[Abstract] In order to evaluate the immunogenicity, safety and vaccination schedules of a new inactivated hepatitis A (HA) vaccine, 275 healthy children in mountain area villages of Hebei Province aged 5~15, negative both for HBsAg and anti-HAV antibody were randomly divided into 4 groups by village. They were given 1, 000 units (U)/dose and 500 units (U)/dose of vaccine by 0.3 and 0.6 month schedules. The local and systemic site effects were examined 30 min after vaccination and within 8h, 48h, 72h of vaccination respectively. The seroconversion rate and the geometric mean titer ( GMT) of anti-HA antibody were tested at months 1, 3, 4,6,7. The results showed that the local and systemic side effects of the new inactivated HA vaccine after first dose administration were 11.76% and 12.23% among children given 1, 000 U and 500 U groups were 938%, 9.6% and 174 miu/ml, 146 miu/ml respectively. One month after the second dose of vaccine, the positive seroconversion rates of all 4 groups were 100%, and the GMT raised to 7, 540 miu/ml in 1,000 U group and 4,535 miu/ml in 500 U group. The GMT in 500 U group with ,6 month schedule was more higher than that of 0,3 month schedule, 4,535 miu/ml versus 3.269 miu/ml the difference was statistically significant. We concluded that the new inactivated hepatitis A vaccine has good immunogenicity and safety, The 500 units/dose with 0,6 month schedule is better than 0,3 month schedule for children.
[Author] Liu Chong- bai, Ren Yin-hai, Zhang Yu-chen, et al
[key words] Inactivated Hepatitis A vaccine; Safety; Immunogenicty; Vaccination schedule
Hepatitis A keeps a high prevalence in China, especially for the children, at the morbidity of 45.5% and 72.9% for the children aged from 1 to 14 in urban and rural areas respectively [1], which reaches at the peak every 5-7 years [2]. The improvements of the living conditions and the hygiene conditions can decrease the infection rate and morbidity rate temporarily but cannot terminate its prevalence. In 1988, Shanghai occurred the Mass Epidemic of Hepatitis A. It is an essential measure that the children inoculate the safe and high-immunogenicity hepatitis A vaccine. We initially conducted the study on immunogenicity, safety and vaccination schedule of a domestic inactivated hepatitis A vaccine in Chinese children from September 1998 to April 1999 as the follows:
Materials and Methods
1 Vaccine: each dose of the laboratory hepatitis A inactive vaccine produced by Tangshan Yi’an Bioengineering Co., Ltd. contains viral antigen at 1000U and 500U, with the ratified number of 971201.
2 Vaccinated object: in the adjacent villages of a certain mountain area with similar economic level, hygiene condition and living habit, made use of the enzyme linked immunosorbent assay (ELISA) anti-HAV agent to choose the rural healthy and susceptible children aged 5-15 years old with negative anti-HAV, HBsAg, normal ALT, and normal functions of heart, lung, liver and spleen, without allergic history, totally 275 persons, who were divided into groups at random, taking the village as the unit, with the sex proportion of male and female at 1:1.07, and the average age of 7.1.
3 Vaccination method and schedule injection at the deltoid muscle of the upper arm, the first dose was taken as the primary immunization, and the second dose was injected was taken as the booster immunization at 3 or 6 months after the first dose (0.3 month or 0.6 month schedule).
4 Side effect investigation all the vaccinated objects will be investigated after 30 minutes of injection for the immediate reaction, and the local (red, swell, hot and pain) and systemic reactions (fever, hypodynamia, ache, dizzy, nausea, inappetence) will be investigated after 8, 24, 48 and 72 hours.
5 Serology test take the venous blood sample when the people is in empty stomach, 3ml each time, aseptically separating the serum, stored at –20℃ for test. The standard HAV antibody is provided by the WHO, as the lyophilisation crystal, with the ratified number of 990201, and 1.0ml distilled water should be filled to dissolve in each ampoule, with the concentration at 98.6IU/ml.
5.1 The seroconversion of HAV antibody test Adopt the ELISA Competitive Restriction Method, making use of ELISA agent provided by Abbott Company, with ratified number of 5477RM100, and the sensitivity is 23.8-47.5mIU/ml. If the competitive restriction rate of the sample is more than 50%, it will be taken as the positive HAV antibody.
5.2 HAV antibody level test Making use of the domestic standardized HAV antibody testing agent calibrated with international standard HAV antibody sample, with the ratified number of 990528, and the sensitivity of 106-127 mIU/ml. Within the proper scope of dilution, make the linear regression with the variables of O.D value and the logarithmic degree of dilution of the standard antibody provided by WHO, to gain the regression formula curve. Based on the degree of dilution of the sample, and the tested O.D. value, which should be brought back into the regressed formula, within the linear range of O.D value of the standard sample, the mIU/ml of the antibody can be calculated out. The anti-HAV gained from this method should be in consistent with that of the Abbott agent.
5.3 HAV IgM antibody test Adopt the ELISA seizing method, with the agent box provided by Tangshan Yi’an Bioengineering Co., Ltd., with the ratified number of 981103.
5.4 HBsAg test Adopt the ELISA method, with the agent box provided by Shanghai Industry Kehua Biological Technology Co., Ltd., with the ratified number of 980605, 980702.
5.5 Abnormality of liver Test ALT test has adopted the Laishi Method, which is normal when it is no more than 40U, produced by Beijing Petrochemical Plant, with the ratified number of 980820.
6 Statistics Analysis Method Make use of the SAS System program to conduct the statistics treatment, to check the positive seroconversion rate of HAV antibody with X2 verification, to express the HAV antibody level with mIU/ml, to compare the values of these two groups with t check.
Results
1. Safety
After the inactivated hepatitis A vaccine is inoculated, the instant side effect hasn’t been found, and the side effects are found after 8-24 hours, and disappeared within 36 hours. The local effects are the rubefaction and swell, and the systematic effects are the slight fever, but not more than 37.5℃ and ALT(See Table 1).
Table 1 Effects of Inactivated Hepatitis A Vaccine Comparison
| Vaccinated dosage (U/dose) |
Primary immunization (first dose) |
| Investigated personnel |
Side effects |
Local effect |
Systematic effect |
| 1000 |
136 |
16 (11.77) |
7 (5.15) |
9 (6.62) |
| 500 |
139 |
17 (12.23) |
8 (5.76) |
9 (6.47) |
|
Booster immunization (second dose) |
| Investigated personnel |
Side effects |
Local effect |
Systematic effect |
|
136 |
1 (0.74) |
0 |
1 (0.74) |
|
137 |
2 (1.40) |
0 |
2 (1.45) |
Note: the data inside the bracket is the effect occurrence rate (%), and the data outside the bracket is the effect personnel.
2. The effects of the HAV antibody in one month after the inactivated hepatitis A vaccine is inoculated
After the inactivated hepatitis A vaccine is inoculated, 32 personnel are selected from each group to test the hepatitis A antibody, within one (1) month after the primary immunization, in the 1000U group and 500U group, the positive seroconversion rate (PSR) of the antibody is 93.8% (30/32) and 90.6% (29/32) respectively, and the GMT is 174 mIU/ml and 146 mIU/ml. According to the statistics, the differences of the PSR [X2 (500U, 1000U) = 0.217, P>0.05] and the GMT [t (500U, 1000U) = 1.799, P>0.05] of these two groups are not significant.
3. The effect of the HAV antibody after the booster immunization of the inactivated hepatitis A vaccine
Since there are 126 persons in 1000U group and 107 persons in 500U group, and in each dosage group, 0.3 month schedule and 0.6 month schedule are set up, there are totally 4 groups. In one (1) month after the booster immunization, the PSR values of the four groups are 100%, whereas the GMT of the 1000U group is higher than that of the 500U group, with the significant difference on statistics. The 95% confidence interval of GMT of each group after the booster immunization is narrow, which shows that the GMT dispersion degree of each group is small(See Table 2).
Table 2. The effects of the antibody in one (1) month after the booster immunization of the inactivated hepatitis A vaccine
| Vaccination schedule |
Dosage
(U/dose) |
Tested personnel |
Positive Seroconversion |
GMT
mIU/ml |
95% Confidence interval |
| Person |
% |
| 0.6 month |
1000 |
71 |
71 |
100 |
7540 |
8355-6349 |
| 500 |
50 |
50 |
100 |
4535 |
5460-3767 |
| 0.3 month |
1000 |
55 |
55 |
100 |
5106 |
6273-4356 |
| 500 |
57 |
57 |
100 |
3269 |
3968-2695 |
t 0.5(1000U, 500U) = 3.874, P<0.001
t 0.5 (1000U, 500U) = 3.094, P<0.01
4. The dynamic trend of the antibody after the inactivated hepatitis A vaccine is inoculated
For the 500U group, after one (1) month the primary immunization is vaccinated, the PSR of the antibody is 90.6%, and the GMT is 146mIU/ml; after 3 months, the PSR is 94.4%, and the GMT is 180mIU/ml; after 6 months, the PSR is 96.9%, and the GMT is 154mIU/ml. In 1, 3 and 6 months after the primary immunization, the PSR and GMT are kept at the similar levels. In one (1) month after the booster immunization, the PSR of the antibody is near to 100%, and the GMT increases obviously, reaching to 4535 mIU/ml.
5. The comparison of the two vaccination schedules of the inactivated hepatitis A vaccine
In one (1) month after the booster immunization of 1000U and 500U groups for 0.3 month and 0.6 month vaccination schedules, the PSRs of antibody are all 100%. But as for the GMT, regardless of the 1000U group or the 500U group, the GMT of the 0.6 month vaccination schedule is higher than that of the 0.3 month vaccination schedule, with the significant statistical difference(See Table 3).
Table 3 The inactivated hepatitis A vaccine comparison at different vaccination schedule
| Vaccinated dosage (U/dose) |
Vaccination schedule |
Tested personnel |
Positive Seroconversion |
GMT
mIU/ml |
| Person |
% |
| 500 |
0.6 month |
50 |
50 |
100 |
4535 |
| 0.3 month |
57 |
57 |
100 |
3269 |
| 1000 |
0.6 month |
71 |
71 |
100 |
7540 |
| 0.3 month |
55 |
55 |
100 |
5108 |
t 1000U(3,.6) = 2.865, P<0.01
t 500U(3, 0.) = 2.374, P<0.05
6. The effects of the IgM antibody after the primary immunization of the inactivated hepatitis A vaccine
In one (1) month after the primary immunization of the inactivated hepatitis A vaccine is inoculated, the HAV IgM antibody is tested, with the PSR of the 1000U group being as 7.94% and the PSR of the 500U group being as 0.93%, which show that the slight quantity of IgM antibody can be generated after the primary immunization, but the immunity is less than the natural infection (See Table 4).
Table 4 The IgM antibody effect after the primary immunization of the inactivated hepatitis A vaccine
|
Vaccinated dosage
(U/dose) |
Tested personnel |
Positive IgM antibody
|
| Person |
% |
| 1000 |
126 |
10 |
7.94 |
| 500 |
107 |
1 |
0.93 |
Discussion
The activated hepatitis A vaccine has been used for 10 years, which proves that some certain level of antibody can be generated [3], effectively preventing the prevalence of the hepatitis A, but some disadvantages still exist [4]. The materials show that [5-7], the inactivated hepatitis A vaccine has good immunogenicity and the effect of preventing the prevalence of the hepatitis A. on the point view of environmental protection, the perspective of the inactivated vaccine is more promising, but it should be proved in the practice. This study initially investigates the safety and the immunogencity of the domestic inactivated hepatitis A vaccine at different dose and different vaccination schedule.
(1) After the inactivated hepatitis A vaccine is applied to Children at 1000U and 500U, the slight side effects have occurred for a period of time, and the ALT is normal, which prove that the domestic inactivated hepatitis A vaccine is safe.
(2) In One (1) month after the primary immunization of the inactivated hepatitis A vaccine, the Positive Seroconversion rate is 93.8% and 90.6% respectively corresponding to the 1000U group and 500U group; the GMT is 174 mIU/ml and 146 mIU/ml respectively, which are much higher than those of preventing from the infection; meanwhile, the comparison of the two groups has no significant statistical difference. In 1 month after the primary immunization of the 500U, the Positive Seroconversion rate is 90.6%, which can prevent from the infection of HAV [6], and the GMT is 146 mIU/ml, being over 7 times of the lower protection value, which indicates that the primary immunization can play the reliable role on protection.
(3) In 1 month after the booster immunization of the domestic inactivated hepatitis A vaccine at 500U (0.6 month), the Positive Seroconversion rate is 100%, the GMT is 4535 mIU/ml, being completely consistent with the vaccination dosage requirement for children.
(4) After the booster immunization at 0.6 month schedule and 0.3 month schedule, regardless of the 1000U group or 500U group, the GMT reaches to the high level, compared these two groups, the GMT of the former is higher than that of the later, with the significant statistical difference, which means the 0.6 month schedule is better than the 0.3 month schedule.
During the experiment, the Smithkine Beecham inactivated hepatitis A vaccine, Havrix (720 EIU), was used to take reference, the impudicity response, and the antibody level are similar or inferior to the domestic inactivated hepatitis A vaccine, but without significant statistical difference. In the comparison with the activated hepatitis A vaccine, the anti-HAV of the inactivated vaccine is better than that of the activated vaccine, and the decreasing of the anti-HAV of the former is slower than that of the latter.
(Thanks to Gao Quanjing, Cui Lianyun, Liu Zhonglin, and Li Haijun for their participation)
References:
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Original: Chinese J of Vaccines and Immunization Feb. 2002,Vol.8 No.1
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