Vaccinated People Don’t Need Mpox Booster Despite Africa Outbreak, Says CDC

Vaccines available at local health departments, clinics and Affirmations

Published: September 17, 2024 | Last Updated: September 17, 2024

As mpox cases continue to surge in Africa, particularly with a severe outbreak in the Democratic Republic of Congo, concerns about waning immunity in high-risk groups, including men who have sex with men (MSM), are resurfacing in the United States.

While the World Health Organization has declared the African outbreak a public health emergency of international concern, the CDC maintains that the risk to the U.S. remains low for now. However, given the disproportionate impact of the 2022 U.S. mpox outbreak on the MSM community, questions are emerging about whether boosters may be needed to protect this vulnerable group as immunity from the Jynneos vaccine may decline over time.

Despite this, the Centers for Disease Control and Prevention (CDC) currently advises that mpox vaccine boosters are not necessary in the U.S., even though concerns about waning immunity have emerged.

Mpox, formerly called monkeypox, spreads through two genetic clades, primarily through sexual contact. The 2022 outbreak in the U.S. involved clade IIb and predominantly impacted MSM, leading to over 30,000 cases. Although vaccination with the Jynneos vaccine — administered in two doses, four weeks apart — helped control the outbreak, there are ongoing concerns about how long immunity lasts in this vulnerable group.

David C. Harvey, executive director of the National Coalition of STD Directors, emphasized the urgency of ensuring the MSM community completes the full two-dose vaccine regimen in an interview with CNN. "Vaccine rates in the U.S. are unacceptably low, especially for people coming back and completing the two doses of vaccine," Harvey said, stressing that only about 25% of the most at-risk population has been fully vaccinated. He added, "The urgent priority now has to be for gay men and bisexual men and other people at risk to get the vaccine now."

While there is evidence that the vaccine-induced immunity from Jynneos may decrease within a year, the CDC reports, two doses may prevent mpox and can reduce the severity of symptoms in those infected with the disease. A recent study conducted by researchers at the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center found that antibody levels after two doses of Jynneos peak around three weeks but decline significantly after a year.

Despite this potential decline in immunity, experts like Dr. Ashish Jha, former White House Covid-19 response coordinator, believe that the current focus should remain on completing the initial vaccination series, especially for the MSM population. "We don’t have enough data right now to recommend boosters for everybody who got previously vaccinated," Jha told CNN. He added that while immunity may wane, vaccinated individuals would likely experience less severe illness if reinfected.

The MSM community remains a high priority for public health officials, as they continue efforts to increase vaccination rates and protect those at risk. Public health experts warn that, without full vaccination coverage, the community could face another outbreak. The CDC and local health departments are staying vigilant, especially in light of ongoing mpox outbreaks globally.

Mpox vaccines are available through local health departments, clinics and organizations, including Affirmations, Ferndale’s LGBTQ+ community center (290 W. Nine Mile) on the following dates:

Wednesday, Sept. 25: 4-7 p.m.
Wednesday, Oct. 9: 4-7 p.m.
Thursday, Oct. 24: 4-7 p.m.
Thursday, Nov. 7: 4-7 p.m.
Thursday, Nov. 21: 4-7 p.m.

Enter your zip code at mpoxvaccine.cdc.gov to find an mpox vaccination site near you.