Experts Warn of Ongoing Monkeypox Threat Despite Progress in Vaccination and Behavioral Changes | AIDS 2024

Although much progress has been made in managing the current monkeypox (mpox) outbreak with vaccines and changes in behavior, it remains crucial to stay alert and adapt new strategies to prevent future crisis, according to co-presenters at the International AIDS 2024 Conference in Munich, Germany who presented on the current mpox outbreak this week.

Currently, the world is experiencing the spread of the Clade 2b monkeypox virus.

Mpox was introduced 60 years ago, traditionally being transmitted from animals to humans through bites, scratches or contaminated meat. However, the 2022 outbreak saw a dramatic shift, with the virus primarily spreading through close contact during sex.

Initially identified in monkeys, mpox was first found in humans in 1970 in the Democratic Republic of Congo, according to Chloe Orkin from the SHARE Collaborative Centre for Immunobiology.

Today, the clade 2b outbreak has reached alarming proportions, with over 94,000 confirmed cases reported across 117 countries, including significant numbers in the U.S. and Brazil, and up to 103 deaths.

Orkin highlighted how declining herd immunity, due to waning smallpox vaccination coverage, and rapid viral evolution played a role in the pandemic’s severity.

To date, Clade 2b has been found to affect younger men who have sex with men (MSM), who are linked to high rates of HIV co-infection.

Andrea Antinori from the Istituto Nazionale per le Malattie Infettive Lazzaro Spallanzani, shared Italy’s response to the outbreak.

Italy reported over 1,000 cases of monkeypox, mainly among men, between May and December 2022.

The Italian vaccination campaign, launched in August 2022, used the modified vaccinia Ankara-Bavarian Nordic vaccine and targeted high-risk populations, such as MSM.

Over 6,000 doses were administered, covering 44% of the target population, including individuals with HIV and those on preexposure prophylaxis (PrEP).

Antinori highlighted the success of Italy’s vaccination strategy, noting a significant decline in cases following the campaign.

“The decrease was likely due to a combination of reduced risk behavior, public health factors, and probably even the effect of the vaccination campaign,” he said.

Also supporting the successful response in Italy, he discussed how using intradermal vaccine shots has been helpful for saving on vaccine doses, although this method can cause more local reactions, such as redness or swelling, it’s just as effective as the traditional subcutaneous shots.

In addition, previous studies conducted over time have shown that the vaccine continues to work effectively, with strong immune responses lasting well after getting both doses.

Antinori did, however, stress the need for ongoing vaccination efforts and potential booster doses, especially for those previously infected, to manage and mitigate the outbreak in Italy effectively.

Vaccine uptake and behaviors among sexual and gender minorities in response to the outbreak were also addressed during the session.

Drawing on U.S. data, Christian Grov from the CUNY Graduate School of Public Health and Health Policy, provided valuable insights into the outbreak’s trajectory, response strategies and continous challenges.

Grov observed that bisexual individuals, those not engaged in PrEP care and those not in HIV care were less likely to get vaccinated. He also noted significant disparities in vaccine access, with White individuals more likely to receive vaccines compared to people of color.

In response to the success rate in Italy, Grov stressed the importance of behavioral changes, community collaboration and vaccination in controlling the outbreak. He reflected on the similarities between Italy's and the U.S.’s vaccine rollouts, noting the vaccine rollout in Italy mirrored what happened in the U.S.

He also addressed vaccine resistance among certain groups, stating, “What I want you to know is that we saw significant resistance to the vaccine among people who had not received it, which started to increase as the initial epidemic began to wane.”

In a study involving over 8,000 individuals recruited mainly from “hookup” apps, Grov presented its data revealing that while participants initially reduced their number of sex partners and engaged in fewer sex acts, behaviors reverted as the outbreak waned.

Vaccine uptake increased initially but plateaued, with only 35% of participants having received at least one vaccine dose by November 2022, leaving many still vulnerable.

Though this study had limitations such as potential duplicate responses and the need for better-worded questions, Grov highlighted the critical need for continued vigilance and vaccination efforts to prevent future outbreaks, noting that many individuals remain at risk for monkeypox.