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BackgroundLimited data are available on effectiveness of inactivated and Ad5-nCoV COVID-19 vaccines in real-world use - especially against Omicron variants in SARS-CoV-2 infection-naive population. During an outbreak in Shanghais SARS-CoV-2 infection-naive population, we evaluated vaccine effectiveness (VE) against Omicron infection, severe or critical COVID-19, and COVID-19-related death. MethodsA matched case-control study was conducted among people aged [≥]3 years between 2 December 2021 through 13 May 2022. Cases were SARS-CoV-2 infected individuals, individuals with severe/critical COVID-19, or COVID-19-related deaths. Controls were selected from consecutively test negative individuals at the same time as cases were diagnosed and were exact-matched on year-of-age, gender, birthplace, illness onset date, and residency district in ratios of 1:1 with infected individuals and 4:1 with severe/critical COVID-19 and COVID-19-related deaths. ResultsOur study included 612597 documented SARS-CoV-2 infections, among which 1485 progressed to severe or critical illness and 568 died. Inactivated vaccine was 16.3% (95% CI: 15.4%-17.2%) effective against infection, 88.6% (95% CI: 85.8%-90.9%) effective against severe/critical COVIID-19 and 91.7% (95% CI: 86.9%-94.7%) against COVID-19 death. Ad5-vectored vaccine was 13.2% (95% CI: 10.9%-15.5%) effective against infection and 77.9% (95% CI: 15.6%-94.2%) effective against severe/critical COVIID-19. Booster vaccination with inactivated vaccines enhanced protection against severe COVID-19 (92.7%, 95% CI: 90.1%-94.6%) and COVID-19 death (95.9%, 95% CI: 91.4%-98.1%). Inactivated VE against infection began to wane 12 weeks after the last dose but two- and three-dose sustained high protection levels (>80%) against severe/critical illness and death. ConclusionsOur real-world study found high and durable two- and three-dose inactivated VE against Omicron-associated severe/critical illness and death across all age groups, but lower effectiveness against Omicron infection. High direct protection from severe/fatal Omicron COVID-19 provided by inactivated vaccines, and a consequent potential reduction in health-care utilization, reinforces the critical importance of full-series vaccination and timely booster dose administration for all eligible individuals.
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Objective@#To evaluate the immunogenicity of different strains of inactivated poliomyelitis vaccines (IPV) by sequential program.@*Methods@#This parallel-group controlled trial was conducted in immunization clinics in Shanghai from March 2016 to September 2017. Sabin strains inactivated poliomyelitis vaccines (sIPV), WPV strains inactivated poliomyelitis vaccines (wIPV) and live poliomyelitis Type Ⅰ Type Ⅲ vaccine (bOPV) as the investigational vaccine were used at 2, 3, 4 months old in 325 infants in Shanghai. Infants vaccinated by four sequential program were divided into 4 groups: sIPV+sIPV+bOPV, sIPV+wIPV+bOPV, wIPV+sIPV+bOPV and wIPV+wIPV+bOPV. A total of 230 investigators′ blood samples were collected before primary immunization and 163 investigators′ blood samples were collected after primary immunization. A total of 151 investigators (36, 44, 30 and 41 in each group) finished primary immunization and blood sampling before and after the primary immunization. The geometric mean titer (GMT) of poliovirus typesⅠ and Ⅲ neutralizing antibody was tested and calculated, and the positive results of antibody before and after primary immunization were analyzed.@*Results@#Among the 151 investigators, the age were (2.27±0.61) months and birth weight were (3.27±0.43) kg, and 70 were male. The positive rates of typeⅠwas 98.68% (149 cases), and type Ⅲ was 97.35% (147 cases); the number of investigators tested in each group was 36, 44, 30 and 41, respectively; the positive rates of typeⅠwas 97.22% (35 cases), 100.00% (44 cases), 96.67% (29 cases) and 100.00% (41 cases) (P=0.345); the positive rates of type Ⅲ were 97.22% (35 cases), 95.45% (42 cases), 96.67% (29 cases) and 100.00% (41 cases) (P=0.614).@*Conclusion@#Using sIPV and wIPV simultaneously or alternately for sequential immunization of poliomyelitis vaccines showed good immunogenicity for infants at appropriate age.
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Objective@#To evaluate the safety of population based sequential vaccination schedule of inactivated poliovirus vaccines prepared with different strains.@*Methods@#This randomized, parallel-group controlled trial was conducted from March, 2017 to May, 2018, in Shanghai. Adverse reaction data of Sabin strain inactivated polio vaccine (sIPV), wild strains inactivated polio vaccines (wIPV) and bivalent types Ⅰ and Ⅲ oral poliomyelitis vaccine (bOPV) were systematically collected through active observation in 1 917 infants in Shanghai after the vaccination at 2, 3, 4 months old. The eligible infants aged 2 months were divided into 4 groups: ①sIPV+sIPV+bOPV group; ②sIPV+wIPV+bOPV group; ③wIPV+sIPV+bOPV group; ④wIPV+wIPV+bOPV group.@*Results@#The incidence of adverse reaction 30 days later after 3 basic dose vaccinations was 16.79% (946/5 633). No serious adverse reaction was reported. Local and systemic reactions were mainly mild. Common local reactions were pain, erythema, cutaneous nodule, etc.; and common systemic reactions were abnormal crying, drowsiness, diarrhea and appetite lost, etc.. The incidence of local reactions 30 days later after 3 basic dose vaccinations was 1.65% (93/5 633), and the incidence rates of grade 1-3 reactions were1.26% (71/5 633), 0.21% (12/5 633) and 0.20% (11/5 633) respectively. The incidence rate of systemic reactions 30 days later after 3 basic vaccinations was 15.14% (853/5 633), and the incidence rates of grade 1-3 reactions were 11.33% (638/5 633), 3.18% (179/5 633) and 0.64% (36/5 633) respectively. There were no significant differences in the rate of grade 3 reaction among different groups (χ2=4.17, P=0.24).@*Conclusions@#No severe adverse reactions related to sequential vaccination of different strain inactivated polio vaccines were observed, most of reactions were mild and all of them were cured. It is safe to use sIPV and wIPV simultaneously or alternately for childhood sequential vaccination.
