Former Research Chimpanzees Receive Comprehensive Health Checks at Liberia Sanctuary

In August 2026, a cohort of chimpanzees that had been used in hepatitis B vaccine experiments from the 1970s through the early 2000s underwent full medical examinations at the Second Chance Chimpanzee Refuge in central Liberia. The checks, performed under anesthesia, included dental cleaning, X-rays, blood work, and vaccinations, and were intended to establish baseline health data and guide long-term care plans.

Chimpanzees used for vaccine research get health checks as part of long-term care

More than 400 West African chimpanzees were captured as infants and employed by American researchers in hepatitis B vaccine trials spanning several decades. By the early 2000s the program ended, leaving a surviving population of animals with varied histories of invasive procedures. In 2015 the nonprofit Humane World for Animals assumed permanent responsibility for the 60 individuals that remained at the conclusion of the research program. The sanctuary now houses the chimps on a series of mangrove-covered islands, providing a naturalistic environment for their retirement.

Chimpanzees used for vaccine research get health checks as part of long-term care Baby Chimpanzees Develop Distinct Regional Accents, Study Finds Discover Magazine

• Original research cohort: > 400 chimpanzees used in vaccine studies.

Chimpanzees used for vaccine research get health checks as part of long-term care

• Sanctuary residents (as of 2025): 60 former research subjects.

Chimpanzees used for vaccine research get health checks as part of long-term care

• Health-check components: dental examinations, cardiac and pulmonary assessments, neurological evaluation, blood panels, booster vaccinations, and nail trimming.

Chimpanzees used for vaccine research get health checks as part of long-term care

• Average age of the chimpanzees: 30–35 years, placing them near the upper end of the species’ typical lifespan.

Baby Chimpanzees Develop Distinct Regional Accents, Study Finds

Belen Perez Hernando, the sanctuary’s veterinarian, emphasized that “the health checks are a vital part of caring for these chimpanzees who have been through so much.” “The health checks are a vital part of caring for these chimpanzees who have been through so much,” — Belen Perez Hernando

Chimpanzees used for vaccine research get health checks as part of long-term care

Dr. Mark Ofua, a veterinarian and West Africa representative for the Wild Africa conservation group, used the chimps’ histories to illustrate broader animal-research concerns. “They were used in very invasive research … (and) went through a lot of experiments and pain,” — Liliana Pacheco Ricote, director of the sanctuary

Chimpanzees used for vaccine research get health checks as part of long-term care

The chimpanzees are classified as critically endangered, with rapidly declining numbers across West Africa. Providing systematic health monitoring not only improves individual welfare but also generates data that could inform conservation strategies for wild populations. Moreover, the public health-check initiative highlights ongoing debates about the ethical treatment of non-human primates in biomedical research and may influence future policy discussions on animal experimentation standards.

Chimpanzees used for vaccine research get health checks as part of long-term care

Humane World for Animals plans to extend the comprehensive health-check program to the remaining former research chimpanzees still residing at the refuge. Ongoing analysis of the medical data will be used to refine individualized care plans as the animals age, and the sanctuary intends to share findings with the broader primate-conservation community.

Chimpanzees used for vaccine research get health checks as part of long-term care