Cross-neutralization of antibodies induced by inactivated SARS-CoV-2 vaccine against Beta and Delta variants / 中华微生物学和免疫学杂志

Objective:To evaluate the in vitro cross-neutralization of serum antibodies in human and mice immunized with inactivated SARS-CoV-2 vaccine against Delta and Beta variants. Methods:Human serum samples after a second and a third dose of inactivated SARS-CoV-2 vaccine and mouse serum samples after a two-dose vaccination were collected. The neutralizing antibodies in the samples against SARS-CoV-2 strains of prototype, Delta and Beta variants were detected using micro-neutralization assay in biosafety level Ⅲ laboratory. The seroconversion rates and geometric mean titers (GMTs) of antibodies were calculated.Results:The seroconversion rates of antibodies in human serum samples against different SARS-CoV-2 strains were all above 95%. After two-dose vaccination, the GMTs of neutralizing antibodies against the prototype, Delta and Beta strains were 109, 41 and 15, respectively. The GMTs decreased by 2.7 folds and 7.3 folds for the Delta and Beta variants as compared with the prototype strain. After the booster vaccination, the GMTs of neutralizing antibodies against the prototype, Delta and Beta strains were 446, 190 and 86, respectively. The GMTs of neutralizing antibodies against Delta and Beta variants decreased by 2.3 folds and 5.2 folds as compared with that against the prototype strain. The seroconversion rates of antibodies against different SARS-CoV-2 strains in mouse serum samples were all 100%. The GMTs of neutralizing antibodies against the prototype, Delta and Beta strains were 2 037, 862 and 408, respectively. The GMTs decreased by 2.4 folds and 5.0 folds for the Delta and Beta variants.Conclusions:Inactivated SARS-CoV-2 vaccine could induce a certain level of neutralizing antibodies against Delta and Beta variants in both human and mouse models. Moreover, a third dose of vaccine induced higher levels of neutralizing antibodies against Delta and Beta variants in human. This study provided valuable data for the clinical application and protective evaluation of the inactivated SARS-CoV-2 vaccine.

Long-term Protection Against the Hepatitis B Virus Detected Through an Early Response to a Booster Dose Injection

To determine the duration of protection conferred by the hepatitis B (HB)vaccination and the necessity of a booster dose. Methods: Immediately after the initial bloodsampling, 252 youths (aged 18.8-20.5 years, 52% females) with a history of neonatal HBvaccination with one dose of the HB vaccine received a booster. Serum concentrations ofantibodies against the HB surface antigen were assessed in samples collected before and10-14 days after the booster. Seroconversion from concentrations <10 to ?10 IU/L weredefined as a positive immune response. Results: Of the 252 participants, 131 were sero-susceptible and 114 responded. Conclusions: Nearly 90% of young people preserved theirlong-term protection; the results of this study do not support the use of an HB boostervaccination

Immunogenicity and Safety of a DTaP-IPV//PRP~T Vaccine (Pentaxim) Booster Dose During the Second Year of Life in Indian Children Primed with the Same Vaccine.

Objective: To evaluate the immunogenicity and safety of a pentavalent (diphtheria, tetanus, acellular pertussis, inactivated poliovirus, Hib polysaccharide-conjugate) combination vaccine booster dose. Design: Multicenter, open, Phase III clinical study. Setting: Two tertiary-care hospitals in Delhi and Vellore, India. Participants/patients: 207 healthy Indian children. Intervention: The DTaP-IPV//PR~NT vaccine (Pentaxim) was given at 18-19 months of age to children who had been primed with the same vaccine at 6,10,14 weeks of age. Main outcome measures: Immunogenicity was assessed before and 1 month after the booster. Safety was evaluated from parental reports, and investigator assessments. Results: At 18-19 months of age, before boosting, the SP rates against diphtheria, tetanus, poliovirus and PRP were 82.3-100%; 90.0% of participants had anti-PRP ≥0.15 μg/mL. Anti-poliovirus titers were ≥1:8 dilution in 97.9-98.4% of participants. Anti-PT and FHA titers (≥5 EU/mL) were detectable in 82.5% and 90.8% of participants, respectively. One month after the booster dose, SP rates were 99.5% for PRP (≥1.0 μg/mL), 100% for diphtheria, tetanus (≥0.1 IU/mL) and polioviruses (≥8:1/dilution). Seroconversion (4 fold post-booster increase in anti-PT and -FHA concentration) occurred in 96.8% and 91.7%, respectively. Geometric mean concentrations (GMC) increased from 11.7 to 353.1 EU/mL and from 18.2 to 363.4 EU/mL for anti-PT and anti- FHA, respectively. Anti-PRP GMC increased from 1.75 to 70.5 μg/ mL. Vaccine reactogenicity was low; severe solicited reactions were reported by <1.4% of participants. Conclusion: The DTaP-IPV//PRP-T vaccine booster at 18-19 months of age was well tolerated and induced strong antibody responses.

Time interval for booster vaccination following reexposure to rabies in previously vaccinated subjects.

Background: In rabies endemic areas, re-exposures to rabies are quite common and the incidence could be up to 15%. The recent guidelines of World Health Organization do not specify the duration of protection provided by previous pre- or post exposure prophylaxis. This often puts the treating physician in a dilemma in such cases of re-exposure. Objective: Study the time interval between primary and booster vaccination in individuals who have taken previously a full course of either pre- or post exposure prophylaxis and are now re-exposed to rabies. Methods: The data obtained through a literature search using Pubmed and advanced Google search along with data from in house clinical trials were used for analysis. Sixty-six vaccine cohorts spanning more than 27 years from 1983 to 2010 from six countries were studied. The duration of protection offered by previous vaccination was assessed by using a surrogate marker of adequate (> 0.5 IU per mL) rabies virus neutralizing antibody levels in the individuals vaccinated either by pre-exposure or post exposure regimens received by intramuscular or intradermal routes. Results: The proportions of 2,795 subjects who had received prior post-exposure immunization and produced rabies virus neutralizing antibody levels of less than 0.5 IU per mL were 0.07% and 0.14% at the end of the first and third month post primary vaccination. All 577 subjects with previous pre-exposure vaccination had antibody responses above 0.5 IU per mL at the end of the first and third month post primary vaccination. Conclusion: We concluded that it may be safe for up to three months after previous pre- or post exposure vaccination to not administer boosters to healthy subjects who have been re-exposed to rabies.

A study of the current(2003-2005) prevalence of anti-HBs and immunologic memory of hepatitis B vaccine in children from the central area of Korea / 소아과

PURPOSE: This study was conducted to assess the current(2003-2005) prevalence of anti-HBs and immunologic memory for Hepatitis B vaccine in children from the central area of Korea. METHODS: Subjects were chosen from children and adolescents who received tests for hepatitis B surface antigen(HBsAg) and anti-HBs at Dankook University Hospital from March 2003 to May 2005. Among these, antibodies to hepatitis B core antigen(IgG anti-HBc) were checked. A single booster vaccination was performed on children whose anti-HBs titers were under 10 mIU/mL. One month after booster vaccination we rechecked the anti-HBs titer. RESULTS: A total of 3,277 subjects were tested for HBsAg/anti-HBs, and 1,913(58.4 percent) of them were positive for anti-HBs. Of these, 29 subjects(0.9 percent) were positive for HBsAg. Positive results for anti-HBs by age were 78.6 percent for 6-12 months of age, 62.7 percent for 1-3 years of age, 51.9 percent for 4-6 years of age, 49.5 percent for 7-12 years of age, 63.4 percent for 13-15 years of age and 72.2 percent for 16-18 years of age. The 80 subjects who were tested negative for HBsAg/anti-HBs received a single booster vaccine, 71 subjects were tested positive for antibodies. IgG anti-HBc titer was checked for 169 of the subjects, 5 subjects were positive. CONCLUSION: In our study, a significant anamnestic response was observed in 88.8 percent of children. This is believed to be a result of the relatively long immunologic memory effect of the hepatitis B vaccination in children from the central area of Korea.

Studies of the Change of Antibody Titers after Vaccination of Haemophilus Influenzae PRP-T Conjugate Vaccine

PURPOSE: This study was carried out to survey the serum anti-PRP titers after the completion of a primary series with 3 doses of the PRP-T conjugate vaccine(ACT-HIBTM), to evaluate the necessity of booster vaccination. METHODS: One hundred twenty healthy infants who went for consultations at Moon Hwa hospital between December 1999 to May 2001 were vaccinated at two, four and six months after birth. The serum antibody levels were measured at 7-8 months and 19-20 months of age by the "Farr" type of radioimmunological method at Aventis Pasteur International in France. RESULTS: The geometric mean of Anti-PRP titers were 24.6 microgram/mL at 7-8 months and then fell to 2.10 microgram/mL at 19-20 months. Minimum Anti-PRP titer was 0.75 microgram/mL at 7-8 months, and 0.1 microgram/mL at 19-20 months. Maximum Anti- PRP titer was 99.2 microgram/mL at 7-8 months, and 9.1 microgram/mL at 19-20 months. Subjects of Anti-PRP titers more than 0.15 microgram/mL were 100% at 7-8 months, and 97.0% at 19-20 months, and subjects of Anti-PRP titers more than 1.0 microgram/mL were 98.3% at 7-8 months, and 61.6% at 19-20 months. CONCLUSION: The Anti-PRP titers at 7-8 months were very high but rapidly decreased at 19-20 months of age, so the necessity of booster vaccination could be considered in Korean children.

Epidemiological Study of Rubella Outbreak in Chungchungnam-Do in Middle and High School Students in a Local Small Town

BACKGROUND: Rubella is a viral infection of childhood. Its clinical manifestations are not serious, but rubella infection in early pregnancy can result. in congenital rubella syndrome. In Korea, there have been several rubella outbreaks in 1996. We performed an epidemiological study about a rubella outbreak in middle and high school students in an isolated small town. METHODS: This study was carried out from March 22, 1996 to April 29, 1996. The target populations were middle and high school students(middle school-1,369, high school-966 students) in Namseonri. They were given a questionnaire containing sociodemographic characteristics, past vaccination history and rubella-like symptoms. We selected 70 clinically diagnosed patients and 233 students with rubella-like symptoms from the questionnaires. Through IgM and IgG ELISA we analyzed the serum of selected students. All of the middle and high school students except those with clinical rubella were vaccinated on March 27. RESULTS: 1) The number of IgM positive students was 65 among 303 selected students. 58 students among the IgM positive group were diagnosed clinically, and 7 patients and subclincal infection. 2) Male patients were more predominant than female, especially in high school(M : F, 2 : 1 in middle school, 7 : 1 in high school). 3) Positive rates of IgG gradually increased by grade from 58.3% to 92.9% (1st grade of middle school to 3rd grade of high school). 4) IgG titer of the booster vaccinees(2nd and 3rd tirade female, high school) was significantly higher than younger female students(p<.05). 5) After mass vaccination, 3 more patients caught rubella in high school during 1 month follow-up. CONCLUSIONS: Among 2335 students, IgM positive patients were 65 with incidence rate of 2.8%. Mass vaccination of the studentg an effective preventive method in a rubella outbreak.