[Abstract] To define an optimal dosage and vaccination schedule of a new Chinese inactivated hepatitis A (HA) vaccine, 206 healthy children in mountain area villages of Hebei Province aged 5-15, negative for anti- HAV antibody were choose and were randomly divided into 6 groups. They were given 500U/does and 250U/does of vaccine by 0,1、0,3 and 0,5 month schedules. The local and systemic site effects were examined after primary and booster doses. The seroconversion rate and the geometric mean titer of anti-HA antibody were tested at 2,3,4 weeks and 3,4,6,7 months after vaccination. It showed that mild local and systemic reactions appeared transiently after vaccination. The positive seroconversion rates were 97.4% and 97.0% at 2 weeks after primary isosulation for 500U/dose and 250U/dose, respectively. Geometric mean antibody titers of 250U/dose ware 1 973mIU/ml, 3 265mIU/ml and 5 963mIU/ml are 0,1、0,3 and 0,6 month groups, respectively, among which, the 0,5 mouth groups developed the highest geometric mean antibody titer which had significant difference statistically. We concluded that the Chinese new inactivated hepatitis A vaccine is safe and effective, the 0.1 month schedule can be applied to special persons (such as travelers and workers to HAV prevalent area) and the 250U/dose with 0,6 month schedule is the optimal dosage and vaccination schedule for children.
[Author] Ren Yinhai, Wu Wenting, Zhang Yucheng, et al
[key words] Inactivated hepatitis A vaccine; Immunogenicity; Safety; Dosage; Vaccination schedule
The previous research has proved that Healive inactivated hepatitis A (HA) vaccine 1000U~5000U has the characteristics of high immunogenicity, safety, high antibody seroconversion rate and high GMT, which is further proved by research among adults, children and the children seropositive to hepatitis B (HB) viral surface antigen (HBsAg). It has also proved that further research on the dose for children using 500U/dose is necessary. Therefore we observed the immune effects of different immune schedules by decreasing the dose (250U) of inactivated hepatitis A vaccine. Our report is as follows:
Materials and Methods
1. Vaccine Healive inactivated hepatitis A vaccine, produced by Sinovac, consists of viral antigen 500U/a and 250U/a, with the batch Nos. 20010212 and 20010211 respectively.
2. Vaccinated object Healthy children were chosen from the villages with similar economic levels, sanitary conditions and living habits in some mountainous area. These children were aged 5~15 seronegative to anti-hepatitis A viral antibody (anti-HAV) with normal serum alanine aminotransferases (ALT) and normal functions of hearts, lungs, livers and spleens, and had no anaphylactic experience before. Thus 206 children susceptible to HA virus were chosen and divided into groups randomly by unit of village. In the control groups, the immune effects of different doses and immune schedules were observed. Boys and girls were in the ratio of 1:1.07 and averagely aged 7.1.
3. Vaccination method and schedule It used the upper arm deltoid muscle injection with 0-1, 0-3 and 0-12 immune schedules.
4. By-reaction observation The local reactions (red, turgid, hot and ache) and the systematic reactions (hot, tire, headache, dizzy, nausea, inappetence and tetter) were observed at 30min and 8, 24, 48, 72h after immunization.
5. Serology test Venous blood 3ml was sampled on an empty stomach each time, and blood serum was separated aseptically and stored for test under –20°C. The anti-HAV standard crystal for test, the freeze-dry crystal, was provided by WHO with the batch No. 011107, which was dissolved in distilled water by 1amp./1.0ml with anti-HAV content 98.6IU/ml.
5.1 Anti-HAV seroconversion rate test The enzyme linked immunosorbent assay (ELISA) was used in the test, and the reagent boxes were purchased from Abbott company with the batch No. 80450M200, and the sensibility was 22mIU/ml; and the sample competition restrain rate > 50% was recorded as anti-HAV positive.
5.2 Anti-HAV GMT test The standard anti-HAV reagent was used in the test with the batch No. 011220 and the sensibility was 103mIU/ml. The direct-line regression statistics was made according to standard antibody GMT logarithm and OD value within the properly dilute limit in order to obtain the regression formula. Concurrently, corresponding antibody GMT (mIU/ml) was calculated by OD value of the measured blood serum sample. The standard crystal was diluted multiply to 5 dilute degrees of 500mIU/ml, 250mIU/ml, 125mIU/ml, 62.5mIU/ml and 32.25mIU/ml. At least three pinholes were tested and for each dilute degree, and at least three continuous dilute degrees were within a direct-line limit. According to actual antibody dilute degree (the lowest dilute degree and the original liquid in the ratios of 1:2 and 1:4), the sample, along with the OD value of the standard crystal, was substituted in the regression formula to calculate antibody mIU/ml within the direct-line limit of the standard crystal OD value. The anti-HAV GMT value calculated by this method was consistent with Abbott reagent.
5.3 Liver function examine ALT test used Laishi method, for which £ 40U was normal. The reagent boxes were produced by Beijing BHKT Clinical Reagent Co., Ltd with the batch No. 010622.
6. Method of statistical analysis The SAS system process was used for statistics. Anti-HAV seroconversion rate comparison was examined by c2; anti-HAV GMT was shown by mIU/ml; and the comparison between two control groups was examined by t.
Results
1. Safety
By-reactions did not occur immediately after immunization, which occurred in 8~24h afterwards and disappeared in 48h. The local by-reactions were red and turgid (with dia. 1mm~4mm, and ³5mm was regarded as positive), and the systematic by-reactions were slight hot, and neither body temperature > 37.5°C nor ALT abnormal occurred(See Table 1).
Table 1 By-reaction Rate Comparison of Different Dose Groups after Immunization of Inactivated Hepatitis A Vaccine
| Group |
After the 1st immunization |
After the 2nd immunization |
| No. of people |
Local reactions |
Systematic reactions(%) |
No. of people |
Local reactions |
Systematic reactions (%) |
| 500U |
106 |
0 |
5 (4.7) |
106 |
0 |
2 (1.9) |
| 250U |
100 |
0 |
4 (4.0) |
100 |
0 |
2 (2.0) |
2. Antibody reactions at 2, 3 and 4 weeks after Primary Immunization of Inactivated Hepatitis A Vaccine
By the 2nd weeks after the primary immunization, 250U/a group and 500U/a group respectively had anti-HAV seroconversion rates of 97.0% and 97.4%, and GMTs of 355mIU/ml and 371mIU/ml; and by the 3rd and 4th weeks, the anti-HAV seroconversion rates and the anti-HAV GMTs were similar to those bythe 2nd week. The immunogenicity was satisfying (See Table 2).
Table 2 Antibody Seroconversion Rate and Antibody GMT Comporison of Different Doses and Schedules after Immunization of Inactivated Hepatitis A Vaccine
| Group |
The 2nd week after immunization |
The 3rd week after immunization |
|
| No. of people |
No. of Seroconversion |
Seroconversion rate (%) |
GMT (mIU/ml) |
No. of people |
No. of Seroconversion |
Seroconversion rate (%) |
GMT (mIU/ml) |
No. of people |
No. of Seroconversion |
Seroconversion rate (%) |
GMT (mIU/ml) |
| 00U |
39 |
38 |
97.4 |
371 |
49 |
49 |
100 |
320 |
70 |
69 |
98.6 |
321 |
| 50U |
33 |
32 |
97.0 |
355 |
38 |
36 |
94.7 |
195 |
67 |
64 |
95.5 |
251 |
t=1.996, P<0.05; t=1.989, P>0.05; t=1.978, P>0.05;
3. Antibody reactions after through immunization of inactivated hepatitis A vaccine
500U group and 250U group respectively tested 106 people and 100 people, and tested in six groups of 0-6, 0-3, 0-1month schedules. By one month after the through immunization, all control groups had antibody seroconversion rates 100%, and 500U group had higher anti-HAV GMT than 250U group. 0-3 schedule 500U and 250U groups had different antibody GMT, which had statistical significance. But the dose difference shown in other schedule groups had little use in statistics (See Table 3).
Table 3 Anti-HAV Reactions after Through Immunization of Inactivated Hepatitis A Vaccine
| Immune schedule |
Dose (U/a) |
No. of people |
Anti-HAV seroconversion |
GMT (mIU/ml) |
95% confidence interval |
| No. of people |
% |
| 0-6months |
500 |
36 |
36 |
100.0 |
7154 |
9296-5502 |
| 250 |
33 |
33 |
100.0 |
5963 |
8283-4317 |
| 0-3months |
500 |
31 |
31 |
100.0 |
6611 |
9217-4742 |
| 250 |
34 |
34 |
100.0 |
3265 |
4433-2403 |
| 0-1month |
500 |
39 |
39 |
100.0 |
2800 |
3381-2319 |
| 250 |
33 |
33 |
100.0 |
1973 |
2757-1412 |
t0-6months (500U, 250U) =1.996, P>0.05; t0-3months (500U, 250U) =1.998, P<0.05; t0-1months (500U, 250U) =1.994, P>0.05.
4. Immunogenicity comparison of different doses of three immune schedule inactivated hepatitis A vaccines
After vaccinated by 0-1, 0-3, 0-6month immune schedules, in 500U/a and 250U/a dose groups, both seroconversion rates were 100%. However, the anti-HAV GMTs at 0-6month schedule were higher than at 0-3month and 0-1month schedules. The schedule GMT difference had statistical significance(See Table 4).
Table 4 Comparison of different schedule inactivated hepatitis A vaccines
| Vaccinated dose (U/a) |
Immune schedule (month) |
No. of people |
Anti-HAV seroconversion |
Anti-HAV GMT (mIU/ml) |
95% confidence interval |
| No. of people |
% |
| 500 |
0-6 |
36 |
36 |
100.0 |
7154 |
1 |
| 0-3 |
31 |
31 |
100.0 |
6611 |
1 |
| 0-1 |
39 |
39 |
100.0 |
2800 |
2 |
| 250 |
0-6 |
33 |
33 |
100.0 |
5963 |
1 |
| 0-3 |
34 |
34 |
100.0 |
3265 |
1 |
| 0-1 |
33 |
33 |
100.0 |
1973 |
2 |
T500U (0-6months, 0-3months, 0-1month) =1.997, P<0.01; t250U (0-6months, 0-3months, 0-1month) =1.997, P<0.05.
Discussion
HAV infection is the highest among 5 serum-type hepatitis virus infections in the world. China has a high hepatitis A infection rate where children are the largest susceptible group and the major vaccinated object to prevent hepatitis A. 10-year application has proved that the homemade attenuated active hepatitis A vaccine can produce protective antibody and reach a short-term protective rate 95%. However, its antibody seroconversion rate and GMT are low. Our research observed the different schedule effects of small dose Healive inactivated hepatitis A vaccine on children and proved again that small dose vaccine has excellent immunogenicity, slight by-reactions of the same safety as the international same type vaccine’s.
By the 2nd week after the primary immunization, 500U and 250U Healive hepatitis A vaccines had anti-HAV seroconversion rates 97.0% and 97.4% respectively, and GMTs of 355mIU/ml and 371mIU/ml, and could provide enough protection. Therefore the inactivated hepatitis A vaccine is applicable to emergency vaccination.
After the through immunization, the anti-HAV GMTs for 250U/0-1month schedule and 500U/0-1month schedule reached 1973mIU/ml and 2800mIU/ml respectively, therefore they are applicable to fasten immunization of tourists and working personnel in some HA epidemic area.
After the through immunization in different schedule groups, 500U and 250U groups reached the seroconversion rates 100%. Although GMT showed some dose effect relations, the 0-6month schedule was better than other schedules, therefore 250U/0-6month schedule is applicable to children.
(We hereby express our thanks to Kang Jianting, Li Haijun and Liu zhonglin who participated in part of our research.)
References
[1] By Liu Chongbai, Ren Yinhai, Zhang Yucheng, Research on the Safety Immunogenicity and Vaccination Schedules of Homemade Inactivated Hepatitis A Vaccine Application on Children [J], 1-3, 8(1), 2002 Chinese Journal of Vaccines and Immunization
[2] By Ren Aiguo, Ma Junrong, Feng Fumin, Research on the Safety and Immunogenicity of Homemade Inactivated Hepatitis A Vaccines [J], 357-359, 15(4) 2001 Chinese Journal of Experimental and Clinical Virology
[3] By Ren Yinhai, Zhang Yucheng, Wu Wenting, Research on the Safety and Immunogenicity of Homemade Inactivated Hepatitis A Vaccine Application on Little Children [J], 209-211, 3(3) 2002 China Preventive Medicine Magazine.
[4] By Chen Jiangting, Ren Yinghai, Wu Wenting, Observation on the Immunogenicity and Safety of Inactivated Hepatitis A Vaccine on HBsAg Positive Children [J], 370-371, 16(4) 2002 Chinese Journal of preventive medicine
[5] By Dai Zhicheng, Qi Guoming, Survey on Chinese Virus Hepatitis Serum Epidemics (Volume I) [M], 21-35 1997 Beijing Scientific and Technical Publishing House
[6] By Dong Meixiang, Cao Yiyun, Development Research on attenuated active hepatitis A vaccine (H2) [J], 178-181 7(3) 2001 Chinese Journal of Vaccines and Immunization
Original: Chinese J of Vaccines and Immunization Apr.2003 Vol.9 No.2
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