against emerging variants.

The university also participates in studies on new COVID vaccines, therapies and long-lasting symptoms.

Vanessa Miller reports on higher education for The Gazette.

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