1.Why is it necessary to test the hepatitis B two-and-a-half pairs before hepatitis B vaccination? Hepatitis B two-and-a-half is the abbreviation for a group of commonly used indicators for detecting hepatitis B infection status and immune status, including hepatitis B surface antigen, surface antibody, e antigen, e antibody and core antibody. A positive hepatitis B surface antigen means that you are infected with the hepatitis B virus, and a positive e antigen and core antibody means that you have a “major triplet”, and a positive e antibody and core antibody means that you have a “minor triplet”, which means that the hepatitis B vaccine is not effective. Positive surface antibodies represent immunity, which can be generated after hepatitis B vaccination, when other indicators are negative, or it can be a sign of recovery from natural infection, when accompanied by positive core antibodies. In both cases, hepatitis B vaccination is not required. Therefore, the hepatitis B vaccination is usually preceded by a hepatitis B half test, which will determine whether vaccination is necessary. Since the safety of hepatitis B vaccine is very good, according to the different carrying rates in different places, it is also recommended to vaccinate hepatitis B vaccine directly without testing. 2.Is the hepatitis B half test qualitative or quantitative? Quantitative test is better than qualitative test because quantitative test can help to determine the titer of hepatitis B surface antibody in addition to negative or positive test. It is generally accepted that a healthy person with 10 units/liter of hepatitis B surface antibody indicates immunity; hepatitis B surface antibody >100 units/liter indicates good immunity, which lasts for a longer period of time (except for children whose parents are chronic hepatitis B or hepatitis B virus carriers, who become high-risk children). The disadvantage of quantitative tests is that they are expensive and are not carried out in many primary hospitals. At this time, qualitative tests can also be used as a rough judgment. 3.Can pregnant women get the hepatitis B vaccine? Yes. Pregnant and lactating women are not contraindicated for the hepatitis B vaccine. In fact, since hepatitis B virus can be transmitted in families and mother-to-child transmission is the main factor of hepatitis B vaccine immunization failure, hepatitis B vaccination should be recommended for pregnant women and lactating mothers who are at high risk of hepatitis B virus infection in their families. Hepatitis B indicators can be tested before vaccination, and pregnant women who are not infected with hepatitis B virus should be vaccinated with hepatitis B vaccine as soon as possible. Pregnant women who are already infected with hepatitis B virus (surface antigen positive) do not need hepatitis B vaccination. 4.Can people with chronic diseases get hepatitis B vaccine? Since people with chronic diseases are often susceptible to hepatitis B virus infection and hepatitis B infection often causes more serious consequences, in general, if a chronic patient’s condition is stable, he/she should be vaccinated against hepatitis B in a timely manner. Since some chronic diseases also affect immune function and thus the durability of the vaccine effect, hepatitis B surface antibody titers should also be monitored regularly for timely booster vaccination. Individual experts have suggested that it is better not to vaccinate patients with autoimmune diseases, but this is mostly based on theoretical speculation and has no solid basis. However, it should be noted that the vaccine instructions state that patients with chronic and serious diseases (such as heart and kidney diseases), severe organ malformations, and severe skin eczema cannot receive hepatitis B vaccine. 5.How long can I be protected after receiving hepatitis B vaccine? The current recommended immunization schedule is 0,1,6 months, which means that three doses are given within six months, counting from the day of the first dose, the second dose at full term, and the third dose at full term. The dose for children and adolescents is 5 micrograms (ug) per dose. Foreign studies have shown that the use of 2.5 ug or 10 ug of yeast hepatitis B vaccine induces antibody production in normal children, but the 10 ug dose induces higher levels of hepatitis B surface antibodies. Hepatitis B surface antibody titers are highest from 1 to 6 months after completion of full immunization and tend to decrease thereafter. About half of the infants who received yeast hepatitis B vaccine had serum antibody titers below 10 units/liter by the age of 10 years, but children with reduced or negative antibody titers could rapidly develop high titers of antibodies after a booster dose, so the protective effect of recombinant hepatitis B vaccine for normal children is generally considered to last at least 10 years. 6.What about babies born to mothers with hepatitis B virus? Mother-to-child transmission is the most important cause of chronic hepatitis B virus infection in China. The yeast hepatitis B vaccine, 5 micrograms, has a protective effect of 60%-80% in the 0, 1 and 6 month programs, and its first immunization should be given as early as possible, and no later than 24 hours after birth. Experts at home and abroad mostly require the use of active-passive combined immunization for infants of hepatitis B virus-carrying mothers, i.e. at least 100 units (IU) of hepatitis B immunoglobulin should be injected within 12 hours of birth, and hepatitis B vaccine should be injected at different sites at the same time. 7.How long after the full course of hepatitis B vaccination can blood be drawn for antibody testing? Normal newborns of hepatitis B surface antigen-negative mothers and children and adults with normal immune function respond well to hepatitis B vaccine, so routine monitoring of hepatitis B surface antibody is not required after vaccination. Infants of hepatitis B surface antigen-positive mothers and other people with potential risk factors (such as hepatitis B patients in the family) should be tested for hepatitis B surface antibodies 1-6 months after completing the three-dose vaccination program. Those with negative hepatitis B surface antibodies or antibody titers below 10 units/liter should receive a booster injection in a timely manner to keep their hepatitis B surface antibodies above the protective level and minimize the occurrence of hepatitis B virus infection. Those who are negative for hepatitis B surface antibody and hepatitis B surface antigen should receive a booster vaccination in order to generate immunity. 8.What should I do if I have no antibodies after receiving hepatitis B vaccination? In medical science, it is called no response to hepatitis B vaccine when the hepatitis B surface antibody is still negative after the whole vaccination. Most of them are not “true” non-responders, and most of them can still produce protective level of hepatitis B surface antibodies after booster vaccination. If antibodies are still not produced, regular follow-up is recommended to prevent infection with hepatitis B virus. 9.How often do I need to be re-vaccinated with hepatitis B vaccine? Although a significant proportion of people with normal immune function disappear or fall below the protective titer of hepatitis B surface antibodies 5-10 years after vaccination, the occurrence of hepatitis B virus infection is rare, so it is not considered necessary to replant. As for infants of hepatitis B surface antigen-positive mothers, people with suppressed or impaired immune function, and people who have received a large amount of blood because of the increased chance of infection with hepatitis B virus and the tendency to become chronic after infection, many scholars believe that these high-risk groups should be monitored for antibody titers in areas where conditions exist and replanted if necessary to keep the hepatitis B surface antibody above 10 units per liter. 10. Is it easier to produce antibodies with higher doses of hepatitis B vaccine? At present, the specifications of hepatitis B vaccine used in China mainly include yeast recombinant hepatitis B vaccine 5mg and 10mg, and Chinese hamster kidney hepatitis B vaccine 20mg. Early studies found that different doses of hepatitis B vaccine are equally effective in preventing hepatitis B virus, but the titers of hepatitis B surface antibodies produced may be different. Foreign studies have compared yeast recombinant hepatitis B vaccine 5 mg and 10 mg for blocking mother-to-child transmission of hepatitis B. Antibody titers were significantly higher with each 10 mg dose than with each 5 mg dose, but no large-scale authoritative research study has yet demonstrated that the amount of hepatitis B vaccine administered per dose is proportional to the immunoprotective effect. For the method of increasing the dose of injection, there is no test to prove that it is harmful to human. 11.Is the dose of hepatitis B vaccine for children the same as that for adults? The dose of vaccine varies depending on the type of vaccine and the population used. For the initial blood-borne hepatitis B vaccine, children are generally given 10µg/dose per injection at 0, 1, and 6 months; adults can be vaccinated at 20µg/dose per injection at 0, 1, and 6 months. The general dose of genetic recombinant vaccine is 5-10µg/session. For infants born to HBsAg positive mothers and adults over 18 years old, the vaccine dose should be larger and can be given at 10µg-20µg as appropriate depending on the target. The dose for adults is usually 20µg per dose in China, and the recommended dose in the United States is 20µg per dose. 12.How long does it take to repeat the hepatitis B vaccine from the beginning if I miss it? The basic immunization of hepatitis B vaccine is divided into 3 times, in 0, 1 and 6 months, and it is generally believed that each delay of 1-2 months will not have any effect on the immunization effect. Some scholars in the United States have studied the interval of one year between each of the three doses of hepatitis B vaccine and found that there was no significant effect on antibody production. In fact, the 0, 1, 6 schedule was based on the response of the majority of vaccinees and a cost-benefit analysis at the time. The response to hepatitis B vaccine is not quite the same for each individual. A small number of children develop antibodies with a single injection, and some children do not develop antibodies with multiple injections. Therefore, there is no such thing as how long after a missed vaccination it is necessary to repeat the vaccination from the beginning. If the antibody is positive and the titer is high, you can stop vaccinating, if the antibody titer is not high, you can vaccinate once, and if the antibody continues to be negative, you can revaccinate 2-3 times. 13.How long does it take to get a booster shot after having antibodies? There is no fixed schedule for how long it takes to get a booster shot after the hepatitis B vaccination has produced antibodies, and it should be considered on an individual basis. Epidemiologists have found that 10 years after hepatitis B vaccination, antibodies can still be detected in the blood of a significant number of people, and most antibody-negative people can quickly produce antibodies with a booster dose, indicating the existence of immune memory, so their view is that a booster is not needed within 10 years after vaccination. However, there are many clinical experts who believe that since China is a highly endemic area for hepatitis B, with high chances of exposure and infection in daily life, it is best to keep hepatitis B surface antibodies above the protective level, so individual risk factors should be fully considered and blood titers of hepatitis B surface antibodies should be monitored regularly to determine how often booster shots are needed.