Mpox vaccine protection fades within 1 year, boosters needed

Antibodies provided by mpox vaccination all but disappear within six to 12 months, new research finds, underscoring the need for boosters to maintain strong protection.

Mpox -- previously known as monkeypox -- is a fast-spreading virus transmitted mainly through close skin-to-skin contact, especially during sex. Its symptoms include fever, painful rashes or sores and swollen lymph nodes.

An mpox outbreak that began in 2022 and was declared over a year later rapidly spread to other countries outside Africa, which had never happened before. Now, the emergence of a new, potentially more severe, strain of the virus in the Democratic Republic of Congo has prompted the World Health Organization to declare a public health emergency of international concern .

As of Sept. 1, the new mpox outbreak in Africa has led to more than 5,265 confirmed cases, 18,737 suspected cases and 617 deaths in 14 African countries, according to the WHO .

"Our study highlights the importance of completing the recommended two-dose mpox vaccine, whether subcutaneous or interdermal, to boost immunity -- regardless of the time between doses," said lead study author Dr. Ai-ris Yonekura Collier , co-director of the Clinical Trials Unit at Beth Israel Deaconess Medical Center (BIDMC) in Boston. "In this mpox outbreak, ensuring broad access to the full vaccine series is crucial."

The new study -- published Thursday in the Journal of the American Medical Association -- suggests that individuals who were vaccinated during the 2022 outbreak need a booster for continued protection.

To arrive at that conclusion, Collier's team gauged immune responses over 12 months in 45 people who got mpox shots during the outbreak or had a confirmed diagnosis of mpox.

Those vaccinated had either one or two doses of Jynneos , the mpox vaccine.

Comparing antibody and T-cell responses at the outset, at three weeks and then every three months until a year had elapsed, they saw that vaccine-generated protection largely waned within six to 12 months.

To contain the 2022 outbreak, public health officials gave priority for vaccination to groups with a particular risk for mpox, including people who had new or multiple sex partners, men who have sex with other men; health care workers and lab personnel; and people who traveled to a destination where the virus has been identified.

Corresponding author Dr. Dan Barouch, director of BIDMC's Center for Vaccine and Virology Research, said in a Beth Israel news release that larger human studies are needed to assess the vaccine's effectiveness over time.

Grants from the National Institutes of Health; the Massachusetts Consortium for Pathogen Readiness; and the NIAID Division of Intramural Research supported the research.

More information

A U.S. Centers for Disease Control and Prevention guide spells out the basics of Mpox vaccination .

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