Effectiveness of COVID-19 vaccines against SARS-CoV-2 Omicron variants during two outbreaks from March to May 2022 in Quzhou, China.

Limited data are available on the effectiveness of COVID-19 vaccines used in China in real-world outbreaks - especially against Omicron variants in vaccinated individuals. Two outbreaks of SARS-CoV-2 Omicron variants - the first involving the sub-lineage BA.2 and the second the BA.1 variant - occurred in Quzhou. Infected people and their close contacts were divided according to vaccination status: unvaccinated, partially vaccinated, fully vaccinated, and boosted. The Cox proportional-hazard regression model was used to estimate the evolving hazard for vaccinated individuals after their first immunization. 138 people had been infected with the SARS-CoV-2 Omicron BA.2 variant and 13 with the BA.1 variant. Of the 151 infections, 99.34% (150/151) were mild or asymptomatic and 90.07% (136/151) were vaccine breakthrough cases. The total vaccine effectiveness (VE) of partial, full, and booster vaccinations during the two outbreaks was 47.4% (95%CI: 0-93.1%), 28.9% (95%CI: 0-60.2%), and 27.5% (95%CI: 0-58.3%). The VE of booster vaccination against the Omicron BA.1 variant was higher than that for the BA.2 variant. The cumulative hazard began to increase 220 days after the first immunization. The transmissibility of the Omicron BA.2 variant as for BA.1 did not increase in vaccinated individuals; booster vaccination after a primary course substantially increased protection. Our study found that the SARS-CoV-2 Omicron variant caused less severe illness and that the VE of boosters against the Omicron variant was less than 30%. Timely administration of the booster dose was important, especially for individuals aged over 80 years old.

Assessment of knowledge, attitudes, practices, and risk perceptions regarding COVID-19: a cross-sectional study from China.

Aim: To analyze the level of knowledge, attitudes, practices, and risk perception regarding COVID-19 among Chinese residents 1.5 years after the pandemic. Subject and methods: A cross-sectional study was carried out with both online and paper questionnaires. We included a variety of covariates that were characteristic-related factors such as age, gender, education level, and retirement status, as well as those closely associated with risk perception regarding COVID-19. Results: Participants (n = 3588), 53.49 ± 18.88 years old, from two provinces of China, of which 44.7% were male and 52.03% had a high school or greater level of education, answered the questions. More than 90% of participants had adequate background knowledge about COVID-19 and agreed or even strongly agreed with many attitude items related to the government's role in diagnosis, treatment, and dealing with COVID-19 infections. About three fifths of the participants reported fear of contracting COVID-19, but only a minority (18.63%) felt they were more susceptible than others. Respondents aged 45 years or younger were more likely to fear contracting the virus than those older than 45 years (adjusted OR = 1.464, 95% CI 1.196 to 1.794, P = 0.0002). High education level (adjusted OR = 1.503, 95% CI 1.187 to 1.904, P = 0.0007) and non-retired status (adjusted OR = 1.679, 95% CI 1.354 to 2.083, P < 0.0001) were associated with a higher perception of susceptibility to infection than others. Moreover, respondents who were not retired had a significantly reduced practice score (adjusted OR = 1.554, 95% CI 1.261 to 1.916, P < 0.0001). Age, retirement status, and education level were also associated with knowledge, attitude, and practice level. Conclusion: Our findings suggest that the public generally has trust in the COVID-19 vaccine and the government with regard to COVID-19 in China. We recommend that high-risk groups of communities, such as elders and patients with chronic diseases, be given greater consideration in the outbreaks. Health education campaigns combined with workplace preventive intervention should be aimed at improving COVID-19 knowledge and beliefs in order to encourage more optimistic attitudes and to maintain safe practices.

Comparing the pertussis antibody levels of healthy children immunized with four doses of DTap-IPV/Hib (Pentaxim) combination vaccine and DTaP vaccine in Quzhou, China.

Despite the high coverage of pertussis vaccines in high-income countries, pertussis resurgence has been reported in recent years, and has stimulated interest in the effects of vaccines and vaccination strategies. Immunoglobulin G (IgG) antibodies against pertussis toxoid (PT), filamentous hemagglutinin (FHA), and pertactin (PRN) after immunization with four doses of co-purified or component vaccines were determined by enzyme-linked immunosorbent assay (ELISA). Serological data of PT-IgG geometric mean concentrations (GMCs) over time since vaccination were used to fit the mathematical models. A total of 953 children were included in this study; 590 participants received four doses of the component acellular vaccine and 363 participants received four doses of the co-purified acellular vaccine. The GMCs and the seropositivity rate of pertussis IgG were significantly influenced by the production methods, and the immunogenicity of the component acellular vaccine was superior to that of the co-purified acellular vaccine. The fitted mathematical models for the component acellular vaccine and the co-purified acellular vaccine were Y=91.20e-0.039x and Y=37.71x-0.493, respectively. The initial GMCs of the component acellular vaccine was higher than that of the co-purified acellular vaccine, but both were similar at 72 months after immunization. Pertussis IgG levels waned over time after four doses of acellular pertussis vaccine, regardless of whether component or co-purified vaccine was used. The development and promotion of component acellular pertussis vaccines should be accelerated in China, and booster doses of pertussis vaccine in adolescents, adults, and pregnant women should be employed.