A short history of vaccination

Is vaccine confidence an unexpected victim of the COVID-19 pandemic?

Vaccines are among the safest and most effective primary prevention measures. Thanks to the synergistic global efforts of research institutions, pharmaceutical companies and national health services, COVID-19 vaccination campaigns were successfully rolled out less than a year after the start of the pandemic. While the unprecedented speed of development and approval of COVID-19 vaccines has been applauded as a public health success story, it also spurred considerable controversy and hesitancy even amongst individuals that did not previously hold anti-vaccination stances. This study aimed to compare pre- and post-pandemic vaccine confidence trends in different demographic groups by analysing the outcomes of two online surveys run respectively in November 2019 and January 2022 involving a total of 1009 participants. Non-parametric tests highlighted a statistically significant decline in vaccine confidence in the 2022 cohort compared to the 2019 cohort, with median Vaccine Confidence Score dropping from 22 to 20 and 23.8% of participants reporting that their confidence in vaccines had declined since the onset of the pandemic. While the majority of internal trends were comparable between the two surveys with regards to gender, graduate status and religious belief, vaccine confidence patterns showed considerable alterations with regards to age and ethnicity. Middle-aged participants were considerably more hesitant than younger groups in the 2019 cohort, however this was not the case in the 2022 survey. In both surveys White participants showed significantly higher vaccine confidence than those from Black backgrounds; in the 2022 cohort, unlike the pre-pandemic group, Asian participants showed significantly lower confidence than White ones. This study suggests that paradoxically, despite the success of COVID-19 vaccination campaigns, vaccine confidence has significantly declined since the onset of the pandemic; the comparison of a pre- and post-pandemic cohort sheds light on the differential effect that the pandemic had on vaccine confidence in different demographic groups.

COVID-19 vaccine hesitancy in Sana'a, Yemen

Background and Aim: The development of a coronavirus disease 2019 (COVID-19) vaccine is ongoing. This study aimed to prepare for public acceptance of the vaccine. There is a need to identify the current acceptance and potential barriers to receiving a COVID-19 vaccine in Yemen. Understanding the hesitancy and acceptance of a COVID-19 vaccine are crucial to develop local evidence-based interventions. Materials and Methods: Twenty students were interviewed in this study. An interview guide was developed and it addressed the willingness to accept a future COVID-19 vaccine. In-depth interviews were conducted, transcribed, and manually analyzed. Results: The majority of participants agreed that they would take a COVID-19 vaccine for several reasons, including protection for themselves, their families, and others and to stop the spread of COVID-19, for which the vaccine is important, as in other routine vaccinations. However, some participants shared that they would not take the COVID-19 vaccine due to the following reasons: Concerns regarding the safety of the vaccine; feeling fit and healthy, and thus considering themselves to have strong immunity; feeling that the vaccine was manufactured in a rushed manner and thus it would require approval by the World Health Organization; being previously infected with COVID-19 and considering themselves protected, and placing their trust in God and believing no vaccine was needed. Conclusion: The willingness to receive a future COVID-19 vaccine was high among medical students. However, some students hesitated to take the vaccine. Therefore, mass media interventions are required to maximize vaccine uptake.

Impact of educational intervention on the best immunization practices among practicing health care professionals in a south Indian city

Background and Aims

Maintaining the quality and safety of immunization is as important as the efficacy of vaccines in vaccine-preventable diseases (VPD) programs. The aim of this study was to determine the problems associated with different stages of vaccine use and to assess the outcome of an educational intervention on safety and quality use of vaccines among health care providers.

Methods

A pilot prospective interventional study was conducted over a period of 2 years at 271 sites in Mysuru, India. The study population was health care professionals (HCPs) involved in immunization and a sample of parents (one per site). A validated questionnaire was used as a study tool. An educational intervention on best immunization practice was conducted for the enrolled HCPs and the impact of the educational intervention was assessed using the study tool after 3 weeks.

Results

The total number of the study population was 594 (323 HCPs and 271 parents). Of these, 41.49% were working at community health care facility and 33.13% were enrolled from primary care centers. There were statistically significant improvements in post interventional assessment of all stages of the immunization process including storage (p -0.001), transportation (p -0.001), administration (p 0.001), monitoring and reporting of adverse events following immunization (AEFIs) (p -0.001), knowledge of AEFIs (p 0.001), and HCP-parent communication (p 0.001). AEFI reporting improved by 30% in the post education phase.

Conclusion

Continuous education and motivation can result in positive behavioral changes on best immunization practices amongst HCPs involved in immunization, which may help to improve and maintain the safety and quality use of vaccines in immunization centers irrespective of the type of facility.

Why the evolution of vaccine resistance is less of a concern than the evolution of drug resistance

Vaccines and antimicrobial drugs both impose strong selection for resistance. Yet only drug resistance is a major challenge for 21st century medicine. Why is drug resistance ubiquitous and not vaccine resistance? Part of the answer is that vaccine resistance is far less likely to evolve than drug resistance. But what happens when vaccine resistance does evolve? We review six putative cases. We find that in contrast to drug resistance, vaccine resistance is harder to detect and harder to confirm and that the mechanistic basis is less well understood. Nevertheless, in the cases we examined, the pronounced health benefits associated with vaccination have largely been sustained. Thus, we contend that vaccine resistance is less of a concern than drug resistance because it is less likely to evolve and when it does, it is less harmful to human and animal health and well-being. Studies of pathogen strains that evolve the capacity to replicate and transmit from vaccinated hosts will enhance our ability to develop next-generation vaccines that minimize the risk of harmful pathogen evolution.

MHC Class II Binding Prediction-A Little Help from a Friend

Vaccines are the greatest single instrument of prophylaxis against infectious diseases, with immeasurable benefits to human wellbeing. The accurate and reliable prediction of peptide-MHC binding is fundamental to the robust identification of T-cell epitopes and thus the successful design of peptide- and protein-based vaccines. The prediction of MHC class II peptide binding has hitherto proved recalcitrant and refractory. Here we illustrate the utility of existing computational tools for in silico prediction of peptides binding to class II MHCs. Most of the methods, tested in the present study, detect more than the half of the true binders in the top 5% of all possible nonamers generated from one protein. This number increases in the top 10% and 15% and then does not change significantly. For the top 15% the identified binders approach 86%. In terms of lab work this means 85% less expenditure on materials, labour and time. We show that while existing caveats are well founded, nonetheless use of computational models of class II binding can still offer viable help to the work of the immunologist and vaccinologist.

Vaccination of HIV-infected adults

Vaccination has been shown to be one of the most powerful tools to decrease morbidity and mortality caused by an array of infectious diseases. The risk and complications of some vaccine-preventable diseases is higher in HIV-infected individuals, underscoring the importance of vaccination in these patients. However, the immune response upon vaccination is generally impaired and shorter lasting in HIV-infected individuals, especially in those with low CD4+ T-lymphocyte counts and detectable HIV RNA, as compared with healthy controls. Even in patients responding to antiretroviral treatment, an impaired immune response may persist despite normalization of the CD4+-cell count. Caution with live-attenuated vaccines is warranted in HIV-infected individuals with low CD4 T-lymphocyte counts. Decisions regarding administering a live-attenuated vaccine should be made after weighing the risks and benefits on an individual basis. In this article the immunology of vaccination in HIV-infected individuals, as well as the most relevant caveats of vaccination in this patient group, are reviewed in addition to the currently available information concerning the influenza A/H1N1 2009 monovalent vaccine.

[Specific aspects of vaccine manufacturing]

La production de vaccin à l’échelle industrielle connaît son essor au cours de la seconde moitié du xx^e siècle. Le vaccin est un médicament qui a la particularité de s’adresser à des sujets bien portants. Les principes actifs qui le composent sont issus d’organismes vivants et se différencient de ceux de la chimie classique par leurs structures moléculaires souvent complexes et parfois mal identifiées. Les propriétés de la préparation vaccinale dépendent étroitement du procédé de production mis en œuvre et il est commun d’admettre que « le procédé fait le produit ». La fabrication s’effectue en zones confinées, due aux caractères pathogènes de la plupart des microorganismes impliqués. Les matières premières sont soumises à des contrôles rigoureux afin de garantir l’intégrité des produits vis-à-vis de contaminants viraux ou d’agents transmissibles non conventionnels comme le prion. L’industrie du vaccin est caractérisée par la longueur des cycles de production. La complexité des produits implique celle des contrôles qualité dont l’activité représente en moyenne 75 % de la durée du cycle total de fabrication. En tant qu’élément majeur de santé publique, le monde du vaccin est soumis à des à-coups de production en fonction de la demande extérieure, en particulier dans les contextes d’épidémie ou de menaces de bioterrorisme. En parallèle, l’industrie du vaccin doit intégrer les exigences toujours plus pressantes des autorités de santé. Le développement spectaculaire des départements assurance qualité et contrôle qualité, ces quinze dernières années, témoignent de cette évolution.