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BackgroundBBIBP-CorV vaccine with two doses and an interval of 3-4 weeks had been proved to have good immunogenicity and efficacy as well as an acceptable safety profile according to our initial research and other similar studies. Maintaining adequate neutralizing antibody levels is also necessary for long-term protection, especially in the midst of the COVID-19 pandemic. Our aim was to evaluate the immune persistence of neutralizing antibody elicited by BBIBP-CorV vaccines with day 0-14, 0-21 and 0-28 schedule, and assess the immunogenicity and safety of a homologous booster dose in the high-risk occupational population aged 18-59 years. MethodsA total of 809 eligible participants, aged 18-59 years, were recruited and randomly allocated to receive BBIBP-CorV vaccine with day 0-14, 0-21 or 0-28 schedule respectively between January and May 2021 in Taiyuan City, Shanxi Province, China among the public security officers and the airport ground staff in initial study. In this secondary study, the responders (GMT [≥] 16) at day 28 after priming two-dose vaccine were followed up at months 3, 6 and 10 to evaluate the immune persistence of three two-dose schedules. At month 10, eligible participants of three two-dose schedules were received a homologous booster dose respectively (hereafter abbreviated as 0-14d-10m group, 0-21d-10m group and 0-28d-10m group), and followed up at day 28 post-booster to assess the safety and immunogenicity of the booster dose. The contents of follow-up included the blood samples, oropharyngeal/nasal swabs, and adverse reactions collection. The main outcomes of the study included geometric mean titers (GMT) of neutralizing antibody to live SARS-CoV-2, the positive rates of different criteria and the constituent ratio of GMT of neutralizing antibodies at different follow-up point. Meanwhile, we explored the kinetics of antibody levels of different vaccination regimens by generalized estimating equations (GEE) and used exponent curve model to predict the duration of maintaining protected antibody after the booster dose. We also determined predictors of maintaining protected antibody level within 10 months after the second dose by Cox proportional hazards regression model and nomogram. The trial was registered with ChiCTR.org.cn (ChiCTR2100041705, ChiCTR2100041706). ResultsThe number of 241, 247 and 256 responders (GMT [≥] 16) at day 28 after two-dose BBIBP-CorV vaccine in 0-14d, 0-21d and 0-28d schedule were followed-up at months 3, 6, and 10 for immune persistence evaluation. At month 10, a total of 390 participants were eligible and received a booster dose with 130 participants in the 0-14d-10m, 0-21d-10m and 0-28d-10m group respectively, of whom 74.1% (289/390) were male, with a mean age of 37.1{+/-}10.3 years. The GMT of neutralizing antibody in 0-28d-10m and 0-21d-10m group were significantly higher than 0-14d-10m group at month 3 (GMT: 71.6 & 64.2 vs 46.4, P<0.0001), month 6 (GMT: 47.1 & 42.8 vs 30.5, P < 0.0001) and month 10 (GMT: 32.4 vs 20.3, P < 0.0001; 28.8 vs 20.3, P=0.0004) after the second dose. A sharply decrease by 4.85-fold (GMT: 94.4-20.3), 4.67-fold (GMT: 134.4-28.8) and 4.49-fold (GMT: 145.5-32.4) was observed from day 28 to month 10 after the second dose in 0-14d-10m, 0-21d-10m and 0-28d-10m group, respectively, and they had similar decline kinetics (P=0.67). At 28 days after booster dose, a remarkable rebound in neutralizing antibody (GMT: 246.2, 277.5 and 288.6) were observed in three groups, respectively. Notably, the GMT after booster dose was not affected by priming two-dose schedule. The predictive duration of neutralizing antibody declining to the cutoff level of positive antibody response may be 18.08 months, 18.83 months and 19.08 months after booster dose in three groups, respectively. Long-term immune persistence within 10 months after the second dose was associated with age<40, female, and history of influenza vaccination. All adverse reactions were mild after the booster injection. None of the participants were infected SARS-CoV-2 during the trial period. ConclusionsThe priming two-dose BBIBP-CorV vaccine with 0-28 days and 0-21 days schedule could lead a longer persistence of neutralizing antibody than 0-14 days schedule. Maintaining long-term immune persistence was also associated with age<40, female, and history of influenza vaccination. Regardless of priming two-doses vaccination regimens, a homologous booster dose led to a strong rebound in neutralizing antibody and might elicit satisfactory persistent immunity.
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Vaccination is urgently needed to prevent the global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here, we conducted a randomized, parallel, controlled clinical trial for assessment of the immunogenicity and safety of an inactivated SARS-CoV-2 vaccine, aiming to determine an appropriate vaccination interval for high-risk occupational population. Participants were randomly assigned to receive two doses of inactivated SARS-CoV-2 vaccine (4 {micro}g per dose) at an interval of either 14 days, 21 days or 28 days. The primary immunogenicity endpoints were neutralization antibody seroconversion and geometric mean titer (GMT) at 28 days after the second dose. Our results showed that the seroconversion rates (GMT [≥] 16) were all 100% in the three groups and the 0-21 and 0-28 groups elicited significantly higher SARS-CoV-2 neutralizing antibody level. All reported adverse reactions were mild. (Chinese Clinical Trial Registry: ChiCTR2100041705, ChiCTR2100041706)
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<p><b>OBJECTIVE</b>To explore factors influencing mortality rate of HIV/AIDS and to improve the effectiveness of antiretroviral therapy (ART).</p><p><b>METHODS</b>By means of retrospective cohort study and the AIDS control information system, HIV/AIDS case reports and antiviral treatment information of 4 cities in southern Shanxi province up to end of December 2012 were selected, to calculate the mortality rate and treatment coverage based on further data collected, along with analysis using the Cox proportional hazards survival regression.</p><p><b>RESULTS</b>4 040 cases confirmed of HIV/AIDS were included in this study. The average age was (36.0 ± 12.9) years, with 65.3% being male, 56.5% being married, 73.5% having junior high school education or lower, 58.4% being peasants, 54.3% with sexually transmitted infection (40.1% were heterosexual, 14.2% were homosexual), and 38.9% were infected via blood transmission (20.2% were former plasma donors, 16.2% blood transfusion or products recipients, 2.4% were injection drug users). Overall mortality decreased from 40.2 per 100 person/year in 2004 to 6.3 per 100 person/year in 2012, with treatment coverage concomitantly increasing from almost 14.8% to 63.4%. Cox proportional hazards survival regression was used on 4 040 qualified cases, demonstrating the top mortality risk factor was without antiretroviral therapy (RR = 14.9, 95% CI: 12.7-17.4). Cox proportional hazards survival regression was made on 1 938 cases of antiviral treatment, demonstrating that the mortality risk of underweight or obese before treatment was higher than those of normal and overweight cases (RR = 2.7, 95% CI: 1.6-4.5), and the mortality of those having a CD4(+) T-lymphocyte count ≤ 50 cells per µl before treatment was more than 50 cases (RR = 2.6, 95% CI: 1.5-4.5); Cox proportional hazards survival regression was made on 2 102 cases of untreated cases, demonstrating the mortality risk of those initially diagnosed as AIDS was higher than those initially diagnosed as HIV (RR = 3.4, 95% CI: 2.9-4.0).</p><p><b>CONCLUSION</b>The ART could successfully make lower HIV/AIDS mortality rate, indicating effective ART can further decrease mortality.</p>
