Follow-Up and Comparative Assessment of SARS-CoV-2 IgA, IgG, Neutralizing, and Total Antibody Responses After BNT162b2 or mRNA-1273 Heterologous Booster Vaccination.

BACKGROUND: Priming with ChAdOx1 followed by heterologous boosting is considered in several countries. Nevertheless, analyses comparing the immunogenicity of heterologous booster to homologous primary vaccination regimens and natural infection are lacking. In this study, we aimed to conduct a comparative assessment of the immunogenicity between homologous primary vaccination regimens and heterologous prime-boost vaccination using BNT162b2 or mRNA-1273. METHODS: We matched vaccinated naïve (VN) individuals (n = 673) with partial vaccination (n = 64), primary vaccination (n = 590), and primary series plus mRNA vaccine heterologous booster (n = 19) with unvaccinated naturally infected (NI) individuals with a documented primary SARS-CoV-2 infection (n = 206). We measured the levels of neutralizing total antibodies (NTAbs), total antibodies (TAbs), anti-S-RBD IgG, and anti-S1 IgA titers. RESULTS: Homologous primary vaccination with ChAdOx1 not only showed less potent NTAb, TAb, anti-S-RBD IgG, and anti-S1 IgA immune responses compared to primary BNT162b2 or mRNA-1273 vaccination regimens (p < 0.05) but also showed ~3-fold less anti-S1 IgA response compared to infection-induced immunity (p < 0.001). Nevertheless, a heterologous booster led to an increase of ~12 times in the immune response when compared to two consecutive homologous ChAdOx1 immunizations. Furthermore, correlation analyses revealed that both anti-S-RBD IgG and anti-S1 IgA significantly contributed to virus neutralization among NI individuals, particularly in symptomatic and pauci-symptomatic individuals, whereas among VN individuals, anti-S-RBD IgG was the main contributor to virus neutralization. CONCLUSION: The results emphasize the potential benefit of using heterologous mRNA boosters to increase antibody levels and neutralizing capacity particularly in patients who received primary vaccination with ChAdOx1.

Seroepidemiological assessment of SARS-CoV-2 vaccine responsiveness and associated factors in the vaccinated community of the Casablanca-Settat Region, Morocco.

Assessing the prevalence of SARS-CoV-2 IgG positivity through population-based serological surveys is crucial for monitoring COVID-19 vaccination efforts. In this study, we evaluated SARS-CoV-2 IgG positivity within a provincial cohort to understand the magnitude of the humoral response against the SARS-CoV-2 vaccine and to inform evidence-based public health decisions. A community-based cross-sectional seroprevalence study was conducted, involving 10,669 participants who received various vaccines (two doses for BBIBP-CorV/Sinopharm, Covishield vaccine, and Pfizer/BioNTech, and one dose for Johnson & Johnson's Janssen COVID-19 vaccine). The study spanned 16 provinces in the Casablanca-Settat region from February to June 2022, during which comprehensive demographic and comorbidity data were collected. We screened samples for the presence of IgG antibodies using the SARS-CoV-2 IgG II Quant assay, which quantifies antibodies against the receptor-binding domain (RBD) of the spike (S) protein, measured on the Abbott Architect i2000SR. The overall crude seroprevalence was 96% (95% CI: 95.6-96.3%), and after adjustment for assay performance, it was estimated as 96.2% (95% CI: 95.7-96.6). The adjusted overall seroprevalences according to vaccine brands showed no significant difference (96% for BBIBP-CorV/Sinopharm, 97% for ChAdOx1 nCoV-19/Oxford/AstraZeneca, 98.5% for BNT162b2/Pfizer-BioNTech, and 98% for Janssen) (p = 0.099). Participants of older age, female sex, those with a history of previous COVID-19 infection, and those with certain chronic diseases were more likely to be seropositive among ChAdOx1 nCoV-19/Oxford/AstraZeneca and BBIBP-CorV/Sinopharm vaccinee groups. Median RBD antibody concentrations were 2355 AU/mL, 3714 AU/mL, 5838 AU/mL, and 2495 AU/mL, respectively, after two doses of BBIBP-CorV/Sinopharm, ChAdOx1 nCoV-19/Oxford/AstraZeneca, BNT162b2/Pfizer-BioNTech, and after one dose of Janssen (p < 0.0001). Furthermore, we observed that participants vaccinated with ChAdOx1 nCoV-19/Oxford/AstraZeneca and BBIBP-CorV/Sinopharm with comorbid chronic diseases exhibited a more pronounced response to vaccination compared to those without comorbidities. In contrast, no significant differences were observed among Pfizer-vaccinated participants (p > 0.05). In conclusion, our serosurvey findings indicate that all four investigated vaccines provide a robust humoral immune response in the majority of participants (more than 96% of participants had antibodies against SARS-CoV-2). The BNT162b2 vaccine was found to be effective in eliciting a strong humoral response compared to the other three vaccines. However, challenges still remain in examining the dynamics and durability of immunoprotection in the Moroccan context.

Risk assessment and antibody responses to SARS-CoV-2 in healthcare workers.

Background: Preventing infection in healthcare workers (HCWs) is crucial for protecting healthcare systems during the COVID-19 pandemic. Here, we investigated the seroepidemiology of SARS-CoV-2 in HCWs in Norway with low-transmission settings. Methods: From March 2020, we recruited HCWs at four medical centres. We determined infection by SARS-CoV-2 RT-PCR and serological testing and evaluated the association between infection and exposure variables, comparing our findings with global data in a meta-analysis. Anti-spike IgG antibodies were measured after infection and/or vaccination in a longitudinal cohort until June 2021. Results: We identified a prevalence of 10.5% (95% confidence interval, CI: 8.8-12.3) in 2020 and an incidence rate of 15.0 cases per 100 person-years (95% CI: 12.5-17.8) among 1,214 HCWs with 848 person-years of follow-up time. Following infection, HCWs (n = 63) mounted durable anti-spike IgG antibodies with a half-life of 4.3 months since their seropositivity. HCWs infected with SARS-CoV-2 in 2020 (n = 46) had higher anti-spike IgG titres than naive HCWs (n = 186) throughout the 5 months after vaccination with BNT162b2 and/or ChAdOx1-S COVID-19 vaccines in 2021. In a meta-analysis including 20 studies, the odds ratio (OR) for SARS-CoV-2 seropositivity was significantly higher with household contact (OR 12.6; 95% CI: 4.5-35.1) and occupational exposure (OR 2.2; 95% CI: 1.4-3.2). Conclusion: We found high and modest risks of SARS-CoV-2 infection with household and occupational exposure, respectively, in HCWs, suggesting the need to strengthen infection prevention strategies within households and medical centres. Infection generated long-lasting antibodies in most HCWs; therefore, we support delaying COVID-19 vaccination in primed HCWs, prioritising the non-infected high-risk HCWs amid vaccine shortage.

Echocardiographic Assessment Of Left Ventricular Function After COVID-19 Vaccination In Adults.

Objectives: To assess left ventricular function by conventional and speckle tracking echocardiography in subjects having received coronavirus disease-2019 vaccine. Method: The cohortstudy was conducted from April 2021 to April 2022 at the Department of Cardiology, Kafrelsheikh University Hospital, Egypt, and comprised adults of either gender who had received coronavirus disease-2019 vaccine. Detailed history was noted before clinical assessment, electrocardiogram and echocardiography, which were done at baseline and after two weeks of the last vaccine dose. Apical 4, apical 3 and apical 2 strains were obtained to get the global longitudinal strain. Data was analysed using SPSS 20. RESULTS: Of the 100 subjects, 50(50%) each were males and females. The overall mean age was 39.20±14.57 years. There were 16(16%) subjects with diabetes mellitus and 21(21%) with hypertension. Regarding vaccine distribution, 34(34%) had received AstraZeneca AZD1222, 31(31%) had BioNTech Pfizer vaccine BNT162B2 and 35(35%) had Sinopharm Beijing Institute of Biological Products BBIBP-CorV. The global longitudinal strain before and after vaccination did not show a significant difference (p<0.063). There was no significant variation in global longitudinal strain between the various vaccination types (p=0.584). CONCLUSIONS: The studied vaccines had similarly acceptable safety profiles regarding left ventricular functions.

Serious adverse event following immunization and thromboembolic events associated with COVID19 vaccination: An analysis of nationwide causality assessment from India.

BACKGROUND: Vaccines against the COVID-19 pandemic were introduced in late 2020. The present study has been conducted to study the serious Adverse Events Following Immunization (AEFIs) reported for COVID-19 vaccines from India. METHODS: Secondary data analysis of the causality assessment reports for the 1112 serious AEFIs published by the Ministry of Health & Family Welfare, Government of India, was conducted. For the current analysis, all the reports published till 29.03.2022 were included. The primary outcome variables analyzed were the consistent causal association and the thromboembolic events. RESULTS: The majority of the serious AEFIs assessed were either coincidental (578, 52%) or vaccine product related (218, 19.6%). All the serious AEFIs were reported among the Covishield (992, 89.2%) and COVAXIN (120, 10.8%) vaccines. Among these, 401 (36.1%) were deaths, and 711 (63.9%) were hospitalized and recovered. On adjusted analysis, females, the younger age group and non-fatal AEFIs showed a statistically significant consistent causal association with COVID-19 vaccination. Thromboembolic events were reported among 209 (18.8%) of the analyzed participants, with a significant association with higher age and case fatality rate. CONCLUSION: Deaths reported under serious AEFIs were found to have a relatively lower consistent causal relationship with the COVID-19 vaccines than the recovered hospitalizations in India. No consistent causal association was found between the thromboembolic events and the type of COVID-19 vaccine administered in India.

A Brighton Collaboration standardized template with key considerations for a benefit/risk assessment for the Medigen COVID-19 protein vaccine.

The Brighton Collaboration Benefit-Risk Assessment of VAccines by TechnolOgy (BRAVATO) Working Group has prepared standardized templates to describe the key considerations for the benefit-risk assessment of several vaccine platform technologies, including protein subunit vaccines. This article uses the BRAVATO template to review the features of the MVC-COV1901 vaccine, a recombinant protein subunit vaccine based on the stabilized pre-fusion SARS-CoV-2 spike protein S-2P, adjuvanted with CpG 1018 and aluminum hydroxide, manufactured by Medigen Vaccine Biologics Corporation in Taiwan. MVC-COV1901 vaccine is indicated for active immunization to prevent COVID-19 caused by SARS-CoV-2 in individuals 12 years of age and older. The template offers details on basic vaccine information, target pathogen and population, characteristics of antigen and adjuvant, preclinical data, human safety and efficacy data, and overall benefit-risk assessment. The clinical development program began in September 2020 and based on demonstration of favorable safety and immunogenicity profiles in 11 clinical trials in over 5,000 participants, it has been approved for emergency use based on immunobridging results for adults in Taiwan, Estwatini, Somaliland, and Paraguay. The main clinical trials include placebo-controlled phase 2 studies in healthy adults (CT-COV-21), adolescents (CT-COV-22), and elderly population (CT-COV-23) as well as 3 immunobridging phase 3 trials (CT-COV-31, CT-COV-32, and CT-COV-34) in which MVC-COV1901 was compared to AZD1222. There are also clinical trials studying MVC-COV1901 as homologous and heterologous boosters (CT-COV-24 and CT-COV-25). The totality of evidence based on ∼3 million vaccinees to date includes a mostly clean safety profile, with adverse events mostly being mild and self-limiting in both clinical development and post-marketing experience, proven immunogenic response, and real-world effectiveness data. The immunogenic profile demonstrates that MVC-COV1901 induces high levels of neutralizing and binding antibodies against SARS-CoV-2. There is a dose-dependent response and a significant correlation between binding and neutralizing antibody activity. Antigen-specific T-cell responses, particularly a Th1-biased immune response characterized by high levels of interferon gamma and IL-2 cytokines, have also been observed. Coupled with this, MVC-COV1901 has favorable thermostability and better safety profiles when compared to other authorized vaccines from different platforms, which make it potentially a good candidate for vaccine supply chains in global markets.

Cost effectiveness of fractional doses of COVID-19 vaccine boosters in India.

BACKGROUND: Coronavirus disease 2019 (COVID-19) continues to be a major global public health crisis that exacts significant human and economic costs. Booster vaccination of individuals can improve waning immunity and reduce the impact of community epidemics. METHODS: Using an epidemiological model that incorporates population-level severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission and waning of vaccine-derived immunity, we identify the hypothetical potential of mass vaccination with fractionated vaccine doses specific to ChAdOx1 nCoV-19 (AZD1222 [Covishield]; AstraZeneca) as an optimal and cost-effective strategy in India's Omicron outbreak. FINDINGS: We find that the optimal strategy is 1/8 fractional dosing under mild (Re ∼ 1.2) and rapid (Re ∼ 5) transmission scenarios, leading to an estimated $6 (95% confidence interval [CI]: -13, 26) billion and $2 (95% CI: -26, 30) billion in health-related net monetary benefit over 200 days, respectively. Rapid and broad use of fractional dosing for boosters, together with delivery costs divided by fractionation, could substantially gain more net monetary benefit by $11 (95% CI: -10, 33) and $2 (95% CI: -23, 28) billion, respectively, under the mild and rapid transmission scenarios. CONCLUSIONS: Mass vaccination with fractional doses of COVID-19 vaccines to boost immunity in a vaccinated population could be a cost-effective strategy for mitigating the public health costs of resurgences caused by vaccine-evasive variants, and fractional dosing deserves further clinical and regulatory evaluation. FUNDING: Financial support was provided by the AIR@InnoHK Program from Innovation and Technology Commission of the Government of the Hong Kong Special Administrative Region.

Comprehensive assessment of SARS-CoV-2 antibodies against various antigenic epitopes after naive COVID-19 infection and vaccination (BNT162b2 or ChAdOx1 nCoV-19).

Comprehensive assessment of SARS-CoV-2 antibodies against antigenic epitopes and cross-neutralization on variants is essential to monitor after infection or vaccination. From 32 COVID-19 patients and 40 vaccinated individuals [20 Oxford-AstraZeneca (AZ) and 20 Pfizer-BioNTech (BNT)], 348 serial sera are collected until 40 days after infection and 3 months after homologous booster vaccination. Antibody levels were monitored using a multiplex-bead assay including variant spike antigens, Roche (S1/RBD total) and a surrogate virus neutralization test (GenScript). Anti-S/S1/RBD levels were higher than anti-S2/N levels from 2 weeks after infection and were higher in severe infection (P < 0.05). Vaccination showed highest antibody levels after 1-month booster and had consistently high levels in the order of anti-full S, anti-RBD, anti-S1 and anti-S2. Infection induced higher anti-S2/N levels than prime vaccination (P < 0.05). Three months after BNT/BNT vaccination, antibody levels against S1/RBD and 23 variant antigens were higher than post-infection or AZ groups (P < 0.05). Regarding intraindividual changes from post-prime to post-boost vaccination, boost induced a 1.1- to 3.9-fold increase on multiplex-bead assay, 22.8- to 24.2-fold on Roche assay and 22.8- to 24.2-fold on GenScript assay. Post-prime levels by multiplex-bead assay predicted post-boost levels, but Roche and GenScript results were not predictive in the AZ group. The kinetics of SARS-CoV-2 antibody levels vary depending on the antigenic epitopes, assay kit, disease severity or vaccine type. Assessing seroconversion using multiplex-bead assays may contribute to monitoring the disease course, adjusting vaccination strategies, and accelerating vaccination efficacy.

Efficacy of hydrogen peroxide wipes for decontamination of AZD1222 adenovirus COVID-19 vaccine strain on pharmaceutical industry materials.

This study aimed to evaluate the performance of accelerated hydrogen peroxide® wipes (HPW) for decontamination of the chimpanzee adenovirus AZD1222 vaccine strain used in the production of recombinant COVID-19 vaccine in a pharmaceutical industry. Two matrices were tested on stainless-steel (SS) and low-density-polyethylene (LDP) surfaces: formulated recombinant COVID-19 vaccine (FCV) and active pharmaceutical ingredient (API). The samples were spiked, dried and the initial inoculum, possible residue effect (RE) and titre reduction after disinfection with HPW were determined. No RE was observed. The disinfection procedure with HPW resulted in complete decontamination the of AZD1222 adenovirus strain in FCV (≥7·46 and ≥7·49 log10 infectious unit [IFU] ml-1 for SS and LDP carriers respectively) and API (≥8·79 and ≥8·78 log10 IFU ml-1 for SS and LDP carriers respectively). In conclusion, virucidal activity of HPW was satisfactory against the AZD1222 adenovirus strain and can be a good option for disinfection processes of SS and LPD surfaces in pharmaceutical industry facilities during recombinant COVID-19 vaccine production. This procedure is simple and can be also applied on safety unit cabins and sampling bags made of LDP as well.

Assessment of Immediate Allergic Reactions After Immunization With the Pfizer BNT162b2 Vaccine Using Intradermal Skin Testing With the COVID-19 Vaccines.

BACKGROUND: Allergic reactions to the coronavirus disease 2019 (COVID-19) vaccines have raised concerns, particularly as repeated doses are required. Skin tests with the vaccines excipient were found to be of low value, whereas the utility of skin tests with the whole vaccine is yet to be determined. OBJECTIVE: To evaluate a panel of skin tests and the outcomes of subsequent doses of immunization among subjects who suffered an immediate allergic reaction to the BioNTech (BNT162b2) COVID-19 vaccine. METHODS: Between March and December 2021, patients who experienced symptoms consistent with immediate allergic reactions to the BNT162b2 vaccine and were referred to the Sheba Medical Center underwent skin testing with polyethylene glyol (PEG)-containing medicines, Pfizer-BNT162b2, and Oxford-AstraZeneca vaccine (AZD1222). Further immunization was performed accordingly and under medical observation. RESULTS: A total of 51 patients underwent skin testing for suspected allergy to the COVID vaccines, of which 38 of 51 (74.5%) were nonreactive, 7 of 51(13.7%) had no skin sensitization but suffered a clinical reaction during skin testing (mainly cough), and 6 of 51 (11.7%) exhibited immediate skin sensitization. Both skin sensitization and cough during testing were related to a higher use of adrenaline following immunization (P = .08 and P = .024, respectively). Further immunization with the BNT162b2 vaccine was recommended unless sensitization or severe reaction to previous immunization was evident. The latter were referred to be tested/receive the alternative AZD1222 vaccine. Ten patients underwent skin testing with AZD1222: 2 of 10 (20%) demonstrated skin sensitization to both vaccines; thus, 8 of 10 were immunized with the AZD1222, of which 2 of 8 (25%) had allergic reactions. CONCLUSIONS: Immediate allergic reactions to COVID-19 vaccines are rare but can be severe and reoccur. Intradermal testing with the whole vaccine may discriminate sensitized subjects, detect cross-sensitization between vaccines, and enable estimation of patients at higher risk.

Evaluation of hydrogen peroxide efficacy against AZD1222 chimpanzee adenovirus strain in the recombinant COVID-19 vaccine for application in cleaning validation in a pharmaceutical manufacturing industry.

This study aimed to evaluate the performance of hydrogen peroxide vapour (HPV) to inactivate the chimpanzee adenovirus AZD1222 vaccine strain used in the production of recombinant COVID-19 vaccine for application in cleaning validation in pharmaceutical industries production areas. Two matrixes were tested: formulated recombinant COVID-19 vaccine (FCV) and active pharmaceutical ingredient (API). The samples were dried on stainless steel and exposed to HPV in an isolator. One biological indicator with population >106 Geobacillus stearothermophilus spores was used to validate the HPV decontamination cycle as standard. HPV exposure resulted in complete virus inactivation in FVC (≥5·03 log10 ) and API (≥6·40 log10 ), showing HPV efficacy for reducing chimpanzee adenovirus AZD1222 vaccine strain. However, the optimum concentration and contact time will vary depending on the type of application. Future decontamination studies scaling up the process to the recombinant COVID-19 vaccine manufacturing areas are necessary to evaluate if the HPV will have the same or better virucidal effectivity in each specific production area. In conclusion, HPV showed efficacy for reducing AZD1222 chimpanzee adenovirus strain and can be a good choice for pharmaceutical industries facilities disinfection during recombinant COVID-19 vaccine production.

Manufacturing a chimpanzee adenovirus-vectored SARS-CoV-2 vaccine to meet global needs.

Manufacturing has been the key factor limiting rollout of vaccination during the COVID-19 pandemic, requiring rapid development and large-scale implementation of novel manufacturing technologies. ChAdOx1 nCoV-19 (AZD1222, Vaxzevria) is an efficacious vaccine against SARS-CoV-2, based upon an adenovirus vector. We describe the development of a process for the production of this vaccine and others based upon the same platform, including novel features to facilitate very large-scale production. We discuss the process economics and the "distributed manufacturing" approach we have taken to provide the vaccine at globally-relevant scale and with international security of supply. Together, these approaches have enabled the largest viral vector manufacturing campaign to date, providing a substantial proportion of global COVID-19 vaccine supply at low cost.

Effect of Pfizer/BioNTech and Oxford/AstraZeneca vaccines against COVID-19 morbidity and mortality in real-world settings at countrywide vaccination campaign in Saudi Arabia.

OBJECTIVE: Vaccinations are highly essential to control infectious diseases and epidemics. Presently, the entire world faces a challenging crisis of "Severe Acute Respiratory Diseases Coronavirus 2 (SARS-CoV-2), also known as the COVID-19 pandemic". The impact of vaccines at national levels to reduce the SARS-CoV-2 cases and deaths are unclear, and people have concerns about the effectiveness of vaccines in real-world settings. This study's objective was to examine the effect of the "Pfizer/BioNTech and Oxford/AstraZeneca" vaccines to prevent SARS-CoV-2 cases and deaths in Saudi Arabia. MATERIALS AND METHODS: In this retrospective cohort study, we collected data on SARS-CoV-2 cases and deaths from the date of the first case of SARS-CoV-2 in Saudi Arabia March 2, 2020, to the date of launching the vaccination campaign on December 14, 2020; and from December 15, 2020, to September 8, 2021. We recorded the World Health Organization data and Ministry of Health of Saudi Arabia to evaluate the impact of the "Pfizer/BioNTech, (BNT162b2 mRNA) and Oxford/AstraZeneca (AZD1222)" vaccine against SARS-CoV-2 cases and deaths before and after the vaccination campaign in Saudi Arabia. RESULTS: Saudi Arabia launched the "Pfizer/BioNTech and Oxford/AstraZeneca" vaccination campaign against SARS-CoV-2 on December 14, 2020. In Saudi Arabia, before the vaccination campaign from March 2, 2020, to December 14, 2020, the mean daily SARS-CoV-2 cases were 1235.60, daily deaths were 22.70, that significantly reduced (p=0.0001) compared to the period after the vaccination campaign from December 15, 2020, to September 8, 2021, in which the daily cases fell to 692.08, and daily deaths fell to 9.48 (p=0.0001). CONCLUSIONS: In Saudi Arabia, Pfizer/BioNTech and Oxford/AstraZeneca vaccinations significantly reduced the number of SARS-CoV-2 cases and deaths after the vaccination compared to the period before the vaccination campaign at country levels. The study findings demonstrate that vaccination and adherence to nonpharmaceutical intervention can better control the COVID-19 pandemic.

Impact of COVID vaccination rollout on the use of computed tomography venography for the assessment of cerebral venous sinus thrombosis.

INTRODUCTION: Cerebral venous sinus thrombosis (CVST) is rare; however, it has been observed in patients with vaccine-induced immune thrombotic thrombocytopaenia syndrome (VITT) following the use of adenovirus vector vaccines against COVID-19. Adverse vaccine effects have been heavily addressed in mainstream media, likely contributing to vaccination anxiety. This study aimed to assess how the vaccine rollout and media coverage has influenced the use of computed tomography venography (CTV) in an acute care setting of a tertiary hospital. METHOD: Single-centre retrospective cohort study from 30 March 2021 to 13 June 2021. Direct comparison to same calendar dates in the preceding 3 years. RESULTS: In 2021, 57 patients received CTV with headache being the reason in 48 (84%) and 40 (70%) had received ChAdOx1 nCov-19 (AstraZeneca COVID-19 vaccination). Only 20 of these patients received CTV after platelets and D-Dimer had returned, and only three patients met existing guidelines for imaging. Zero cases were positive. The number of CTV studies was 5.2 times than in 2020 and 2.7 times the mean number for the 3 preceding years. CONCLUSION: The use of CTV in patients with headache has markedly increased at our centre since negatively biased vaccination influence of mainstream media. Headache is a common vaccine-related side effect and VITT is exceptionably rare. With the rates of vaccination increasing in the community, these results highlight the importance of strict adherence to established evidence-based guidelines. Otherwise, critical care capacity, and in particular imaging resources already under pressure will be strained further.

Effect of a hospital-wide campaign on COVID-19 vaccination uptake among healthcare workers in the context of raised concerns for life-threatening side effects.

BACKGROUND: All healthcare workers (HCWs) in Yongin Severance Hospital were allocated to receive the ChAdOx1 nCov-19 vaccine according to national policy. A report of thrombosis and thrombocytopenia syndrome (TTS) associated with ChAdOx1 nCoV-19 led to hesitancy about receiving the second dose among HCWs who had received the first dose. METHODS: From 7 to 14 May, 2021, we performed a survey to identify the factors associated with hesitancy about receiving the second vaccine dose among HCWs at the hospital who had received the first dose of the vaccine. Based on survey results, a hospital-wide campaign was implemented on 18 May 2021 to improve vaccine coverage. HCWs who completed the second dose completed a self-administered questionnaire to evaluate the effect of the campaign. FINDINGS: Of 1,171 HCWs who had received the first dose of the vaccine, 71.5% completed the online survey, of whom 3.7% refused to take the second dose and 22.3% showed hesitancy. Hesitancy to receive a second dose was significantly associated with age under 30 years and concerns about TTS, and was less common among those who trusted effectiveness and safety of the vaccine. Among HCWs who received the first dose, 96.2% completed vaccination with the second dose between 27 May and 4 June, 2021. Of those who answered the questionnaire asked about the timing of their decision to receive the second dose, 57.1% reported that they were motivated by the hospital-wide campaign. CONCLUSION: A tailored intervention strategy based on a survey can improve COVID-19 vaccination uptake among HCWs.

Anti-PF4 testing for vaccine-induced immune thrombocytopenia and thrombosis and heparin induced thrombocytopenia: Results from a UK National External Quality Assessment Scheme exercise April 2021.

BACKGROUND: Vaccine-induced immune thrombocytopenia and thrombosis (VITT) following the administration of the AstraZeneca (AZ) ChAdOx1 nCOV-19 vaccine has recently been reported. The associated clinical and laboratory features have included thrombosis at unusual sites, thrombocytopenia, and raised D-dimers with positivity for IgG anti-platelet factor 4 (PF4) antibodies. OBJECTIVES: A UK National External Quality Control Assessment Scheme external quality control exercise was carried out by distributing liquid and lyophilized samples from a subject with VITT, a pool of samples from subjects with classical heparin-induced thrombocytopenia (HIT), and a non-VITT/non-HIT case to 85 centers performing HIT testing. METHODS: Participating centers employed their locally validated testing methods for HIT assays. RESULTS: The lyophilized and liquid samples were found to be commutable for the ELISA assays used in the detection of anti-PF4 antibodies. The Aeskulisa, Stago, Hyphen, and LIFECODES anti-PF4 ELISA assays successfully detected the VITT antibody, whereas the Acustar HIT, Werfen LIA, and the Stago STIC assays did not. CONCLUSION: It is important that clinical and laboratory teams are aware of the limitations of some anti-PF4 assays when using them to aid diagnosis of VITT syndrome.

Economic evaluation for mass vaccination against COVID-19.

BACKGROUND: Vaccine is supposed to be the most effective means to prevent COVID-19 as it may not only save lives but also reduce productivity loss due to resuming pre-pandemic activities. Providing the results of economic evaluation for mass vaccination is of paramount importance for all stakeholders worldwide. METHODS: We developed a Markov decision tree for the economic evaluation of mass vaccination against COVID-19. The effectiveness of reducing outcomes after the administration of three COVID-19 vaccines (BNT162b2 (Pfizer-BioNTech), mRNA-1273 (Moderna), and AZD1222 (Oxford-AstraZeneca)) were modelled with empirical parameters obtained from literatures. The direct cost of vaccine and COVID-19 related medical cost, the indirect cost of productivity loss due to vaccine jabs and hospitalization, and the productivity loss were accumulated given different vaccination scenarios. We reported the incremental cost-utility ratio and benefit/cost (B/C) ratio of three vaccines compared to no vaccination with a probabilistic approach. RESULTS: Moderna and Pfizer vaccines won the greatest effectiveness among the three vaccines under consideration. After taking both direct and indirect costs into account, all of the three vaccines dominated no vaccination strategy. The results of B/C ratio show that one dollar invested in vaccine would have USD $13, USD $23, and USD $28 in return for Moderna, Pfizer, and AstraZeneca, respectively when health and education loss are considered. The corresponding figures taking value of the statistical life into account were USD $176, USD $300, and USD $443. CONCLUSION: Mass vaccination against COVID-19 with three current available vaccines is cost-saving for gaining more lives and less cost incurred.