Thermostability, Immunogenicity and Operational Feasibility of Birth-dose Hepatitis B Vaccination in Rural, Ayeyarwady Division, Myanmar

Abstract

A vaccine vial based prospective intervention study was conducted for thermostability of Hepatitis B vaccine at Kyaung-kone township, Ayeyarwady division at grass root level in 2005. During the study period, the ambient room temperature ranged from 23 to 34*C, by using temperature record sheet and study of material as recombinant DNA Hepatitis B vaccine single dose vials in two types of intervention. In stage I, vaccines were transported and stored progressively from the standard 2 to 8*C baseline existing cold chain and maintained without excessive heat exposure. In stage II, vaccines were stored in standard 2 to 8*C at central level, intermediate divisional level and then transported and stored without ice in a vaccine carrier box and maintained without excessive heat exposure. Hepatitis B vaccine is highly heat stable and it can be transported and stored at the home of the midwife at room temperature ranged from 23*C to 34*C with 28*C daily average temperature in vaccine carrier box and maximum length of days to end point for VVM (Vaccine Vial Monitor) of vaccine is nearly 60 days. Therefore Hepatitis B vaccine has operational feasibility thermostability at ambient temperature starting from central and intermediate cold chain level to grass roots level. In conclusion, it is convincing that Hepatitis B vaccine is thermo stable at ambient temperature and it can also be accepted birth dose schedule (within 7 days after birth) at grass roots level.

A two-year (2005-2006) retrospective cohort community based study was conducted for immunogenicity of Hepatitis B vaccine given in under one – children and for detection of the HBV markers HBsAg and HBeAg in mothers between the birth dose and routine schedule immunization in Kyaung-kone township grass root level. Two groups were included, each consisted of 33 infants, given hospital based birth dose schedule (within 7 days after birth) and routine EPI in stage III. Both children were selected based on socio-demographic and socio-economic factors. All studied children were ten months of age and after obtaining the informed consent from their parents, serological Anti HBs was determined by using ELISA, ImmunoComb II Anti HBs to detect the protective antibody level, ≥ to 100 m IU/ml as high seroconversion , 10 to ≤ 100 m lU/ml as good seroconversion and ≤ 10 m lU/ml as poor seroconversion. Not only all the children getting birth dose immunization schedule had good response to Anti HBs seroconversion but also the majority of children with routine immunization schedule had good response. Three children who showed poor seroconversion of Anti HBs, that is Anti HBs less than 10 m lU/ml got routine immunization schedule but their mothers are neither HBsAg nor HBeAg positive in stage IV. Therefore Hepatitis B vaccine is given soon after birth within 7 days gets efficient immunogenicity.

Comment

Myanmar is high prevalence country of Hepatitis B infection. The prevalence of HBs Ag carrier rate of 6.5 % is the second highest among 11 countries in the WHO, South East Asia Region. (1,2). In the high endemic countries the main mode of transmission of Hepatitis B is from mother to child during child birth through infected maternal blood. Without intervention 20 % of neonate will get infection if the mother is HBsAg positive and may be as high as 90 % is she is also positive for HBeAg. The risk of chronic carrier state is also high (80-90%) if the child is infected during the first year of life. For this reason universal administration of Hepatitis B Birth Dose (Hep BD) is one of the key strategy or reducing the prevalence of Hepatitis B infection in highly endemic countries. WHO SEAR had set up a goal to eliminate viral hepatitis as a major public health threat in the Region by the year 2030.(3)

Myanmar NIP had introduced 3 doses of Hepatitis B at 2, 4, 6 months of the age in routine immunization since 2003. HepB BD was also given in public hospitals and most of private hospitals since that time. Pentavalent vaccine that contains Hep B was introduced in 2012 and as there is no supply of monovalent HepB vaccines birth dose was not given as a routine. NiP re-introduced as a routine in public hospitals in December, 2017 (4). The national coverage is still low, 1 % at 2017 and 14 % at 2018. (5). An obstacle in giving Hepatitis B to all newborn is low rate of facility based deliveries in the country, 25 % in 2014 and 37% in 2018. There are difficulties in cold chain logistics and coincidental problems of newborn can be regarded as adverse events following immunization (AEFI) after delivering birth dose to newborn in home deliveries.

Hepatitis B vaccine is effective, inexpensive and safe. It is also relatively heat stable and some countries has practiced out of cold chain use and proved to be effective. (6)

In their first part of the study (Stage I and II) the authors had found that Hep B vaccines stored out of cold chain from intermediate divisional level to grass root level was shown to be thermo-stable for as long as 60 days, by monitoring the Vaccine Vial Monitor (VVM). This suggests the feasibility of out of cold chain use of Hepatitis B vaccine in home deliveries.

In their second part of study, (III and IV) they had measured and compared the sero-conversion rate of children received Hepatitis B vaccine 4 doses (Birth dose, 2, 4, 6 Months) and 3 doses (2, 4, 6months). Out of 66 children in 2 groups only 3 in 3 doses group showed poor sero-conversion (Anti HBs < 10 mIU/L). They found 3 out of 66 children had low sero-conversion rate, but their mothers were negative for both HBsAg and HBeAg.

The findings of this study will provide valuable evidence for NIP in implementing the HepB BD immunization to all newborns. The information will be particularly useful for the rural areas where home deliveries are more frequent. It will also provide evidence to consider out of cold chain use of HepB BD which is one of the obstacles in delivering universal HepB BD in our country.

Prof Saw Win
Editorial Board Member
Member, WHO SEAR ITAG
Vice Chairman, NITAG

Bibliography

1. National Prevalence survey,2015, DMR
2. Country estimates, Country survey 2019, WHO Global and Country Estimates of immunization coverage and chronic HBV infection
3. Regional Action Plan for Viral Hepatitis in South East Asia region WHO 2016-2021.
4. National Immunization Program
5. Ninth Meeting of WHO SEAR ITAG, 2018.
6. WHO Position Paper, Hepatitis B, 2017.

Dr. Khaymar Mya¹, Dr. Khin Pyone Kyi²

1. Ph.D (Public Health) Candidate, University of Medicine (1)
2. Department of Medical Research, Lower Myanmar