Neutralizing Antibody Responses against Five SARS-CoV-2 Variants and T Lymphocyte Change after Vaccine Breakthrough Infections from the SARS-CoV-2 Omicron BA.1 Variant in Tianjin, China: A Prospective Study.

Objective: To investigate whether Omicron BA.1 breakthrough infection after receiving the SARS-CoV-2 vaccine could create a strong immunity barrier. Methods: Blood samples were collected at two different time points from 124 Omicron BA.1 breakthrough infected patients and 124 controls matched for age, gender, and vaccination profile. Live virus-neutralizing antibodies against five SARS-CoV-2 variants, including WT, Gamma, Beta, Delta, and Omicron BA.1, and T-lymphocyte lymphocyte counts in both groups were measured and statistically analyzed. Results: The neutralizing antibody titers against five different variants of SARS-CoV-2 were significantly increased in the vaccinated population infected with the Omicron BA.1 variant at 3 months after infection, but mainly increased the antibody level against the WT strain, and the antibody against the Omicron strain was the lowest. The neutralizing antibody level decreased rapidly 6 months after infection. The T-lymphocyte cell counts of patients with mild and moderate disease recovered at 3 months and completely returned to the normal state at 6 months. Conclusion: Omicron BA.1 breakthrough infection mainly evoked humoral immune memory in the original strain after vaccination and hardly produced neutralizing antibodies specific to Omicron BA.1. Neutralizing antibodies against the different strains declined rapidly and showed features similar to those of influenza. Thus, T-lymphocytes may play an important role in recovery.

[Introduction of pertussis surveillance system and evaluation of its operational effect in Tianjin].

The pertussis surveillance system has been established since 2009 in Tianjin, and continuously improved over the past 10 years. This system determines the definition and classification of pertussis, establishes simple and feasible sampling methods and laboratory detection methods in clinical practice, standardizes the report management of pertussis cases and the treatment of epidemic situations. After the implementation of the surveillance system, the number of reported pertussis cases increased from 26 in 2009 to 802 in 2017, the number of diagnosed cases increased from 19 in 2009 to 662 in 2017, the reported incidence rate of pertussis increased from 0.16/100 000 in 2009 to 4.28/100 000 in 2017, and the number of medical institutions of reporting perutssis cases increased from 2 in 2009 to 53 in 2017. The specimen collection rate of the reported cases reached up to 93.66%. These results show that the sensitivity of pertussis surveillance has been improved and show that the data from the surveillance system may reflect more precisely the epidemical characteristics of perutssis in Tianjin.

A novel point-of-care oral anti-HCV assay: Is it reliable for screening hepatitis C virus infection in the era of direct-acting antivirals?

Recent advance in the direct-acting antivirals (DAAs) offers the potentials to eradicate hepatitis C virus (HCV) worldwide and makes universal screening more urgent. A point-of-care (POC) oral anti-HCV assay, the Fortune assay, was developed and its performance was evaluated. Individuals with or without HCV infection were recruited in three Centers. Paired oral and serum samples were tested using the Fortune and InTec anti-HCV assays. The Kehua serum anti-HCV assay served as a supplemental test to verify the discordant results. Some oral samples were also tested using the OraQuick anti-HCV assay. Furthermore, the Fortune assay results were compared with the documented RNA results. Sensitivity, specificity, and accuracy of the Fortune assay was 93.11%, 98.48%, and 96.58%, respectively (n = 1,022). Consistency between the Fortune and OraQuick assays was 96.35% (264/274); the Fortune assay detected additional 8 positive oral samples missed by the OraQuick assay. The Fortune assay demonstrated a 97.46% (115/118) positivity among the viremic patients. Furthermore, its sensitivity was HCV genotype independent. In conclusion, the Fortune assay was highly specific and accurate. It had comparable sensitivity as the serum assays for the diagnosis of active HCV infection. It provides a completely non-invasive and reliable tool for HCV screening in the DAA era.

Measles Virus IgG Avidity Assay for Use in Identification of Measles Vaccine Failures in Tianjin, China.

OBJECTIVE: To identify measles vaccine failures in Tianjin, China using a measles virus IgG avidity assay. METHODS: The China Information System for Disease Control and Prevention (CISDCP) was used to collect information about measles cases and blood specimens in Tianjin from 2013 to 2015. Measlesspecific IgM and IgG antibodies were detected using Enzyme-Linked Immunosorbent Assay (ELISA). Avidity testing for measles IgG was performed using a commercial enzyme immunoassay (EIA). RESULTS: A total of 284 confirmed measles cases were identified. Of this total, 262 (92.25%) were in patients aged ⪖ 20 years. High avidity was exhibited in 172 (60.56%) cases, while 80 (28.17%) cases demonstrated low avidity. High avidity was detected in only 21.43% of cases in patients aged < 1 year. The proportion of high avidity increased with age, and was significantly higher in patients aged 30-39 years at 70.07% (χ2 = 17.27, P = 0.002). Of the 52 measles cases in patients with a history of vaccinations, 41 (78.85%) cases showed high avidity, indicating secondary vaccine failures (SVF). In these vaccinations, there was no significant difference (P > 0.05) in clinical severity between high avidity and low avidity cases. However, regardless of vaccination status, clinical severity was significantly lower in high avidity cases (P < 0.001) than in low avidity cases. The percentages of positive measles IgM results in high avidity and low avidity cases were 66.28% and 91.25%, respectively. Geometric Mean Concentration (GMC) was significantly lower in high avidity cases at 33.73 U/mL, compared to 166.07 U/mL in low avidity cases. CONCLUSION: Low clinical severity and inconclusive IgM antibody results are more likely in high avidity measles cases. Measles cases were more common in adults. Therefore, a further dose of vaccines should be recommended for 30-39 years in Tianjin..

Effectiveness of 10-year vaccination (2001-2010) on Hepatitis A in Tianjin, China.

Vaccination is an effective strategy to prevent and control the transmission of hepatitis A. Hepatitis A immunization program has been taken into effect since 2001 in Tianjin, China. This study evaluated the effectiveness of strategies in the prevention and control of hepatitis A. Data of serological survey, annual hepatitis A incidence, immunization coverage and the positive rate of hepatitis A IgG before and after the immunization program in residents under 15 years old were used to do the analysis. The results indicated that hepatitis A vaccine induced a striking decrease of hepatitis A incidence and a significant increase in the positive rate of anti-HAV IgG among the children younger than 15 years old. Hepatitis A vaccination in children was proved to be effective in the prevention and control of hepatitis A in Tianjin, China.

[Evaluation on the role of hepatitis A vaccine in the prevention and control of hepatitis A in Tianjin city].

OBJECTIVE: To evaluate the effects of prevention and control strategies on hepatitis A. METHODS: Surveillance data on hepatitis A from 1990 to 2006 in Tianjin was analyzed, and the coverage rate of hepatitis A vaccine among targeted population was estimated, to compare the anti-HAV IgG level of children younger than 15 years old in 1999 and in 2005. RESULTS: Results showed that a) the morbidity of hepatitis A decreased from 25.26/10(5) in 1990 to 0.82/10(5) in 2006; b) the ratio of hepatitis A in viral hepatitis decreased from 30.43% in 1990 to 1.05% in 2006; c) the estimated coverage rate was 72.7%; d) the positive rate of anti-HAV among children younger than 15 years old in 2005 was distinctly higher than that in 1999. CONCLUSION: Positive results showed that it was successful to use hepatitis A vaccine as the strategy to prevent and control hepatitis A in the past five years in Tianjin.