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Researchers identify why the same skin bacterium causes acne in some people but not others

Researchers identify why the same skin bacterium causes acne in some people but not others

New Capabilities

UC San Diego team discovers two enzyme variants that determine whether common skin bacteria trigger inflammation or promote health, opening a path toward a selective acne vaccine

April 1st, 2024: Sanofi launches Phase I/II mRNA acne vaccine trial

Overview

Nearly a billion people worldwide have acne, and for decades, the best medicine could offer was topical creams that irritate skin, antibiotics that breed resistance, or a powerful drug — isotretinoin — that causes birth defects. On December 5, 2023, researchers at UC San Diego published a finding that reframes the problem entirely: the bacterium living on every human face produces two versions of the same enzyme, and which version dominates determines whether skin stays clear or breaks out.

The discovery enabled a precision vaccine that, in mice, cut acne inflammation roughly in half — not by wiping out the bacterium, but by neutralizing only the harmful enzyme while leaving its beneficial twin intact. The work arrives as pharmaceutical giant Sanofi separately pushes an mRNA-based acne vaccine into human clinical trials, meaning two distinct approaches are now racing toward what would be the first preventive treatment for the world's eighth most common disease.

Why it matters

A billion people have acne and current treatments all carry serious side effects — a vaccine could change that.

Play on this story Voices Debate Predict

Key Indicators

~1 billion
People affected by acne worldwide
Acne is the eighth most common disease globally, affecting up to 80% of adolescents
~50%
Inflammation reduction in mouse model
The selective peptide vaccine cut acne-related inflammation roughly in half compared to unvaccinated controls
5–10 years
Estimated time to public availability
Lead researcher George Liu's projection for the UC San Diego vaccine reaching patients
400
Participants in Sanofi's mRNA acne vaccine trial
Sanofi launched a Phase I/II clinical trial in April 2024 for a competing mRNA-based approach

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People Involved

George Y. Liu
George Y. Liu
Leading preclinical development of selective acne vaccine
 Chun-Ming Huang
Chun-Ming Huang
Pioneered CAMP factor vaccine approach

Organizations Involved

UC San Diego School of Medicine
UC San Diego School of Medicine
Academic Research Institution
Conducting preclinical acne vaccine research

The university's medical school has housed two parallel lines of acne vaccine research over the past decade, targeting different bacterial proteins.
Sanofi
Sanofi
Pharmaceutical Company
Running Phase I/II clinical trial for mRNA acne vaccine

The French pharmaceutical giant acquired Austrian biotech Origimm in 2021 and pivoted its acne vaccine candidate to mRNA technology, entering human trials in 2024.

Timeline

  1. Sanofi launches Phase I/II mRNA acne vaccine trial

    Clinical Trial

    Sanofi began enrolling approximately 400 adults aged 18–45 with moderate to severe facial acne in a Phase I/II trial testing its mRNA-based vaccine at multiple dose levels.

  2. UC San Diego publishes HylA/HylB enzyme discovery

    Research

    George Liu's team published in Nature Communications that two variants of hyaluronidase — HylA (inflammatory) and HylB (anti-inflammatory) — explain why the same bacterium causes acne in some people but not others. A selective peptide vaccine reduced inflammation by approximately 50% in mice.

  3. Sanofi acquires Origimm Biotechnology

    Industry

    Sanofi purchased Austrian biotech Origimm, gaining its early-stage acne vaccine candidate ORI-001 and pivoting the program to mRNA technology.

  4. CAMP factor antibodies reduce inflammation in human acne tissue

    Research

    A study in the Journal of Investigative Dermatology showed that monoclonal antibodies targeting the CAMP factor markedly reduced inflammatory markers in human acne explants.

  5. UC San Diego begins CAMP factor vaccine research

    Research

    Researchers at UC San Diego began investigating the CAMP factor, a toxin produced by C. acnes, as a potential vaccine target. Mutations to the gene significantly reduced bacterial colonization and inflammation in mice.

  6. C. acnes genome fully sequenced

    Research

    Publication of the complete genome of Cutibacterium acnes opened the door to identifying specific virulence factors as vaccine targets.

Scenarios

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1

mRNA acne vaccine reaches market by late 2020s

Sanofi's mRNA vaccine shows strong efficacy in Phase I/II trials, moves to Phase III by 2027, and reaches regulatory approval by 2029–2030. As the better-funded and more clinically advanced program, it becomes the first acne vaccine on the market. The projected $2 billion-plus annual revenue validates the category and attracts additional competitors.

Discussed by: Sanofi corporate projections; dermatology industry analysts
Consensus —
2

UC San Diego's selective approach proves superior, enters clinical trials

Liu's precision approach — targeting only the pathogenic enzyme — proves more effective or safer than Sanofi's broader mRNA vaccine in clinical testing, because it preserves the beneficial functions of C. acnes on skin. This would validate the microbiome-aware approach to vaccine design, though the 5–10 year timeline means it would likely reach patients after Sanofi's candidate.

Discussed by: Academic immunologists; microbiome researchers
Consensus —
3

Clinical trials reveal acne vaccines don't work well enough in humans

Mouse models of acne are imperfect stand-ins for human skin. If either vaccine shows marginal efficacy in human trials — reducing acne by less than existing treatments — the entire vaccine approach could stall. Acne's multifactorial nature (hormones, diet, genetics, and multiple bacterial strains) may prove too complex for a single-target vaccine to meaningfully address.

Discussed by: Skeptical dermatologists; vaccine development researchers
Consensus —
4

Acne vaccines become standard adolescent immunization

If one or both vaccines demonstrate strong efficacy and safety, acne vaccination could eventually join the standard adolescent immunization schedule — similar to the path taken by the HPV vaccine. Given acne's near-universal prevalence in teenagers and its documented psychological toll, the public health case would be compelling. This scenario likely requires a decade or more of clinical evidence.

Discussed by: Public health advocates; pediatric dermatologists
Consensus —

Historical Context

HPV vaccine development (1991–2006)

1991–2006

What Happened

In 1991, immunologists Ian Frazer and Jian Zhou at the University of Queensland developed virus-like particles that could train the immune system to fight human papillomavirus without using live virus. After 15 years of development and clinical trials, the FDA licensed Merck's Gardasil vaccine in June 2006. Over 100 countries have since added it to their immunization programs.

Outcome

Short Term

HPV vaccination rates among eligible adolescents climbed steadily, reaching over 60% in the United States within a decade of approval.

Long Term

Countries with early adoption are now seeing measurable declines in cervical cancer rates — the first generation partially protected from a cancer that kills over 300,000 women per year globally.

Why It's Relevant Today

The HPV vaccine established the precedent for vaccinating against a near-universal condition (most sexually active people contract HPV) to prevent its serious downstream consequences. An acne vaccine would follow a similar logic: targeting a nearly universal condition to prevent physical and psychological harm.

Recombinant Hepatitis B vaccine (1986)

1986

What Happened

Merck developed Recombivax HB, the first vaccine to use recombinant DNA technology — producing a viral protein in yeast cells rather than using blood-derived material. The approach eliminated the contamination risks of earlier plasma-derived hepatitis B vaccines and demonstrated that targeted protein engineering could replace crude whole-pathogen approaches.

Outcome

Short Term

Universal infant hepatitis B vaccination was adopted in the United States by 1991 and globally through WHO recommendations.

Long Term

The recombinant platform became the foundation for subsequent precision vaccines, including HPV vaccines, and proved that targeting a single protein could provide effective immunity.

Why It's Relevant Today

Liu's selective peptide vaccine follows the same philosophical arc: rather than targeting the whole bacterium, it isolates one specific protein variant. The recombinant hepatitis B vaccine proved this precision approach could work at scale.

COVID-19 mRNA vaccines (2020)

2020

What Happened

Moderna and Pfizer-BioNTech developed mRNA vaccines against SARS-CoV-2 in under a year, compressing a process that typically takes a decade. The technology instructs human cells to produce a target protein, training the immune system without introducing any pathogen material. Both received emergency use authorization in December 2020.

Outcome

Short Term

Over 13 billion COVID-19 vaccine doses were administered globally within two years, demonstrating that mRNA manufacturing could scale rapidly.

Long Term

mRNA technology became a platform for vaccines against other conditions. Sanofi, Moderna, and others began applying it to cancer, respiratory viruses, and now acne.

Why It's Relevant Today

Sanofi's mRNA acne vaccine is a direct descendent of the COVID-19 mRNA platform. The pandemic proved mRNA vaccines could be manufactured at scale; the acne application tests whether the technology can work against chronic inflammatory conditions, not just acute infections.

Sources

(8)
+2
Nature Communications UC San Diego Today Human Progress Sanofi CenterWatch Journal of Investigative Dermatology Live Science Nature