Pressing ahead with its "mosaic" HIV vaccine, which aims to guard against viral subtypes worldwide, Johnson & Johnson reports that its regimen elicited immune responses that lasted one year after vaccination in phase 1/2a study participants.

In the Approach study, investigators found that all participants who received the lead vaccine regimen maintained an immune response one year after their final shots. The regimen consists of prime doses at weeks 0 and 12, plus booster doses at weeks 24 and 48. J&J presented the data Tuesday at the International AIDS Conference in Amsterdam.

The team previously reported that the regimen induced immune responses in 100% of participants. After unveiling those results, J&J kicked off an efficacy study in five southern African countries in November. Dubbed Imbokodo, the phase 2b study will test the J&J regimen in 2,600 sexually active women between the ages of 18 and 35.

Janssen's Hanneke Schuitemaker, VP and global head of viral vaccine discovery and translational medicine, told FiercePharma enrollment for the efficacy test is on schedule, with 400 women enrolled so far. The company expects the study to read out in 2021. 

An ideal vaccine would provide lifelong protection, Schuitemaker said, but in the meantime, scientists need to focus on programs that can provide durable responses. She previously said the company will have to run other efficacy tests to develop a vaccine that can be used worldwide, but the ongoing study will help to provide a valuable "first look" at efficacy.

The vaccine is designed using computer sequencing to protect against HIV subtypes all over the world, lead investigator Dan Barouch previously told FiercePharma. Barouch serves as director of the Center for Virology at Harvard’s Beth Israel Deaconess Medical Center.

Other HIV vaccine programs are targeted regionally, aiming to protect against viral subtypes in specific parts of the world, he said. And that limits how they would be deployed.

J&J is sponsoring the trial, with additional funding from the Bill & Melinda Gates Foundation and the National Institute for Allergy and Infectious Diseases.

Aside from the J&J efficacy trial, a team that includes the National Institutes of Health, GlaxoSmithKline, Sanofi and others have launched an efficacy test of a separate vaccine regimen. The three-part combo includes experimental vaccines from GSK and Sanofi, plus a GSK adjuvant called MF59. Investigators are testing the regimen in 5,400 sexually active men and women aged 18 to 35 in a phase 2b/3 trial. Results are expected in 2020.

Previously, investigators reported that the regimen was 31.2% effective at preventing HIV infection during a 3.5 year follow-up period in an efficacy trial in Thailand. The team tweaked the regimen to better fight against the virus in South Africa and hopes to improve on those results.