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Abstract Objectives: The aim of the present study was to evaluate if neutralizing antibody responses induced by infection with the SARS-CoV-2 strain that was dominant at the beginning of the pandemic or by the Gamma variant was effective against the Omicron variant. Methods: Convalescent sera from 109 individuals, never exposed to a SARS-CoV-2 vaccine, who had mild or moderate symptoms not requiring hospitalization following either a documented SARS-CoV-2 ancestral strain infection or a Gamma variant infection, were assayed for in vitro neutralizing antibody activity against their original strains and the Omicron variant. Results: Following an infection with the ancestral strain, 56 (93.3%), 45 (77.6%) and 1 (1.7%) serum sample were positive for neutralizing antibodies against the ancestral, Gamma variant, and Omicron variant, respectively. After infection with the Gamma variant, 43 (87.8%) and 2 (4.1%) sera were positive for neutralizing antibodies against the Gamma and Omicron variants, respectively. Conclusions: Neutralizing antibodies generated following mild or moderate infection with the SARS-CoV-2 ancestral strain or the Gamma variant are not protective against the Omicron variant. HIGHLIGHTS Individuals previously infected with SARS-CoV-2 ancestral strain do not develop neutralizing antibodies against the Omicron variant. Omicron variant escapes immune response after SARS CoV-2 previous infection with the SARS CoV-2 Gamma variant. Individuals previously infected with SARS-CoV-2 ancestral strain or with SARS-CoV-2 Gamma variant will likely have little protection if subsequently exposed to the Omicron variant.
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Objective@#To observe the efficacy and safety related measures by blocking mother-to-child transmission of hepatitis B virus with high viral load and HBeAg positivity during pregnancy in Guizhou province.@*Methods@#Outpatient and inpatient cases of the Department of Infectious Diseases and Obstetrics of Guizhou Medical University Affiliated Hospitals from May 2016 to July 2017 were retrospectively divided into intervention group, non-intervention group and non- hepatitis B pregnant women group; with 75 cases in each group. HBsAg and HBeAg were positive in the intervention group. Pregnant women with HBV DNA ≥106 IU/ml were treated with anti-HBV therapy for 24 to 28 weeks of gestation until delivery. According to oral drugs, they were divided into tenofovir (TDF) group or telbivudine (LDT) group, non-intervention group (HBsAg and HBeAg positive), HBV DNA positive pregnant women, pregnant women with no anti-HBV drugs, non-hepatitis B pregnant women (normal pregnant women without HBV infection). Infants and young children born to the three groups of women were immunized with the national viral hepatitis B action plan. The gestational weeks and Apgar scores at birth, delivery mode, feeding mode, sex and 7-months-old age were observed and counted. Serum hepatitis B markers (HBVM) and HBV DNA were quantitatively detected. HBVM was detected by time-resolved fluorescence immunoassay (TRFIA), and HBV DNA was detected by real-time PCR (FQ-PCR). The changes of liver parameters, HBsAg, HBeAg, HBV DNA, adverse drug reactions and treatment response of pregnant intervention group before medication (12-24 weeks of gestation), 4 weeks of medication (28-32 weeks of gestation), 36-40 weeks of gestation (36-40 weeks of gestation) were statistically calculated. A t-test was used to compare the data between the measurements. Data measurements within the groups were analyzed using rank -sum test.@*Results@#In the intervention group, therapeutic medications showed no differences in demographic and clinical characteristics between TDF group and LDT group, including liver parameters, HBsAg, HBeAg and log10HBV DNA level. Compared with pre-treatment (TDF group: 4.84 ± 2.01; LDT group: 5.08 ± 1.99), TDF and LDT were significantly lower at the end of pregnancy (TDF group: 3.06 ± 0.66; LDT group: 3.51 ± 1.20). P < 0.05); and the treatment response rate was 100%. There were no serious adverse events in the intervention group. Infants and young children (7-months-old) in the intervention group had negative HBsAg, HBeAg and HBV DNA. The mother-to-child transmission rate of HBV was zero, with blocking rate of 100%. In addition, both infants and young children had different degrees of hepatitis B protective antibodies (anti-HBs, M: 144.33), and their antibody titers were higher than that of non-intervention group (anti-HBs, M: 65.91) and non-hepatitis B pregnant women (anti-HBs, M: 58.43). The difference was statistically significant (P < 0.05), and there was no significant correlation between the use of antiviral and the way of delivery and feeding. Outcomes of mother-to-child transmission of HBV infection in infants and young children (7-months-old) delivered by three groups of pregnant women in the non-intervention groups had 20.0% (15/75)/ 17.3% (13/75) HBsAg/HBeAg positivity rate, and 17.3% (13/75) HBV DNA positivity rate. Overall, mother-to-child transmission rate of HBV infection was 20% (15/75). Furthermore, the relationship between mother's HBV DNA load and infant HBV infection in the non-intervention group showed mother's HBV DNA ≥106 IU/ml.@*Conclusion@#In the non-intervention group, mother-to-child transmission of HBV occurred, and infected mothers HBV DNA was ≥106 IU/ml before delivery. This suggests that HBeAg positive and high load HBV DNA replication were independent risk factors for mother-to-child transmission of hepatitis B. Therefore, prenatal drug intervention and postpartum standard immune blockade are necessary for high-risk pregnant women with hepatitis B to achieve zero mother-to-child transmission of hepatitis B in real- clinical practice.
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Serologic data on diseases that are preventable by vaccines are necessary to evaluate the success of immunization programs and to identify susceptible subgroups. In the present study, we determined serum IgG levels against diphtheria toxin of military and civilian blood donors (N = 75; 69.3 percent males and 30.7 percent females) aged 18-64 years, from the Brazilian Army Biology Institute, Rio de Janeiro, using a commercial diphtheria kit (Diphtheria IgG ELISA; IBL, Germany). Most (63 percent) unprotected military donors were from the older age group of 41 to 64 years. In contrast, the majority (71 percent) of young military donors (18 to 30 years) were fully protected. About half of the military donors aged 31 to 40 years were protected against diphtheria. Among the civilians, about 50 percent of persons aged 18 to 30 years and 31 to 40 years had protective antibody levels against diphtheria as also did 64 percent of individuals aged 41 to 64 years. All civilians had a similar antibody response (geometric mean = 0.55 IU/mL) independent of age group. Military donors aged 18-30 years had higher IgG levels (geometric mean = 0.82 IU/mL) than military donors of 41-64 years (geometric mean = 0.51 IU/mL; P > 0.05). In conclusion, the existence of a considerable proportion of susceptible adults supports the position that reliable data on the immune status of the population should be maintained routinely and emphasizes the importance of adequate immunization during adulthood.