Hepatitis B vaccination and central demyelination - History, description and observed/expected analyses of 624 cases reported to the French pharmacovigilance over a 20-year period

Immunogenicity and safety of vaccines in multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

Seroconversion rate of vaccines varies and requires further elucidation in patients with multiple sclerosis (MS) under treatment with disease-modifying therapies (DMTs). We aimed to investigate this in a systematic review and meta-analysis.

METHODS

MEDLINE(PubMed) and Cochrane databases were searched based on a pre-specified protocol (PROSPERO: CRD42020202018). Studies reporting on patients with MS, diagnosed with McDonald criteria getting vaccinated with any type of vaccine were included in the analysis. The primary endpoint was the incidence of patients being seropositive and experience adverse events after vaccination. Outcomes were expressed as proportions with respective 95% confidence interval (CI). Two reviewers independently screened and reviewed existing literature and assessed study quality with the Methodological index for non-randomized studies.

RESULTS

Of 295 articles, 45 studies were analyzed. Seroconversion after COVID-19 vaccines was 76% (95% CI, 70-80; I2 = 95%; 20 studies including 5601 patients. Protection was lower in patients treated with anti-CD20 antibodies and sphingosine-1-phosphate receptor (S1PR) modulators compared to untreated patients or treatment with other DMTs. Relapse occurred in 2% (95% CI, 1-3; I2 = 86%; 16 studies including 7235 patients). Seroconversion after seasonal influenza vaccines was 82% (95% CI, 65-91; I2 = 90%; 6 studies including 490 patients). Relapse rate was similar to this after COVID-19 vaccination.

CONCLUSION

The majority of MS patients vaccinated for COVID-19 or seasonal influenza mount an adequate immune response without safety concerns. Data on other vaccines are limited.

Interpretation of vaccine associated neurological adverse events: a methodological and historical review

As a result of significant recent scientific investment, the range of vaccines available for COVID-19 prevention continues to expand and uptake is increasing globally. Although initial trial safety data have been generally reassuring, a number of adverse events, including vaccine induced thrombosis and thrombocytopenia (VITT), have come to light which have the potential to undermine the success of the vaccination program. However, it can be difficult to interpret available data and put these into context and to communicate this effectively. In this review, we discuss contemporary methodologies employed to investigate possible associations between vaccination and adverse neurological outcomes and why determining causality can be challenging. We demonstrate these issues by discussing relevant historical exemplars and explore the relevance for the current pandemic and vaccination program. We also discuss challenges in understanding and communicating such risks to clinicians and the general population within the context of the 'infodemic' facilitated by the Internet and other media.

Attitudes towards the COVID-19 Vaccine and Willingness to Get Vaccinated among Healthcare Workers in French Guiana: The Influence of Geographical Origin

Background: In the context of the global COVID-19 pandemic and the expansion of the more transmissible 20J/501Y.V3 (Gamma) variant of concern (VOC), mRNA vaccines have been made available in French Guiana, an overseas French territory in South America, from mid-January 2021. This study aimed to estimate the willingness to be vaccinated and the socio-demographic and motivational correlates among Health Care Workers (HCWs) in French Guiana. Methods: A cross-sectional survey was conducted from January 22 to March 26, 2021 among a sample of HCWs in French Guiana. They were asked about their willingness to get vaccinated against COVID-19 and vaccine hesitancy, vaccine uptake and vaccines attitudes. Factors associated with willingness to get vaccinated have been analyzed with ordinal logistic regression, using Stata software. Results: A total of 579 HCWs were interviewed, including 220 physicians and 200 nurses most often working in hospital (54%) or in the liberal sector (22%). Overall, 65.6% of respondents reported that they were willing or had already been vaccinated against COVID-19, while 24.3% of respondents reported that they did not want to get vaccinated against COVID-19 and 11.2% were unsure. HCWs were more willing to get vaccine if they were older, were worried about COVID-19 and were confident in the management of epidemic. Conversely, participants were less likely to have been vaccinated or willing to if they were nurses or of another non-medical profession, born in French Guiana, feared adverse effects, or if they did not trust pharmaceutical companies and management of the epidemic by authorities. Conclusion: Negative attitudes towards vaccines are a major public health concern among HCWs in French Guiana when considering the current active epidemic with Gamma VOC. General vaccine hesitancy and concerns about future side effects in particular represent important barriers. Low confidence in government and science are significant in COVID-19 vaccine refusal among non-medical staffs. Public health messaging with information on vaccine safety should be tailored to address these concerns. The specific challenges of HCWs from French Guiana must be taken into account.

Do Vaccines Have a Role as a Cause of Autoimmune Neurological Syndromes?

Vaccines are the most important preventive measure against infectious diseases presently available. Although they have led to the eradication or the elimination of some infectious diseases, concerns about safety are among the main reasons for vaccine hesitancy. In some cases, the biological plausibility of a given damage in association with the temporal association between vaccine administration and disease development makes it difficult to define causality and can justify hesitancy. Only well-conducted epidemiological studies with adequate evaluation of results can clarify whether a true association between vaccines and adverse event development truly exists. Autoimmune neurological syndromes that follow vaccine use are among these. In this narrative review, the potential association between vaccines and the development of these syndromes are discussed. Literature analysis showed that most of the associations between vaccines and nervous system autoimmune syndromes that have been reported as severe adverse events following immunization are no longer evidenced when well-conducted epidemiological studies are carried out. Although the rarity of autoimmune diseases makes it difficult to strictly exclude that, albeit exceptionally, some vaccines may induce an autoimmune neurological disease, no definitive demonstration of a potential role of vaccines in causing autoimmune neurological syndromes is presently available. Consequently, the fear of neurological autoimmune disease cannot limit the use of the most important preventive measure presently available against infectious diseases.