Effectiveness of single-dose administration of inactivated hepatitis A virus vaccination in the Republic of Korea armed forces, 2013-2016

Gender differences in hepatitis A seropositivity rates according to the Republic of Korea's vaccination policy

BACKGROUND

This study aimed to investigate differences in the anti-hepatitis A virus (HAV) antibody seropositivity rate by age and gender.

METHODS

We collected information on anti-HAV immunoglobulin G and immunoglobulin M status from samples submitted for HAV antibody testing in 2012-2022. A total of 1,333,615 cases were included in the analysis.

RESULTS

By age, the seropositivity rate was represented by a U-shaped curve, such that the rate was low for the group aged 20 to 39 years and higher in those who were younger or older. Over time, the curve shifted rightward, and the seropositivity rate declined gradually in the group aged 35 to 39 years and older. A gender-based difference in antibody seropositivity rate was especially noticeable in the group aged 20 to 29 years. This difference between genders widened in the participants' early 20s-when men in the Republic of Korea enlist in the military-and the divergence continued subsequently for older individuals.

CONCLUSION

These results indicate a higher risk of severe infection among older individuals and a gender-based difference in seroprevalence. Therefore, it is necessary to implement policies to promote vaccination in adults.

Analysis of the Number and Type of Vaccinations Performed among Polish Soldiers in 2018-2021

Vaccination is a very common topic, but it is rarely raised or discussed with respect to military members. Soldiers are one of the main professional groups to be immunized on a regular basis. The military actively participates in research on new vaccine preparations. This paper presents data from 2018-2021 on vaccination among Polish soldiers. The material obtained from the Central Register of Vaccination for Professional Soldiers was analyzed using descriptive statistical methods. The number of injections performed in a given period depends on the location of the ongoing missions and the vaccination schedule specific to a given Polish Military Contingent. In Poland, soldiers undergo preventive vaccinations in accordance with the scheme developed by the Armed Forces Operational Command, taking into account the specific nature of the service, epidemiological risks and the calendar of current preventive vaccinations. Soldiers serving abroad are immunized against typhoid, hepatitis A, hepatitis B, rabies, measles, tick-borne encephalitis, Japanese encephalitis, polio, diphtheria, meningococcal disease, chickenpox, cholera and yellow fever. Regular vaccinations for soldiers are necessary to minimize the spread of infectious diseases, and they have a beneficial effect upon the effectiveness of military operations.

One or two doses of hepatitis A vaccine in universal vaccination programs in children in 2020: A systematic review

BACKGROUND

Hepatitis A virus (HAV) is a global health concern as outbreaks continue to occur. Since 1999, several countries have introduced universal vaccination (UV) of children against HAV according to approved two-dose schedules. Other countries have implemented one-dose UV programs since 2005; the long-term impact of this schedule is not yet known.

METHODS

We conducted a systematic literature search in four electronic databases for data published between January 2000 and July 2019 to assess evidence for one-dose and two-dose UV of children with non-live HAV vaccines and describe their global impact on incidence, mortality, and severity of hepatitis A, vaccine effectiveness, vaccine efficacy, and antibody persistence.

RESULTS

Of 3739 records screened, 33 peer-reviewed articles and one conference abstract were included. Rapid declines in incidence of hepatitis A and related outcomes were observed in all age groups post-introduction of UV programs, which persisted for at least 14 years for two-dose and six years for one-dose programs according to respective study durations. Vaccine effectiveness was ≥95% over 3-5 years for two-dose programs. Vaccine efficacy was >98% over 0.1-7.5 years for one-dose vaccination. Antibody persistence in vaccinated individuals was documented for up to 15 years (≥90%) and ten years (≥74%) for two-dose and one-dose schedules, respectively.

CONCLUSION

Experience with two-dose UV of children against HAV is extensive, demonstrating an impact on the incidence of hepatitis A and antibody persistence for at least 15 years in many countries globally. Because evidence is more limited for one-dose UV, we were unable to draw conclusions on immune response persistence beyond ten years or the need for booster doses later in life. Ongoing epidemiological monitoring is essential in countries implementing one-dose UV against HAV. Based on current evidence, two doses of non-live HAV vaccines are needed to ensure long-term protection.

Universal Single-Dose Vaccination against Hepatitis A in Children in a Region of High Endemicity

Since August 2012, universal single-dose vaccination in children aged at least three years has been implemented in the Republic of Tuva, which was previously the region most affected by hepatitis A in Russia. The objective of this cross-sectional study was the assessment of the immunological and epidemiological effectiveness of vaccination program five years following its implementation. In the pre-vaccination period, anti-HAV antibody detection rates in Tuva was 66.0% [95% CI: 56.3-74.6%] in children aged 10-14 years and reached a plateau (>95%) by age 20-29 years. Annual incidence rates in children under 18 years of age peaked at 450-860 per 100,000 in pre-vaccination years but dropped to 7.5 per 100,000 in this age group and to 3.2 per 100,000 in the total population one year after the start of vaccination. Since 2016, no cases of hepatitis A has been reported in Tuva. Serum anti-HAV antibodies were quantified in samples from healthy children following single-dose vaccination. Protective anti-HAV antibody concentrations (≥10 mIU/mL) were detected in 98.0% (95% CI: 96.2-99.0% (442/451)) of children tested one month after single-dose immunization, in 93.5% (95% CI: 91.0-95.4% (477/510)) and in 91.1% (95% CI: 88.2-93.4% (422/463)) of children one year and five years after single-dose immunization, respectively. Anti-HAV antibody geometric mean concentrations were similar in sera collected one month, one year, and five years following single-dose vaccination: 40.24 mIU/mL, 44.96 mIU/mL, and 57.73 mIU/mL, respectively (p > 0.05). These data confirm that single-dose vaccination is an effective method of bringing hepatitis A under control in a short period of time in a highly endemic region.