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Immunity to hepatitis B among health care workers performing exposure prone procedures

BMJ 1994; 309 doi: https://doi.org/10.1136/bmj.309.6947.94a (Published 09 July 1994) Cite this as: BMJ 1994;309:94
  1. C J M Poole, consultant occupational physiciana,
  2. S Miller, director of occupational healtha,
  3. G Fillingham, senior occupational health nurse Occupational Health Service, Hammersmith Hospital, London W12 0HSa
  1. Occupational Health Service, Dudley Health Authority, Central Clinic, Dudley DY2 7BX
  1. Correspondence to: Dr Poole.
  • Accepted 28 March 1994

All health care staff who have contact with blood or bloodstained body fluids should be vaccinated against hepatitis B.1 More recent recommendations are that all surgeons should be immunised against hepatitis B by mid-1994 and all staff involved in exposure prone procedures by mid-1995,2 exposure prone procedures being those in which injury to the employee could result in exposure of a patient's open tissues to the employee's blood. We examined the immunity of staff of two health authorities and estimated the risk of a health care worker who performs exposure prone procedures being an infectious carrier of hepatitis B.

Subjects, methods, and results

Dudley Health Authority and Hammersmith and Queen Charlotte's Special Health Authority separately introduced policies before and in keeping with the government's guidelines2 in 1993 and 1991 respectively. All employees performing exposure prone procedures were asked to provide evidence of immunity to hepatitis B. Those without such evidence were asked to undergo testing for hepatitis B surface antigen and, if positive, for e markers.

Those with a titre of hepatitis B surface antibody >100 mIU/ml were recorded as being immune. Those with a titre of 10-100 mIU/ml were given a booster dose (20 µg) of hepatitis B vaccine (Engerix B), and their antibody response was measured two months later. Those with a titre <10 mIU/ml were given another course (at 0, 1, and 6 months) of vaccine, or the alternative recombinant hepatitis B vaccine (H-B-Vax II) if they had already had two courses.

The table shows immunity to hepatitis B in staff in the two health authorities. In Dudley two consultant surgeons refused to provide evidence of immunity or to undergo testing for hepatitis B surface antigen or core antibodies. The mean number of doses of vaccine given was 3.7, with most people developing adequate immunity after three; four surgeons, however, required either six or nine doses of vaccine. In London no employee refused to provide evidence of immunity or to undergo testing for hepatitis B surface antigen when appropriate. Four out of 230 employees (1.7%) who performed exposure prone procedures were positive for hepatitis B surface antigen; one of them, a surgeon, was also positive for the e antigen. Of these four, one was a doctor and three were midwives; three were born outside the United Kingdom.

Percentages (proportions) of employees who were immune to hepatitis B in Dudley Health Authority and Hammersmith and Queen Charlotte's Special Health Authority

View this table:

Comment

An immunity to hepatitis B of 94% among consultant surgeons in Dudley is encouraging. This figure is greater than published seroconversion rates of about 85% in normal adults because some of the staff had had up to three courses (nine injections) of vaccine. In fact, no doctor who was negative for hepatitis B surface antigen or naturally immune failed to respond to vaccine. This observation challenges the notion that 1-4% of those vaccinated will fail to respond to one or more courses of vaccine3 and supports the concept of slow responders.

Some people will not mount an immune response on vaccination because they are long term carriers of the virus; this applied to 1.7% of health care workers who performed exposure prone procedures in the London authority, but it applies to up to 11% of health care workers in parts of the world where hepatitis B is endemic.4 A prevalence of 1.7% is higher than that found in blood donors and at antenatal screening but in keeping with a mixed ethnic group of employees in a high risk occupation.5 For personal reasons a few employees will refuse to be vaccinated or provide evidence of immunity, but the government recommends that these staff are restricted in the same way as staff positive for hepatitis B e antigen.1 This number can be limited by counselling about the different types of hepatitis B serological markers and by reassuring staff that testing for the surface antigen will be done only with informed consent.

Few domestic staff and porters were immune, which is disappointing because needlestick injuries are regularly reported by them. The provision of occupational health services to NHS staff is, however, patchy, and the amount of budget allocated to the purchase of vaccines is controlled. The ability of occupational health departments to achieve the targets set by the NHS Executive will largely depend on their resources.

References

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View Abstract