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HEPATITIS VACCINATION POLICY FOR HOSPITAL STAFF
1272
STABILITY OF HUMAN DIPLOID CELL RABIES VACCINES
SIR,-The article by Dr Nicholson and colleagues (April 23, p 1 916) is really useful for countries where rabies is a major problem. We too have studied the stability of human diploid cell rabies vaccines (HDCV, Institut Merieux) by measuring antibody responses. Lot V0505 (expiration date May, 1983) of HDCV was kept in the US Centers for Disease Control refugee office in Bangkok. Before Sept. 17, 1982, the vaccine had been stored at between 0 and 9 °C, but on Sept 17 the electricity supply was cut off and the vaccine was at8-19°C for 20 h. The stability of this vaccine was compared with that of lot W0527 (expiration date June, 1984) which was in cold storage. Five vaccines from each lot were given as booster vaccination and sera were collected on days 0, 7, 14, and 28. For primary immunisation, vaccines from each lot were given to five volunteers on days 0, 7, and 28, and sera were collected on day 0, 7, 14, 28, and 56. Antibody responses were determined by the standard mouse neutralisation test.2 Neutralising antibody (titres) are
TABLE I-HEPATITIS B SEROLOGICAL MARKERS AMONGST HOSPITAL
PERSONNEL IN A GENERAL HOSPITAL IN SINGAPORE
TABLE 11-HBV SEROLOGICAL MARKERS IN HOSPITAL PERSONNEL AND
NORMAL ADULT POPULATION, WITH MEAN AGES I
summarised in the table. AND BOOSTER v0505 AND w0527
NEUTRALISING ANTIBODIES AFTER PRIMARY VACCINATION WITH HDCV LOTS I
I
HBV
serological markers were more common amongst paediatric, renal, laboratory, surgical (including dental), and ward orderly staff. New entrants (medical students, nurses, and house officers) were J
*One subject omitted because her titre 95, and 95 IU/ml respectively. ND=not done
I on
I
I
day 0 was 33 IU/ml with subsequent titres of 60,
The condition of HDCV kept at 8-19°C for 20 h was still good, though lot V0505 gave deep pink colour after reconstitution and produced more local and systemic reactions on the day of vaccination than did lot W0527. The reconstituted HDCV was stable: fifteen primary vaccines who had intradermal injections of 01 ml HDCV, reconstituted and stored in a refrigerator for weeks, on day 0, 3, 7 had neutralising antibody titres in the range 1 - 7-55 IU/ml on days 14-30 (G. Harverson, personal communication). Department of Microbiology, Faculty of Medicine, Mahidol University, Siriraj Hospital, Bangkok 10700, Thailand
CHANTAPONG WASI PARAMET CHAIPRASITHIKUL PRASERT THONGCHAROEN
HEPATITIS VACCINATION POLICY FOR HOSPITAL STAFF
SIR,-In endemic regions a large proportion of the population will have had subclinical HBV infections and will not require hepatitis B vaccination. However, from time to time, acute HBV outbreaks occur in high risk areas (eg, among hospital staff). To determine which hospital staff and what areas were more prone to HBV infections we investigated the immune status of these staff. Sera were tested for HBsAg, anti-HBc, and anti-HBs (enzyme-linked immunoassay) (Abbott) which in our laboratory has the same sensitivity as the solid phase radioimmunoassay. Out of 524 personner screened in a major teaching and general hospital, 33% were positive for all HBV markers and 30% had antiHBs (table I). These figures were no higher than those for the general outside male (55%) and female population (43%) (table n).
vulnerable since many were in their early 20s and almost 80% had not been exposed to HBV. 47% of those who had been in the hospital environment for more than 3 years had HBV positive markers as compared with 9% of those with less than 1 year’s service and 22% of those with 1 to 3 years’ service. In an earlier study we found subclinical asymptomatic HBV infections in 28% of newly admitted children, and the prevalence of HBsAg was 11% in these children. In the hospital’study most staff members had no history of acute infection, suggesting that subclinical infection is a common mode of transmission. This study includes follow-ups and a few seronegative people have become positive for HBsAg asymptomatically. The prevalence of HBV carriers in Singapore is 8%, with an estimated 200 000 symptomless carriers. Most infections occur horizontally, and vertical transmission contributes to about 900 new cases each year. By the age of 60 years nearly 90% of the population have been subclinically infected. The aim of any hepatitis B vaccination programme is to prevent the short and long term consequences of HBV infection. In Singapore and in many other South-East Asian and Western Pacific countries,2HBV infection is a major public health problem. In these areas, HBV infections are responsible for chronic hepatitis, aggressive cirrhosis, and primary hepatocellular carcinoma (now a major cancer in Singapore).
’Selective immunisation3of at-risk groups would include the high risk hospital personnel (especially young staff). Pre-vaccination screening for HBsAg and anti-HBs has now been started amongst staff entering or working in high risk parts of the hospital. WHO Research and Reference Centre for
University Department of Medicine I, National University of Singapore, Singapore General Hospital, Singapore
606-11. P
2 Atanasiu
Quantitative assay and potency test of antirabies serum and immunoglobulin. In. Kaplan M, Koprowski H, ed. Laboratory techniques in rabies, 3rd ed. Geneva: World Health Organisation, 1973: 314-18.
C. J. OON LILY CHAN R. GUAN
SH, Singh R, Oon CJ, Wong HB. A cross sectional study of hepatitis B immune Asian children in Singapore. Ann Trop Pediatr 1982, 2: 53-56 2 World Health Organisation. Report of a Scientific Group on Viral Hepatitis B and its Related Diseases (Nagasaki, Japan, Sept 29 to Oct 2, 1982. 3. Oon CJ, Lily Chan, Chan SH, Goh CN, Goh KT, Ong YW, Tan KL. Quack SK Immune status of at-risk populations in Singapore to the hepatitis B virus In Proceedings of second International Association of Biological Standards conference on Standardisation in Immunoprophylaxis of Hepatitis Virus Infection (Athens, 1982) (In press). 1. Quack
status in
1. Thongcharoen P, Wasi C, Chavanich L. Rabies in Thailand. In: Mackenzie J, ed. Viral diseases in South-East Asia and the Western Pacific. Sydney: Academic Press, 1982:
Hepatitis,
STABILITY OF HUMAN DIPLOID CELL RABIES VACCINES
SIR,-The article by Dr Nicholson and colleagues (April 23, p 1 916) is really useful for countries where rabies is a major problem. We too have studied the stability of human diploid cell rabies vaccines (HDCV, Institut Merieux) by measuring antibody responses. Lot V0505 (expiration date May, 1983) of HDCV was kept in the US Centers for Disease Control refugee office in Bangkok. Before Sept. 17, 1982, the vaccine had been stored at between 0 and 9 °C, but on Sept 17 the electricity supply was cut off and the vaccine was at8-19°C for 20 h. The stability of this vaccine was compared with that of lot W0527 (expiration date June, 1984) which was in cold storage. Five vaccines from each lot were given as booster vaccination and sera were collected on days 0, 7, 14, and 28. For primary immunisation, vaccines from each lot were given to five volunteers on days 0, 7, and 28, and sera were collected on day 0, 7, 14, 28, and 56. Antibody responses were determined by the standard mouse neutralisation test.2 Neutralising antibody (titres) are
TABLE I-HEPATITIS B SEROLOGICAL MARKERS AMONGST HOSPITAL
PERSONNEL IN A GENERAL HOSPITAL IN SINGAPORE
TABLE 11-HBV SEROLOGICAL MARKERS IN HOSPITAL PERSONNEL AND
NORMAL ADULT POPULATION, WITH MEAN AGES I
summarised in the table. AND BOOSTER v0505 AND w0527
NEUTRALISING ANTIBODIES AFTER PRIMARY VACCINATION WITH HDCV LOTS I
I
HBV
serological markers were more common amongst paediatric, renal, laboratory, surgical (including dental), and ward orderly staff. New entrants (medical students, nurses, and house officers) were J
*One subject omitted because her titre 95, and 95 IU/ml respectively. ND=not done
I on
I
I
day 0 was 33 IU/ml with subsequent titres of 60,
The condition of HDCV kept at 8-19°C for 20 h was still good, though lot V0505 gave deep pink colour after reconstitution and produced more local and systemic reactions on the day of vaccination than did lot W0527. The reconstituted HDCV was stable: fifteen primary vaccines who had intradermal injections of 01 ml HDCV, reconstituted and stored in a refrigerator for weeks, on day 0, 3, 7 had neutralising antibody titres in the range 1 - 7-55 IU/ml on days 14-30 (G. Harverson, personal communication). Department of Microbiology, Faculty of Medicine, Mahidol University, Siriraj Hospital, Bangkok 10700, Thailand
CHANTAPONG WASI PARAMET CHAIPRASITHIKUL PRASERT THONGCHAROEN
HEPATITIS VACCINATION POLICY FOR HOSPITAL STAFF
SIR,-In endemic regions a large proportion of the population will have had subclinical HBV infections and will not require hepatitis B vaccination. However, from time to time, acute HBV outbreaks occur in high risk areas (eg, among hospital staff). To determine which hospital staff and what areas were more prone to HBV infections we investigated the immune status of these staff. Sera were tested for HBsAg, anti-HBc, and anti-HBs (enzyme-linked immunoassay) (Abbott) which in our laboratory has the same sensitivity as the solid phase radioimmunoassay. Out of 524 personner screened in a major teaching and general hospital, 33% were positive for all HBV markers and 30% had antiHBs (table I). These figures were no higher than those for the general outside male (55%) and female population (43%) (table n).
vulnerable since many were in their early 20s and almost 80% had not been exposed to HBV. 47% of those who had been in the hospital environment for more than 3 years had HBV positive markers as compared with 9% of those with less than 1 year’s service and 22% of those with 1 to 3 years’ service. In an earlier study we found subclinical asymptomatic HBV infections in 28% of newly admitted children, and the prevalence of HBsAg was 11% in these children. In the hospital’study most staff members had no history of acute infection, suggesting that subclinical infection is a common mode of transmission. This study includes follow-ups and a few seronegative people have become positive for HBsAg asymptomatically. The prevalence of HBV carriers in Singapore is 8%, with an estimated 200 000 symptomless carriers. Most infections occur horizontally, and vertical transmission contributes to about 900 new cases each year. By the age of 60 years nearly 90% of the population have been subclinically infected. The aim of any hepatitis B vaccination programme is to prevent the short and long term consequences of HBV infection. In Singapore and in many other South-East Asian and Western Pacific countries,2HBV infection is a major public health problem. In these areas, HBV infections are responsible for chronic hepatitis, aggressive cirrhosis, and primary hepatocellular carcinoma (now a major cancer in Singapore).
’Selective immunisation3of at-risk groups would include the high risk hospital personnel (especially young staff). Pre-vaccination screening for HBsAg and anti-HBs has now been started amongst staff entering or working in high risk parts of the hospital. WHO Research and Reference Centre for
University Department of Medicine I, National University of Singapore, Singapore General Hospital, Singapore
606-11. P
2 Atanasiu
Quantitative assay and potency test of antirabies serum and immunoglobulin. In. Kaplan M, Koprowski H, ed. Laboratory techniques in rabies, 3rd ed. Geneva: World Health Organisation, 1973: 314-18.
C. J. OON LILY CHAN R. GUAN
SH, Singh R, Oon CJ, Wong HB. A cross sectional study of hepatitis B immune Asian children in Singapore. Ann Trop Pediatr 1982, 2: 53-56 2 World Health Organisation. Report of a Scientific Group on Viral Hepatitis B and its Related Diseases (Nagasaki, Japan, Sept 29 to Oct 2, 1982. 3. Oon CJ, Lily Chan, Chan SH, Goh CN, Goh KT, Ong YW, Tan KL. Quack SK Immune status of at-risk populations in Singapore to the hepatitis B virus In Proceedings of second International Association of Biological Standards conference on Standardisation in Immunoprophylaxis of Hepatitis Virus Infection (Athens, 1982) (In press). 1. Quack
status in
1. Thongcharoen P, Wasi C, Chavanich L. Rabies in Thailand. In: Mackenzie J, ed. Viral diseases in South-East Asia and the Western Pacific. Sydney: Academic Press, 1982:
Hepatitis,