[Prospective observation of breakthrough cases and analysis of antibody dynamic changes after two doses of varicella]
1Department of Infectious Diseases, Tianjin Center for Disease Control and Prevention, Tianjin 300011, China.
Insights
Two doses of varicella vaccine significantly reduce breakthrough cases and increase antibody levels in children compared to one dose. However, antibody levels decline over time, suggesting a need for booster shots.
Area of Science:
- Pediatrics
- Immunology
- Vaccinology
Background:
- Varicella (chickenpox) is a common childhood illness.
- Vaccination is effective in preventing varicella, but breakthrough infections can occur.
- The optimal varicella vaccine dosage regimen is crucial for sustained immunity.
Purpose of the Study:
- To compare the breakthrough infection rate and antibody levels in children receiving two doses versus one dose of varicella vaccine.
- To evaluate the long-term immunogenicity of the varicella vaccine in a pediatric population.
Main Methods:
- A prospective observational study involving 1,112 children receiving two doses of varicella vaccine (experimental group) and a control group receiving one dose.
- Three-year follow-up for varicella incidence and serum antibody levels.
- Statistical analysis using chi-squared test, t-test, and variance analysis.
Main Results:
- The cumulative breakthrough rate was significantly lower in the two-dose group (0.54%) compared to the one-dose group (3.96%).
- Geometric Mean Concentration (GMC) of antibodies decreased annually in both groups, but remained higher in the two-dose group.
- The antibody positive rate showed a statistically significant decline over three years in the two-dose group, but remained stable in the one-dose group. The two-dose group consistently had a higher positive rate.
Conclusions:
- Two doses of varicella vaccine provide superior protection against breakthrough infections and higher antibody levels compared to a single dose.
- Despite initial effectiveness, antibody levels and positive rates wane over time, indicating a potential need for booster immunizations.
- Further consideration of strengthening varicella vaccination schedules based on real-world data is warranted.
Abstract:
Objective: To investigate the breakthrough rate and antibody level of children vaccinated two doses varicella vaccine in Tianjin city, and to compare them with those vaccinated one dose. Methods: A total of 1 112 children who were vaccinated two doses varicella vaccine were selected as the experimental group. According to the same street and township, children who had received only one dose within one year of age difference, and whose first injection time was less than one month from the first dose of varicella vaccine in the experimental group were selected as the control group. A three-year prospective observation was conducted on the incidence of varicella in the two groups. 108 pairs of children in the two groups were selected to collect antivaricella serum in the first to third year. The rate of breakthrough cases, antibody level and antibody positive rate were compared by χ2 test, t-test and variance analysis between and within the two groups in three years. Results: The cumulative breakthrough rate of the experimental group was 0.54%(6/1 112), which was lower than that of the control group 3.96% (44/1 112, χ²=29.544, P<0.001). The GMC level of antibody in the experimental group decreased year by year (F=18.291, P<0.001), and the GMC level in the control group also decreased year by year (F=91.383, P<0.001). There was significant difference in GMC level between the two groups (P<0.001). The difference of antibody positive rate in the experimental group was statistically significant in three years (χ²=11.107, P<0.01), there was significant difference in the positive rate between the first year and third year (P<0.01), there was no significant difference in the positive rate of the control group in three years (χ²=3.351, P>0.05). The positive rate of the experimental group was higher than that of the control group (P<0.001). Conclusion: Two doses varicella vaccine can significantly improve the antibody level and positive rate, but it still shows a downward trend with the extension of time. It is necessary to consider strengthening immunization according to the actual situation.
