“My wife and I are both hepatitis B carriers—can we have children?” “I’ve received two doses of the vaccine; can I switch to a different manufacturer’s vaccine for the third dose?” “I got vaccinated against hepatitis B, but tests show no antibodies—could there be something wrong with the vaccine I received?” The “400‑Jin,” who is on the front lines answering hotline inquiries, frequently receives calls like these, all laced with anxiety. To help clear up public confusion, 400‑Jin has compiled a list of ten common questions about hepatitis B, summarizing and thoroughly addressing the most frequent unexpected situations people encounter. Q: After my child received the hepatitis B vaccine, no antibodies were detected. Does this mean she or he lacks immunity to the hepatitis B virus? A: No vaccine can guarantee 100% effectiveness. Due to factors related to the vaccine itself or individual characteristics, some children may fail to develop detectable antibodies after vaccination. This is partly because current methods for detecting hepatitis B surface antibodies have relatively low sensitivity—protective antibodies might already be present in the body but remain undetectable. Additionally, once the hepatitis B vaccine is administered, the immune system develops protection through two pathways: first, humoral immunity produces protective antibodies; second, cellular immunity—via macrophages, K cells, and other immune cells—helps eliminate the hepatitis B virus. In other words, even without antibody production, cellular immunity can still provide protection against the virus. Furthermore, individuals who do not develop antibodies are still protected by “herd immunity”: when nearly everyone around them is vaccinated and thus resistant to the virus, an immune barrier forms, naturally shielding those within it. Q: How effective is the hepatitis B vaccine? A: The hepatitis B vaccine is an effective, economical, and safe measure for preventing hepatitis B. Since 1982, widespread vaccination has reduced the global prevalence of chronic hepatitis B infection among children under five years old to an estimated 1.3% by 2015.[1] In May 2012, China achieved the World Health Organization’s target of keeping the hepatitis B surface antigen carriage rate among children under five below 2%, and later, in 2017, surpassed this goal by reducing it further to below 1%. It is estimated that since 1992, at least 80 million people nationwide have been spared hepatitis B infection, and at least 19 million have been prevented from becoming chronic carriers of the hepatitis B surface antigen.[2] Q: Why do I still test negative for antibodies after receiving the hepatitis B vaccine? A: We refer to the phenomenon of failing to detect surface antibodies after vaccination as “non-response.” Why does non-response occur? While the exact mechanisms are not yet fully understood, several key factors have been identified: (1) Genetic studies suggest that antibody production following hepatitis B vaccination is linked to human leukocyte antigens (HLA). HLA‑DR7, HLA‑DR3, and defects in T lymphocytes may contribute to non-response or low response. (2) Some immunological research indicates that reductions in the number or function of certain immune cells can also impair antibody production, leading to non-response. (3) Hepatitis B virus mutations: The virus readily mutates, altering its biological characteristics. If the vaccine cannot effectively recognize these variants, it will lose its efficacy. (4) Prior infection: If a person has already been exposed to a small amount of the hepatitis B virus before vaccination, existing testing methods may fail to detect surface antibodies. In such cases, the body enters a state of immune tolerance, unable to mount a normal immune response to the vaccine. (5) Insensitive testing methods: Current “hepatitis B two‑plus‑two” assays have relatively low sensitivity, meaning protective antibodies might already exist in the body but go undetected, falsely suggesting no immunity. (6) Other factors: Age, gender, body weight, smoking, alcohol consumption, vaccine type, injection site, dosage, intervals between doses, maternal serum viral load, and more can all influence non-response. Moreover, conditions such as malnutrition, HIV/AIDS, organ transplantation, or dialysis—which compromise immune function—can also lead to non-response. Q: I’m seven months pregnant, and both my husband and I are hepatitis B carriers. What precautions should we take after the baby is born to prevent hepatitis B transmission? A: To maximize newborn protection, the infant should receive the hepatitis B vaccine and 100 IU of hepatitis B immune globulin as soon as possible—ideally within 24 hours of birth—and complete the full course of hepatitis B vaccinations at one month and six months of age. Q: During routine hepatitis B vaccination, what issues might arise if the three consecutive doses come from different manufacturers or use different vaccine types? Is it still effective? A: Using vaccines from different companies or different types, or alternating between doses, generally does not affect overall efficacy. However, it is preferable to stick to the same brand and formulation throughout the series. Q: After a newborn completes the full three‑dose hepatitis B vaccination schedule, when can antibody testing be performed? A: For most infants, antibody testing (anti‑HBs) is not required after completing the full course. However, if the mother is HBsAg‑positive, the newborn should undergo antibody testing. Blood can be drawn one month after finishing the full vaccination series; if anti‑HBs levels are below 10 mIU/mL, a booster dose may be recommended. Q: Can the hepatitis B vaccine be administered simultaneously with other vaccines? A: According to the “National Immunization Program: Childhood Immunization Schedule and Instructions (2016 Edition),” all vaccines included in the national immunization program—including the hepatitis B vaccine—may be given concurrently. When administering the hepatitis B vaccine alongside other vaccines, injections should be spaced apart at different sites. Q: How long does the protection provided by the hepatitis B vaccine last? A: Antibody levels generated after vaccination gradually decline over time. Higher initial antibody titers tend to persist longer. Typically, after receiving three doses, about 97% of individuals can detect hepatitis B surface antibodies (anti‑HBs) within one to three months; the level remains stable for about a year, after which the seroconversion rate slowly decreases, falling to roughly 74% by the third year post‑vaccination, accompanied by a gradual decline in antibody titers. Extensive data indicate that for those who respond to the vaccine, protective effects generally last at least 20 years.[3] Q: After contracting the hepatitis B virus, what are the chances of progressing to chronic hepatitis, cirrhosis, or liver cancer? A: ★Infants under one year old: Approximately 90% may develop chronic infection. ★Children aged one to four: 20%–50% may progress to chronic infection. ★Adults: Less than 10% develop chronic infection. ★Among chronic HBV carriers, 15%–25% may die prematurely from cirrhosis or liver cancer. ★Globally, about 80% of hepatocellular carcinoma cases are attributable to HBV infection.[2] Q: Who is most susceptible to hepatitis B infection? A: Humans are the only natural host for the hepatitis B virus, making the population broadly vulnerable. High‑risk groups can be divided into two categories: ★Newborns and young children lacking immunity, especially those whose mothers are HBsAg‑positive. ★Other priority groups: Healthcare workers, individuals frequently exposed to blood or bodily fluids, childcare facility staff, spouses, family members, or close contacts of hepatitis B patients or carriers, organ transplant recipients, regular blood transfusion or blood product users, people with compromised immune systems, those prone to injury, individuals engaging in promiscuous sexual activity or multiple partners, and intravenous drug users. References: [1] https://www.who.int/zh/news-room/fact-sheets/detail/hepatitis-b [2] http://www.chinacdc.cn/zxdt/201312/t20131230_92034.htm [3] http://www.nhc.gov.cn/jkj/s3582/201307/618a3ef7e2eb49a59cdbbfa738208cfb.shtml

In China, during the 1960s and 1970s, the annual incidence of pertussis ranged from 100 to 200 cases per 100,000. Beginning in the 1960s, vaccination with the DPT vaccine was introduced, and by 1978, it had been incorporated into the national immunization program. Following the widespread use of the DPT vaccine, the incidence declined markedly. Since 2008, the reported national incidence of pertussis has remained below 0.5 per 100,000. With the exception of neonatal tetanus, tetanus in other population groups is not classified as a legally notifiable infectious disease in China. From 2007 to the present, no cases of diphtheria have been reported nationwide.

Vaccination is the most cost-effective and efficient measure for preventing and controlling infectious diseases. Before vaccines were developed, epidemics such as plague and smallpox ravaged humanity, and even influenza claimed the lives of tens of millions. We must not let a few vaccine-related incidents make us forget the fear that has long been imposed by infectious diseases.

Before vaccines were developed, infectious diseases such as diphtheria, tetanus, and meningitis were leading causes of death and illness worldwide. The development of vaccines stands as one of the greatest public health achievements in human history, significantly reducing mortality from infectious diseases. Currently, there is a substantial disparity in vaccination coverage between Australian adults and infants: over 93% of infants are vaccinated, whereas adult vaccination rates range from 53% to 75%. Adults still require many vaccinations to mitigate their risk of disease, particularly for certain high‑risk conditions.