Long-term systemic and mucosal SARS-CoV-2 IgA response and its association with persistent smell and taste disorders.

Introduction: Current approved COVID-19 vaccines, notably mRNA and adenoviral vectored technologies, still fail to fully protect against infection and transmission of various SARS-CoV-2 variants. The mucosal immunity at the upper respiratory tract represents the first line of defense against respiratory viruses such as SARS-CoV-2 and is thus critical to develop vaccine blocking human-to-human transmission. Methods: We measured systemic and mucosal Immunoglobulin A (IgA) response in serum and saliva from 133 healthcare workers from Percy teaching military hospital following a mild infection (SARS-CoV-2 Wuhan strain, n=58) or not infected (n=75), and after SARS-CoV-2 vaccination (Vaxzevria®/Astrazeneca and/or Comirnaty®/Pfizer). Results: While serum anti-SARS-CoV-2 Spike IgA response lasted up to 16 months post-infection, IgA response in saliva had mostly fallen to baseline level at 6 months post-infection. Vaccination could reactivate the mucosal response generated by prior infection, but failed to induce a significant mucosal IgA response by itself. Early post-COVID-19 serum anti-Spike-NTD IgA titer correlated with seroneutralization titers. Interestingly, its saliva counterpart positively correlated with persistent smell and taste disorders more than one year after mild COVID-19. Discussion: As breakthrough infections have been correlated with IgA levels, other vaccine platforms inducing a better mucosal immunity are needed to control COVID-19 infection in the future. Our results encourage further studies to explore the prognosis potential of anti-Spike-NTD IgA in saliva at predicting persistent smell and taste disorders.

A live measles-vectored COVID-19 vaccine induces strong immunity and protection from SARS-CoV-2 challenge in mice and hamsters.

Several COVID-19 vaccines have now been deployed to tackle the SARS-CoV-2 pandemic, most of them based on messenger RNA or adenovirus vectors.The duration of protection afforded by these vaccines is unknown, as well as their capacity to protect from emerging new variants. To provide sufficient coverage for the world population, additional strategies need to be tested. The live pediatric measles vaccine (MV) is an attractive approach, given its extensive safety and efficacy history, along with its established large-scale manufacturing capacity. We develop an MV-based SARS-CoV-2 vaccine expressing the prefusion-stabilized, membrane-anchored full-length S antigen, which proves to be efficient at eliciting strong Th1-dominant T-cell responses and high neutralizing antibody titers. In both mouse and golden Syrian hamster models, these responses protect the animals from intranasal infectious challenge. Additionally, the elicited antibodies efficiently neutralize in vitro the three currently circulating variants of SARS-CoV-2.

Differential serological and neutralizing antibody dynamics after an infection by a single SARS-CoV-2 strain.

BACKGROUND: We report here the case of two coworkers infected by the same SARS-CoV-2 strain, presenting two different immunological outcomes. CASE: One patient presented a strong IgG anti-receptor-binding domain immune response correlated with a low and rapidly decreasing titer of neutralizing antibodies. The other patient had a similar strong IgG anti-receptor-binding domain immune response but high neutralizing antibody titers. DISCUSSION AND CONCLUSION: Thus, host individual factors may be the main drivers of the immune response varying with age and clinical severity.

[COVID-19 and vaccination: a global disruption]. / COVID-19 et vaccination : une dérégulation globale.

Coronavirus disease (COVID)-19 is an emerging pandemic infection whose significant ability to spread in a naïve population is well established. The first response of states to the COVID-19 outbreak was to impose lock-down and social barrier measures, such as wearing a surgical mask or social distancing. One of the consequences of this pandemic in terms of public health was the suspension or slowdown of infant vaccination campaigns, in almost all countries. The indirect effects of COVID-19 may therefore weigh on mortality from measles and polio in developing countries. In this pandemic chaos, the only hope lies in the rapid development of an effective vaccine against severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). However, acceptance of this vaccine has not yet been won, as beyond the many unknowns that will inevitably weigh around such rapid development, skepticism among vaccine hesitants is growing.

TITLE: COVID-19 et vaccination : une dérégulation globale. ABSTRACT: La COVID-19 est une infection pandémique émergente dont l'importante capacité à se propager dans une population dénuée d'immunité n'est plus à prouver. La première réponse des États à la flambée de COVID-19 fut d'imposer un confinement et des mesures barrières, telles que le port du masque et la distanciation sociale. Une des répercussions de cette pandémie, en matière de santé publique, fut la suspension ou le ralentissement brusque des campagnes de vaccination des nourrissons, un peu partout dans le monde. Un des effets indirects de la COVID-19 est donc le risque de peser sur la mortalité mondiale, principalement via une recrudescence de la rougeole et de la poliomyélite, principalement dans les pays en voie de développement. Dans ce chaos potentiel, le seul espoir réside dans le développement rapide d'un vaccin efficace contre le SARS-CoV-2 (severe acute respiratory syndrome-coronavirus-2). Cependant, l'acceptation de ce vaccin par la population n'est pas évidente, car outre les nombreuses inconnues qui vont peser inévitablement dans le cas d'un développement très rapide du vaccin, le scepticisme des hésitants vaccinaux va à nouveau se développer.