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

Overview

Updated May 30

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: the bacterium living on every human face produces two versions of the same enzyme. Which version dominates determines whether skin stays clear or breaks out.

The discovery led to 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. 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.

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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

Lead researcher; Professor and Chief of Pediatric Infectious Diseases, UC San Diego School of Medicine

Leading preclinical development of selective acne vaccine

Chun-Ming Huang

Earlier UC San Diego acne vaccine researcher

Pioneered CAMP factor vaccine approach

Organizations Involved

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

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

January 2004 April 2024

6 events Latest: April 1st, 2024 · 2 years ago

Tap a bar to jump to that date

April 2024
Sanofi launches Phase I/II mRNA acne vaccine trial
Latest 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.
April 1st, 2024
December 2023
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.
December 5th, 2023
December 2021
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.
December 1st, 2021
June 2018
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.
June 1st, 2018
January 2011
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.
January 1st, 2011
January 2004
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.
January 1st, 2004

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

1986

Recombinant Hepatitis B vaccine (1986)

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.

Then

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

Now

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 this matters now

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.

1991–2006

HPV vaccine development (1991–2006)

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.

Then

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

Now

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 this matters now

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.

2020

COVID-19 mRNA vaccines (2020)

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.

Then

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

Now

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 this matters now

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.