Blood donation is a vital act that saves thousands of lives every day. Yet, behind this act of solidarity sometimes lies an invisible risk: the transmission of so-called occult hepatitis B, which is difficult to detect with routine tests.

A recent study conducted by the Virology Department of the Pasteur Center in Cameroon, in collaboration with the blood bank of the Yaoundé Central Hospital, highlights a major public health and transfusion safety issue.

What is occult hepatitis B?

Unlike classic hepatitis B, occult infection is characterized by:
standard tests being negative (HBsAg negative), but the presence of the virus in very small amounts in the blood.
These donors appear healthy, but can still transmit the virus during a transfusion, particularly to vulnerable patients.

Main results of the study

The study, conducted between February and June 2025 with 269 blood donors in Yaoundé, reveals that:
62% of donors had markers of previous contact with the hepatitis B virus; in 3.3% of donors, the virus was still detectable using highly sensitive molecular techniques; two genotypes of the virus, A and E, are currently circulating in the studied population. These results confirm the existence of a residual risk of transmission, even when conventional tests are negative. A challenge for blood banks The detection of this “hidden” virus requires advanced molecular tests, which are effective but expensive and not easily accessible in many resource-limited settings. Systematically excluding all donors carrying hepatitis B antibodies would drastically reduce the number of available donations, thus worsening the already critical blood shortage in the country.

Vaccination: a sustainable and affordable solution In light of these constraints, researchers emphasize that the most effective, realistic, and economically feasible strategy remains systematic and mandatory vaccination against hepatitis B. This approach would: provide lasting protection for both donors and recipients, reduce the risk of transfusion, and strengthen trust in the healthcare system.

A collective issue This study reminds us that transfusion safety does not rely solely on technology, but also on strong prevention policies, ongoing awareness, and a collective commitment to vaccination.