Papers

Immunisation of infants at risk of perinatal transmission of hepatitis B: retrospective audit of vaccine uptake

Diane E Wallis, senior registrar in public health medicine, ^a Elizabeth H Boxall, consultant clinical scientist. ^b

^a Walsall Health Authority, Lichfield House, Walsall WS1 1TE, ^b Public Health Laboratory, Birmingham Heartlands Hospital, Birmingham B9 5SS

Correspondence to: Dr Boxall eboxall{at}rvl.globalnet.co.uk

Perinatal transmission of hepatitis B virus is the infection of infants at birth by mothers who are positive for hepatitis B surface antigen.¹ Around 85% of babies born to mothers who are also positive for hepatitis B e antigen become infected.²

Immunoprophylaxis initiated shortly after birththat is, after exposure to the viruscan prevent perinatal transmission. Passive prophylaxis with hepatitis B immunoglobulin is 50-90% efficacious, active prophylaxis with hepatitis B vaccine is 75-90% efficacious, and combined active and passive prophylaxis is >90% efficacious.²

Antenatal screening for hepatitis B surface antigen is universal in the West Midlands. The vaccination schedule for all babies of mothers with hepatitis B virus is 0 (within 48 hours of birth), 1, 2, and 12 months. Babies of mothers positive for hepatitis B e antigen are given 200 IU of hepatitis B immunoglobulin at birth as additional protection. Blood samples are taken at 12 months to monitor the effectiveness of vaccination, to audit uptake, and to identify children who have become carriers.

We carried out a retrospective audit on the six maternity units serving Birmingham to establish vaccine uptake and identify problems associated with compliance.

	Subjects, methods, and results

Top Subjects, methods, and results Comment References

We assessed immunoprophylaxis uptake by searching hospital records of all babies born in a 2 year period to mothers who were carriers of hepatitis B virus. Doctors were asked for details of any subsequent hepatitis B and childhood vaccinations in the infants through a postal survey with three mailings, and 116/130 (89%) doctors responded.

The table shows immunoglobulin and vaccine uptake according to maternal hepatitis B e antigen status. Twenty (15%) of the mothers were positive for hepatitis B e antigen. Six infants did not receive immunoglobulin: four were born to mothers positive for hepatitis B e antigen and two to mothers of unknown status for this antigen. Immunoglobulin was given late in two cases and in error in three.

Overall, 128 babies (99%) received a first dose of vaccine. Two babies admitted to a special care baby unit were not vaccinated. Three doses of vaccine were given to 66% (86) of babies, but by 12 months only 36 babies (28%) were vaccinated within the accepted time limit. A 0, 1, and 6 month schedule was followed in half of the cases.

Infants were more likely to undergo serological testing (total=28; 22%) if the mother was positive for hepatitis B e antigen. Two infants were positive for hepatitis B surface antigen and hepatitis B e antigen; one, whose mother was positive for hepatitis B e antigen, was given immunoglobulin, the other's mother was positive for hepatitis B e antibody.

Doctors' data showed a lower uptake for hepatitis B vaccination (86/113; 76%) than for routine childhood vaccinations (101/113; 90%). Of those children whose mothers had the same doctor, 56/85 (66%) completed their vaccination schedule compared with 29/85 (34%) where the doctor had changed (P=0.008, ²); 76/130 (58%) mothers had the same doctor as that listed in the hospital notes. Family size, social class, language, and ethnic origin were not associated with non-completion of hepatitis B vaccination.

	Comment

Top Subjects, methods, and results Comment References

We found that the impression of low uptake of hepatitis B vaccination as judged by serological testing at 12 months (22%) was inaccurate; 66% of babies received three doses of vaccine. Fewer infants completed hepatitis B vaccination than routine immunisations, suggesting a fault in delivering the service rather than parental reluctance.

As retrospective data collection is unsatisfactory, there is a need for childhood vaccination with hepatitis B to be registered on databases to generate appointments and audit uptake. This should be in place now that universal antenatal screening for hepatitis B surface antigen has been recommended.³

	Acknowledgments

   Contributors: DEW designed the audit, collected and analysed the data, and participated in writing the paper with EHB. EHB provided DEW with the list of subjects to be investigated, discussed core ideas, and participated in writing the paper; she maintains the database of mothers who are hepatitis B positive and advises on appropriate immunisations. EHB will act as guarantor for the paper.

	Footnotes

Competing interests: None declared.

	References

Top Subjects, methods, and results Comment References

1. Stevens CE, Beasley RP, Tsui J, Lee WC. Vertical transmission of hepatitis B antigen in Taiwan. N Engl J Med 1975; 292: 771-774[Abstract].
2. Boxall EH. Zuckerman A, ed. Prevention of hepatitis B in the newborn, children and adolescent. London: Royal College of Physicians , 1996.
3. Department of Health. Screening of pregnant women for hepatitis B and immunisation of babies at risk, 1998. (HSC 1998/127.)