Search

BackgroundThe coronavirus disease 2019 (COVID-19) is a severe acute respiratory disease that poses a continuous threat to global public health. Many non-pharmacological interventions (NPIs) have been implemented to control the COVID-19 pandemic since the beginning. The aim of this study was to assess the impact of various NPIs on COVID-19 mortality during pre-vaccination and vaccination periods.MethodsThe COVID-19 data used in this study comes from Our World in Data, we used the Oxford Strict Index (OSI) and its five combination interventions as independent variables. The COVID-19 mortality date (MRT) was defined as a date when daily rate of 0.02 COVID-19 deaths per 100,000 population in a country was reached, and the COVID-19 vaccination date (VRT) was defined as people vaccinated reaching 70%. Linear regression and random forest models were used to estimate the impact of various NPI implementation interventions during pre-vaccination and vaccination periods. The performance of models was assessed among others with Shapley Additive Explanations (SHAP) explaining the prediction capability of the model.ResultsDuring the pre-vaccination period, the various NPIs had strong protective effect. When the COVID-19 MRT was reached, for every unit increase in OSI, the cumulative mortality as of June 30, 2020 decreased by 0.71 deaths per 100,000 people. Restrictions in travel (SHAP 1.68) and cancelation of public events and gatherings (1.37) had major reducing effect on COVID-19 mortality, while staying at home (0.26) and school and workplace closure (0.26) had less effect. Post vaccination period, the effects of NPI reduced significantly: cancelation of public events and gatherings (0.25), staying at home (0.22), restrictions in travel (0.14), and school and workplace closure (0.06).ConclusionContinued efforts are still needed to promote vaccination to build sufficient immunity to COVID-19 in the population. Until herd immunity is achieved, NPI is still important for COVID-19 prevention and control. At the beginning of the COVID-19 pandemic, the stringency of NPI implementation had a significant negative association with COVID-19 mortality; however, this association was no longer significant after the vaccination rate reached 70%. As vaccination progresses, “cancelation of public events and gatherings” become more important for COVID-19 mortality.

Objective: To investigate factors influencing commitment to human papilloma virus (HPV) vaccination and prior vaccination among female college students in northern Taiwan. Methods: A quota sample of 400 female college students was recruited from nine colleges in northern Taiwan during March 2013. Of these, 398 completed the self administered questionnaire which was designed based on the health promotion model. Results: The results showed that factors associated with prior vaccination behavior were family history of gynecologic malignancy, ever being advised to get HPV vaccination, perceived barriers of action and perceived self-efficacy. Predictors for commitment to HPV vaccination in the next 6 months were the cost of vaccination, ever being advised to get HPV vaccination, perceived self-efficacy and situational influences. Perceived self-efficacy was significantly influenced by relationship status, past receipt of a recommendation for HPV vaccination and level of knowledge about HPV. Conclusion: When formulating vaccination policies, governmental or medical institutions should include these factors to promote vaccination. [ABSTRACT FROM AUTHOR]

Enterovirus A71 (EV-A71) can induce severe neurological complications and even fatal encephalitis in children, and it has caused several large outbreaks in Taiwan since 1998. We previously generated VP1 codon-deoptimized (VP1-CD) reverse genetics (rg) EV-A71 viruses (rgEV-A71s) that harbor a high-fidelity (HF) 3D polymerase. These VP1-CD-HF rgEV-A71s showed lower replication kinetics in vitro and decreased virulence in an Institute of Cancer Research (ICR) mouse model of EV-A71 infection, while still retaining their antigenicity in comparison to the wild-type virus. In this study, we aimed to further investigate the humoral and cellular immune responses elicited by VP1-CD-HF rgEV-A71s to assess the potential efficacy of these EV-A71 vaccine candidates. Following intraperitoneal (i.p.) injection of VP1-CD-HF rgEV-A71s in mice, we observed a robust induction of EV-A71-specific neutralizing IgG antibodies in the antisera after 21 days. Splenocytes isolated from VP1-CD-HF rgEV-A71s-immunized mice exhibited enhanced proliferative activities and cytokine production (IL-2, IFN-, IL-4, IL-6, and TNF-a) upon re-stimulation with VP1-CD-HF rgEV-A71, as compared to control mice treated with adjuvant only. Importantly, administration of antisera from VP1-CD-HF rgEV-A71s-immunized mice protected against lethal EV-A71 challenge in neonatal mice. These findings highlight that our generated VP1-CD-HF rgEV-A71 viruses are capable of inducing both cellular and humoral immune responses, supporting their potential as next-generation EV-A71 vaccines for combating EV-A71 infection. IMPORTANCE EV-A71 can cause severe neurological diseases and cause death in young children. Here, we report the development of synthetic rgEV-A71s with the combination of codon deoptimization and high-fidelity (HF) substitutions that generate genetically stable reverse genetics (rg) viruses as potential attenuated vaccine candidates. Our work provides insight into the development of low-virulence candidate vaccines through a series of viral genetic editing for maintaining antigenicity and genome stability and suggests a strategy for the development of an innovative next-generation vaccine against EV-A71. [ABSTRACT FROM AUTHOR]

Enterovirus A71 (EV-A71) is the major pathogen which causes hand-foot-and-mouth disease (HFMD) which occasionally results in severe neurological complications. In this study, we developed four EV-A71 (rgEV-A71) strains by reverse genetics procedures as possible vaccine candidates. The four rgEV-A71 viruses contained various codon deoptimized VP1 capsid protein (VP1-CD) showed similar replication rate and antigenicity to wild-type virus, while a fifth virus, rg4643C4VP-CD, was unable to form plaques, but was still able to examined by TCID50 titers which were similar to the others, thus indicating the effect of CD on plaque formation. However, the genome stability showed that there were some mutations which appeared during just one passage of the VP1-CD viruses. Thus, we further constructed VP1-CD rgEV-A71 containing high-fidelity determinants in 3D polymerase (CD-HF) and the number of mutations in CD-HF rgEV-A71 was shown to have decreased. The CD-HF viruses showed less virulence than the parental strain in mice infection model. After 14 days post-immunization, antibody titers had increased in mice infected with CD-HF viruses. The mouse antisera showed similar neutralizing antibody titers against various CD-HF viruses and different genotypes of EV-A71. The study demonstrates proof-of-concept that VP1 codon deoptimization combined with high-fidelity 3D polymerase decreased EV-A71 mutations and virulence in mice but retained their antigenicity, which may be a good 46 candidate for next generation EV-A71 vaccine development. [ABSTRACT FROM AUTHOR]