The 2025-2026 COVID-19 vaccine reduced emergency department and urgent care visits by 50% and hospitalizations by 55%, according to a new peer-reviewed study published in JAMA Network Open.

The study reviewed 85,725 emergency department and urgent care encounters and 26,073 hospitalizations among adults aged 18 and older with COVID-19-like symptoms. The patients weren’t immunocompromised. Researchers compiled the cases using a U.S. Centers for Disease Control and Prevention (CDC) network of 253 emergency departments and urgent care centers and 179 hospitals in seven states, including UCHealth University of Colorado Hospital.

“The study tells us that COVID-19 vaccines are quite effective, and that they’re still an important tool in terms of keeping people from being hospitalized or becoming severely ill,” said Dr. Michelle Barron, UCHealth’s senior medical director of infection prevention and control and a coauthor of the study. “It’s in line with what we’ve seen in the past.”

No 2026 summer spike yet, but COVID still causing serious illness

The COVID-19 pandemic may be something we all would like to forget, but the virus continues to mutate and spread.

Recent data show good news: there hasn’t yet been a summer COVID-19 infection spike related to people spending time indoors in air conditioning. In recent years, a summer spike in COVID-19 cases occurred in July and August. Still, the JAMA Open Network study estimated that there were 390,000 to 550,000 U.S. hospitalizations due to the virus between Oct. 1, 2024, and Sept. 27, 2025, with about 40% of hospitalizations among patients aged 65 and older.

When is the best time to get a COVID-19 vaccine for maximum protection?

As for when to get vaccinated, Barron suggests doing so this fall, when the updated versions of COVID-19 vaccines roll out — ideally as a single-injection combination with a flu shot. COVID-19 infections, like the flu, have historically climbed during the winter months.

Medical experts at the U.S. Food and Drug Administration in May advised vaccine makers to produce vaccines tailored to the dominant XFG variant of the virus’s JN.1 lineage, itself a distant progeny of the omicron strain that brought a global SARS-CoV-2 infection wave starting in late 2021.

COVID-19 vaccines are safe and protect against severe illness

Barron said people should consider COVID-19 vaccines “very safe, and highly effective.”

“There are always going to be side effects associated with a vaccine. Some people have mild soreness in the arm. Some people feel like they need to lie down because they feel so terrible afterwards,” said Barron, who is also a professor of medicine and infectious diseases at the University of Colorado Anschutz School of Medicine.

“But again, side effects are not the same as having an adverse event, and the notion that COVID vaccines put you at a higher risk of developing a stroke, or memory issues, or all sorts of craziness that gets reported, none of that has been substantiated.”

COVID-19 infections increase the risk of several serious health problems, including:

• Short-term risks from the acute illness.
• A substantial increase in the risk of cardiovascular problems.
• Memory and other problems associated with long COVID.

Questions arose about the study, but experts say the data is sound

While there’s little debate about the benefits of COVID-19 vaccines, there was controversy surrounding the publication of these latest vaccine results. They were to have appeared in April in the CDC’s Morbidity and Mortality Weekly Report, but CDC officials declined to publish the findings, citing questions with the study’s statistical approach.

That approach, a test-negative design, considers only patients who seek medical care for the same symptoms (in this case, COVID-19 symptoms). Researchers then calculate the number of people who test positive for COVID-19 and determine which of them received COVID-19 vaccines. Barron said the method is a common way of determining the effectiveness of flu and RSV viruses, among other viruses.

“It’s considered the gold standard,” she said.

And while it’s always wise for researchers and statisticians to evaluate research methods, Barron said the COVID-19 effectiveness data is sound and valuable.

“This is the best version of design that we have for studying vaccine efficacy, and it’s a design that we’ve used for decades,” she said.

Barron urges anyone who may be wary of vaccines to talk with their healthcare providers. Doctors strongly recommend vaccines to prevent COVID-19, flu and other illnesses because they want what’s best for patients.

“Your provider’s goal is to keep you healthy,” Barron said. “Whatever their sense is of the political storms out there, they generally don’t make decisions with politics in mind.”