Objetivos: Estimar la prevalencia y los factores asociados a la intención de vacunación (IDV) contra la COVID-19 en el Perú. Materiales y métodos: Estudio transversal analítico utilizando una encuesta realizada por la Universidad de Maryland, EUA, en Facebook. La variable dependiente fue la IDV. Se calcularon razones de prevalencia (RP) crudas y ajustadas, con sus intervalos de confianza al 95% (IC95%), mediante modelos lineales generalizados de la familia Poisson para evaluar la asociación de variables sociodemográficas, el cumplimiento de estrategias comunitarias de mitigación, los síntomas de la COVID-19, la salud mental y la aceptación de la vacunación ante la recomendación (AVR) por diversos actores y autoridades sanitarias. Resultados: Se analizaron los datos de 17 162 adultos. La prevalencia general de la IDV fue del 74,9%. Se asociaron a una menor prevalencia de la IDV ser de sexo femenino (RP = 0,95; IC95%: 0,94-0,97), vivir en un pueblo (RP = 0,95; IC95%: 0,91-0,99) o en una aldea u otra área rural (RP = 0,90; IC95%: 0,86-0,93) y la AVR de políticos (RP = 0,89; IC95%: 0,87-0,92). Contrariamente, tener síntomas de COVID-19 (RP = 1,06; IC95%: 1,03-1,09), inseguridad económica (RP = 1,04; IC95%: 1,01-1,06), miedo a enfermar o que un familiar enferme de COVID-19 (RP = 1,49; IC95%: 1,36-1,64) y la AVR de familiares y amigos (RP = 1,10; IC95%: 1,08-1,12), trabajadores de la salud (RP = 1,29; IC95%: 1,26- 1,32), la Organización Mundial de la Salud (RP = 1,34; IC95%: 1,29-1,40) y funcionarios del gobierno (RP = 1,18; IC95%: 1,15-1,22) se asociaron con mayor prevalencia de IDV. Conclusiones: Tres cuartas partes de los encuestados manifiestan IDV. Existen factores potencialmente modificables que podrían mejorar la aceptación de la vacuna. / Objectives: To estimate the prevalence and factors associated with COVID-19 vaccination intention (VI) in Peru. Materials and methods: Analytical cross-sectional study using the survey conducted by the University of Maryland, USA, on Facebook. The dependent variable is VI. Crude and adjusted prevalence ratios (PR) were calculated, with their 95% confidence intervals (95%CI) using generalized linear models of the Poisson family, to evaluate the association of sociodemographic variables, com- pliance with community mitigation strategies, symptoms of COVID-19, mental health and acceptance of vaccination before the recommendation (AVR) by various actors and health authorities, with the ITV. Results: Data from 17,162 adults were analyzed. The overall prevalence of VI was 74.9%. A lower prevalence of VI was associated with the female sex (PR=0.95; 95%CI:0.94-0.97), living in a town (PR=0.95; 95%CI:0.91-0.99) or village or other rural area (PR=0.90; 95%CI:0.86-0.93) and the AVR of politicians (PR=0.89; 95%CI:0.87-0.92). Conversely, having COVID-19 symptoms (PR=1.06; 95%CI:1.03-1.09), economic insecurity (PR=1.04; 95%CI:1.01-1.06), fears of becoming seriously ill or that a family member becomes seriously ill from COVID-19 (PR=1.49; 95%CI:1.36-1.64) and the AVR of family and friends (PR=1.10; 95%CI: 1.08-1.12), healthca- re workers (PR=1.29; 95%CI: 1.26-1.32), World Health Organization (PR=1.34; 95%CI: 1.29-1.40) and government officials (PR=1.18; 95%CI: 1.15-1.22) was associated with a higher prevalence of VI. Conclusio of the respondents had VI. There are potentially modifiable factors that could improve vaccine acceptance.

INTRODUCTION: Coronavirus Disease (COVID-19) vaccine acceptance, and hesitancy amongst Health Care Workers (HCWs) on the African continent have been examined through observational studies. However, there are currently no comprehensive reviews among these cadre of population in Africa. Hence, we aimed to review the acceptance rate and possible reasons for COVID-19 vaccine non-acceptance/hesitancy amongst HCWs in Africa. METHODS: We searched Medline/PubMed, Google Scholar, and Africa Journal Online from January, 2020 to September, 2021. The Newcastle-Ottawa Quality Assessment tool adapted for cross-sectional studies was used to assess the quality of the retrieved studies. DerSimonian and Laird random-effects model was used to pool the COVID-19 vaccine acceptance rate. Sub-group and sensitivity analyses were performed. Reasons for COVID-19 vaccine hesitancy were also systematically analyzed. RESULTS: Twenty-one (21) studies were found to be eligible for review out of the 513 initial records. The estimated pooled COVID-19 vaccine acceptance rate was 46% [95% CI: 37%-54%]. The pooled estimated COVID-19 vaccine acceptance rate was 37% [95% CI: 27%-47%] in North Africa, 28% [95% CI: 20%-36%] in Central Africa, 48% [CI: 38%-58%] in West Africa, 49% [95% CI: 30%-69%] in East Africa, and 90% [CI: 85%-96%] in Southern Africa. The estimated pooled vaccine acceptance was 48% [95% CI:38%-57%] for healthcare workers, and 34% [95% CI:29%-39%] for the healthcare students. Major drivers and reasons were the side effects of the vaccine, vaccine's safety, efficacy and effectiveness, short duration of the clinical trials, COVID-19 infections, limited information, and social trust. CONCLUSION: The data revealed generally low acceptance of the vaccine amongst HCWs across Africa. The side effects of the vaccine, vaccine's safety, efficacy and effectiveness, short duration of the clinical trials, COVID-19 infections, limited information, and social trust were the major reasons for COVID-19 hesitancy in Africa. The misconceptions and barriers to COVID-19 vaccine acceptance amongst HCWs must be addressed as soon as possible in the continent to boost COVID-19 vaccination rates in Africa.

Background: Guidelines recommend that patients with haemophilia should preferably receive vaccination subcutaneously. COVID-19 and other vaccines, however, are only licenced for intramuscular application. Aims: To assess the safety of intramuscular COVID-19 vaccination in patients living with haemophilia. Methods: Part A of this prospective observational study enrolled consecutive patients with haemophilia A (HA) and B (HB) of all ages and severities and assessed injection site bleeding and other complications within 30 days of vaccination. Part B enrolled patients providing informed consent for detailed data collection including medication and prophylaxis around the time of vaccination. Logistic regression was performed to assess potential risk factors for bleeding. Results: Four hundred and sixty-one patients were enrolled into part A. The primary endpoint injection site bleeding occurred in seven patients (1.5%, 95% confidence interval .7–3.1%). Comprehensive analysis of 214 patients (404 vaccinations, part B) revealed that 97% of patients with severe haemophilia had prophylaxis before vaccination, either as part of their routine prophylaxis or using additional doses. 56% and 30% of patients with moderate and mild haemophilia, respectively, received prophylaxis before vaccination. Among the seven bleeds recorded, three occurred when intramuscular vaccination was done without prophylaxis (odds ratio 12). Conclusions: This is the first prospective study reporting on the safety of intramuscular vaccination in haemophilia. The rate of injection site bleeding was low in mild haemophilia, and in moderate and severe haemophilia if patients received factor prophylaxis.

To increase medicine safety, researchers use adverse event reports to assess causal relationships between drugs and suspected adverse reactions. VigiBase, the world's largest database of such reports, collects data from numerous sources, introducing the risk of several records referring to the same case. These duplicates negatively affect the quality of data and its analysis. Thus, efforts should be made to detect and clean them automatically.  Today, VigiBase holds more than 3.8 million COVID-19 vaccine adverse event reports, making deduplication a challenging problem for existing solutions employed in VigiBase. This thesis project explores methods for this task, explicitly focusing on records with a COVID-19 vaccine. We implement Jaccard similarity, TF-IDF, and BERT to leverage the abundance of information contained in the free-text narratives of the reports. Mean-pooling is applied to create sentence embeddings from word embeddings produced by a pre-trained SapBERT model fine-tuned to maximise the cosine similarity between narratives of duplicate reports. Narrative similarity is quantified by the cosine similarity between sentence embeddings.  We apply a Gradient Boosted Decision Tree (GBDT) model for classifying report pairs as duplicates or non-duplicates. For a more calibrated model, logistic regression fine-tunes the leaf values of the GBDT. In addition, the model successfully implements a ruleset to find reports whose narratives mention a unique identifier of its duplicate. The best performing model achieves 73.3% recall and zero false positives on a controlled testing dataset for an F1-score of 84.6%, vastly outperforming VigiBase’s previously implemented model's F1-score of 60.1%. Further, when manually annotated by three reviewers, it reached an average 87% precision when fully deduplicating 11756 reports amongst records relating to hearing disorders.

This study compared the immunogenicity of inactivated SARS-CoV-2 vaccines between people living with HIV (PLWH) and HIV-negative individuals. We recruited 120 PLWH and 53 HIV-negative individuals aged 18-59 years who had received an inactivated SARS-CoV-2 vaccine in two Chinese cities between April and June 2021. Blood samples were tested for immunogenicity of the inactivated SARS-CoV-2 vaccines. The prevalence and severity of adverse events associated with SARS-CoV-2 vaccines were similar between PLWH and HIV-negative individuals. The seropositivity of neutralizing activity against authentic SARS-CoV-2, of the total amount of antibody (total antibody) and of S-IgG were 71.3%, 81.9%, and 92.6%, respectively, among fully vaccinated PLWH. Among all participants, PLWH had lower neutralizing activity, total antibody, S-IgG, and T-cell-specific immune response levels, compared to HIV-negative individuals, after controlling for types of vaccine, time interval between first and second dose, time after receiving the second dose, and sociodemographic factors. PLWH with a longer interval since HIV diagnosis, who received their second dose 15-28 days prior to study commencement, and who had an interval of ≥21 days between first and second dose had higher neutralizing activity levels. The immunogenicity of the inactivated SARS-CoV-2 vaccines was lower among PLWH as compared to HIV-negative individuals. Vaccination guideline specific for PLWH should be developed.