• Posted June 26, 2025

Updated COVID Vaccines Effective Against New Strains

Updated COVID-19 vaccines are keeping up with new coronavirus strains and remain effective for keeping people out of the hospital, a new study says.

The study, which examined the effectiveness of the 2023-2024 COVID vaccines against the XBB and JN.1 Omicron variant waves, found that the updated shots caused:

• A 24% lower risk of ER and urgent care visits related to COVID.

• A 29% lower risk of hospitalization.

• A 48% lower risk of ICU admission or death in hospital.

This protection stretched from a week after vaccination out to 299 days afterward, researchers reported June 25 in JAMA Network Open.

Maximum protection came during the first two months after vaccination, reducing severe cases of COVID by up to 68%, results show.

However, vaccine effectiveness waned over time, particularly beyond the six-month mark.

“This study demonstrates that the updated COVID-19 vaccines continue to offer significant protection against severe outcomes like hospitalization and critical illness, especially in the months immediately following vaccination,” study co-author Dr. Shaun Grannis, vice president for data and analytics at the Regenstrief Institute, said in a news release.

“These findings reinforce the importance of staying up to date with recommended vaccines, particularly for our older and more vulnerable patients as the virus continues to evolve,” he said.

These findings come as government actions have placed roadblocks in the way of updated COVID vaccines.

In May, the U.S. Food and Drug Administration (FDA) announced that it won’t approve updated COVID vaccines for the general public unless they’ve been subjected to placebo-controlled trials.

Later that month, Health and Human Services Secretary Robert F. Kennedy Jr. said that the U.S. Centers for Disease Control and Prevention (CDC) would no longer recommend the COVID vaccine for healthy children or healthy pregnant women. The CDC’s website has not been updated to reflect Kennedy's orders.

For this new study, researchers analyzed data on more than 345,000 ER or urgent care visits and more than 111,000 hospitalizations among U.S. adults with a COVID infection.

The COVID cases came from six health care systems in eight states — Oregon, Washington, Utah, Colorado, Indiana, Minnesota, Wisconsin and California. All told, the cases were treated at 241 hospitals and 373 ERs and urgent care centers, the study says.

Researchers compared these cases against electronic health records reflecting lab and vaccination records running from September 2023 to August 2024, when the XBB and JN.1 COVID variants were predominant.

Results show that protection was especially significant for adults 65 and older, supporting guidelines that recommend timely vaccination and additional doses for high-risk groups, researchers said.

“Our findings show that the updated COVID-19 vaccines continue to provide protection against severe illness and hospitalization,” researcher Brian Dixon, director of the Regenstrief Center for Biomedical Informatics, said in a news release.

“Effective vaccines remain a critical tool in keeping communities healthy and reducing costs associated with COVID-19 infection by preventing hospitalizations and emergency department visits,” Dixon added.

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19 vaccine guidelines.

SOURCE: Regenstrief Institute, news release, June 25, 2025