Mackay Medical College yesterday said that research had shown that hepatitis B vaccinations given to infants can wear off as they grow up and may not provide full, lifetime protection.
In response to frequent questions from patients about whether hepatitis B vaccination of infants can guarantee lifetime immunity, Wang Li-yu (王豊裕), a professor at the college’s Institute of Biomedical Sciences, said that according to their long-term research, some immunized people may still be affected by the disease.
Hepatitis B is highly infectious and infants can be infected by their mothers even before birth or via blood during birth, he said, adding that the risk of these infants becoming hepatitis B carriers is relatively high if they do not receive vaccinations at birth.
Through 10 years of research tracking about 8,900 teenagers now in their senior year of high school, Wang’s research team found that if the mother is a hepatitis B carrier of HBeAg-positive or high-serum HBsAg, and the infant did not receive a hepatitis B immune globulin (HBIG) vaccination on the day of birth, the infant will have a 29 percent risk of becoming a hepatitis B carrier by senior-high school age.
The risk percentage drops to 19 percent if the infant received a HBIG injection on the day of birth, the team said.
Because the risks are still considered high, “it is suggested that pregnant mothers who are hepatitis B carriers let their new born child get a HBIG injection and receive the first shot of the hepatitis B vaccine on the day of birth,” Wang said.
Wang also suggested that these children be tested periodically for hepatitis B as they grow up, and receive treatment if the tests indicate hepatitis B infection.
Another study conducted by the team on about 2,000 children borne by hepatitis B carrier mothers, showed that one-sixth of them lost their immunity to hepatitis B by the time they reached senior-high school age, even though they all received vaccinations when they were infants.
Wang suggested that these teenagers should consider receiving additional hepatitis B vaccinations.