In the present population-based study, we found that, although most children of HBV carrier mothers were protected against chronic HBV infection after the introduction of the universal immunization, there were considerable gaps in the immunoprophylaxis of perinatal HBV infection between the routine practices and national recommendations in China. Such gaps may also exist in other developing countries since only 23.7% of the 8–10-year-old children in East Java, Indonesia, were anti-HBs positive after introduction of universal vaccination program [17
] and the vaccine coverage in remaining quilombo communities in Central Brazil is suboptimal [18
]. Therefore, the significance of full compliance with the recommended procedures to prevent perinatal HBV transmission should be emphasized in China as well as other developing countries.
Prenatal HBsAg screening has been recommended in all pregnant women in China since the late of 1980s, however, the actual screening rate in the present investigation was only 52.3%, far from the rates of 90–99% in developed countries [19
]. The gap is particularly substantial in the rural areas as only 46.9% of pregnant women underwent the prenatal screening. Since all investigated women had experienced prenatal examinations and delivered their children in hospitals, we considered that the low HBsAg screening rate was largely attributed to the health care providers’ unawareness of the importance of the screening. We can imagine that the adherence to preventive measures may be worse in infants of mothers delivering at home in remote rural areas of China. Thus, more intensive information about the importance of preventing mother-to-infant transmission of HBV should be provided to health care providers as well as pregnant women to increase prenatal HBsAg screening.
The administration of prophylactic measures against hepatitis B in HBV-exposed infants was far from optimal in China. Although all the infants received hepatitis B vaccine, the birth dose was delayed in 15.1% of the newborns and three doses were not completed in 7% of them. Furthermore, HBIG was used only in 37.6% of the high risk infants. The untimely use of the birth dose vaccine was apparently due to the oversight of the health care providers since it is recommended that the birth dose vaccine be given within 24
hours after birth. The low usage of HBIG might be caused by several reasons, first, unavailability of HBIG in some hospitals because these hospitals do not have specific policies on preventing perinatal HBV infection; second, the lack of knowledge on the standard prophylaxis in the health care providers; third, neglecting the use of HBIG by some health care providers since the implementation of universal vaccination against hepatitis B, whatever the status of the mother, might have been confusing for those not specialized in HBV infection; and fourth, also most important, unknown HBsAg status in the pregnant women before birth because of the low rate of prenatal HBsAg screening. Unlike the recommendation in USA, in which infants born to women with unknown HBsAg status are administered with both HBIG and hepatitis B vaccine [23
], the policy in China is that only infants born to known HBV carrier mothers receive passive-active immunoprophylaxis.
Although only 3.7% of HBV-exposed infants in this investigation were infected with HBV, our findings indicate that there is still a room to increase the protection conferred by the vaccination against hepatitis B, because the failure of the protection is largely due to the inappropriate administration of the recommended prophylactic procedures in the routine practices (Table ). Additionally, recent studies show that in developed countries, 98–100% of the HBV-exposed infants were protected against the chronic infection after passive-active immunoprophylaxis had been strictly followed [9
]. This highlights the importance of the full adherence to the standard immunoprophylaxis in the prevention of perinatal HBV infections.
There are some limitations in the present study. First, the overall follow-up rate (71.1%) in HBV-exposed children was not high. However, it is less likely that the HBsAg positive rate in the children was biased due to this reason, since a comparable follow-up rate (72%) in children born to HBeAg positive carrier mothers, whose infants are more prone to be infected, was achieved. Second, the perinatal HBV infection in this study was examined at the age of 5–7
years, rather than at 12
months old. However, spontaneous HBsAg loss in children perinatally infected is very low [24
], and novel HBV infection in vaccinated children rarely occurs [25
]. Thus, the positive rate of HBsAg in children at ages of 5–7
years whose mothers are infected with HBV may essentially represent the perinatal infection. Third, the measures in the routine practices investigated in this survey were implemented during 2002–2004 and not all the data on screening for HBsAg in pregnant women and administration of HBIG in infants were validated by medical records; the current status of services for infants of HBV carrier mothers could be improved. However, a recent preliminary survey in the prevention of perinatal HBV transmission among obstetric and gynecological medical staffs in China showed that there is insufficient training in the application of immunoprophylaxis, particularly in rural areas (unpublished data), suggesting there is a big room to improve the immunoprophylaxis against hepatitis B. On the other hand, there are two strengths in this study. One is that the study subjects were from 14 areas across Jiangsu; the data should be superior to those from a single center study. The other is that we conducted this study as the third party in a more objective manner.
Although the results in this study were derived from a province in China, we consider that the identified gaps also exist in most areas of China as Jiangsu is one of the six financially prosperous regions among the 31 provinces in Mainland China. We also consider that the data of the present study may basically reflect the scenario in some developing countries like China. Thus, a national organization dedicated to educating health care providers in delivery units and delivery hospitals about the knowledge of preventing perinatal HBV infection will be critical for filling the gaps.