HBsAg prevalence ‘unexpectedly’ higher in young Chinese blood donors
medwireNews: Despite universal hepatitis B virus (HBV) vaccination in China, the prevalence of hepatitis B surface antigen (HBsAg) is higher among young, presumably vaccinated, blood donors than older, potentially unvaccinated donors, find researchers.
They suggest that blood safety may be improved by providing an HBV vaccine boost for adolescents aged 15–17 years old, prior to reaching blood donor age.
“A powerful clinical trial comparing the incidence of HBsAg and [hepatitis B core antibodies] in young adults having received or not a vaccine boost around age 14 years would be highly informative,” the team writes in BMC Infectious Diseases.
Among 569,145 candidate blood donors who underwent HBsAg screening by dipstick rapid tests and enzyme immunoassays between 2005 and 2014 at the Shenzhen blood center, the overall HBsAg prevalence was 2.32%, with rates of 2.86%, 1.76%, and 2.77% in 2005, 2010, and 2014, respectively.
Male and first-time donors were significantly more likely to be positive for HBsAg than female and repeat donors, respectively (p=0.0001 and p<0.0001, respectively).
The HBsAg prevalence also varied significantly by age (p<0.001), with the highest prevalence observed among the youngest donors aged 18–25 years, at 2.73%, and the lowest among those aged 46 years or older, at 1.71%, “unexpectedly suggesting that younger donors [remain] at risk of chronic HBV infection,” say the study authors.
Furthermore, the prevalence of HBsAg was also significantly higher among first-time donors, aged 18–22 years, who were born in 1992 or thereafter, and presumed to have been vaccinated, than first-time donors in the same age bracket who were born before implementation of universal vaccination and presumed not to be protected (3.89 vs 3.51%, p=0.005).
Describing the finding as “surprising,” Chengyao Li (Southern Medical University, Guangzhou, China) and fellow investigators surmise that the differences could be “explained by the slow and progressive increase in vaccination compliance in the Guangdong province,” from 30% in 1992 to 76% in 2005, stabilizing at 96% in 2005.
“The same study conducted in blood donors born after 2002 when compliance reached over 90% might better reflect the impact of HBV vaccination on the safety of the blood supply,” they conclude.
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