Population-Based Serologic Survey of Vibrio cholerae Antibody Titers before Cholera Outbreak, Haiti, 2022.

A Vibrio cholerae O1 outbreak emerged in Haiti in October 2022 after years of cholera absence. In samples from a 2021 serosurvey, we found lower circulating antibodies against V. cholerae lipopolysaccharide in children <5 years of age and no vibriocidal antibodies, suggesting high susceptibility to cholera, especially among young children.

A population-based serological survey of Vibrio cholerae antibody titers in Ouest Department, Haiti in the year prior to the 2022 cholera outbreak.

After three years with no confirmed cholera cases in Haiti, an outbreak of Vibrio cholerae O1 emerged in October 2022. Levels of pre-existing antibodies provide an estimate of prior immunologic exposure, reveal potentially relevant immune responses, and set a baseline for future serosurveillance. We analyzed dried blood spots collected in 2021 from a population-weighted representative cross-sectional serosurvey in two communes in the Ouest Department of Haiti. We found lower levels of circulating IgG and IgA antibodies against V. cholerae lipopolysaccharide (LPS, IgG and IgA p<0.0001) in those below 5 years of age compared to those five years and older. Among a subset of patients with higher titers of antibodies, we were unable to detect any functional (vibriocidal) antibodies. In conclusion, the lack of detectable functional antibodies, and age-discordant levels of V. cholerae LPS IgG, suggest that populations in Haiti may be highly susceptible to cholera disease, especially among young children.

What Happens to the Immune System after Vaccination or Recovery from COVID-19?

Due to its leading role in fighting infections, the human immune system has been the focus of many studies in the context of Coronavirus disease 2019 (COVID-19). In a worldwide effort, the scientific community has transitioned from reporting about the effects of the novel coronavirus on the human body in the early days of the pandemic to exploring the body's many immunopathological and immunoprotecting properties that have improved disease treatment and enabled the development of vaccines. The aim of this review is to explain what happens to the immune system after recovery from COVID-19 and/or vaccination against SARS-CoV-2, the virus that causes the disease. We detail the way in which the immune system responds to a SARS-CoV-2 infection, including innate and adaptive measures. Then, we describe the role of vaccination, the main types of COVID-19 vaccines and how they protect us. Further, we explain the reason why immunity after COVID-19 infection plus a vaccination appears to induce a stronger response compared with virus exposure alone. Additionally, this review reports some correlates of protection from SARS-CoV-2 infection. In conclusion, we reinforce that vaccination is safe and important in achieving herd immunity.

Relevance of antibodies against the Chicken Anaemia Virus.

Chicken Infectious Anaemia (CIA) Virus (CAV) inhibits the function of multiple immune compartments. Mortality due to clinical infection is controlled in broilers by passive immunization derived from vaccinated breeders. Therefore, serological tests are often used in chicks to determine maternally-derived antibodies (MDA). We used a vaccine overdose-induced model of CIA. The model replicated the most common features of the disease. This model was used to determine the role of MDA in the protection of chicks. Hatchlings were tested for anti-CAV titers by ELISA and were sorted into groups based on antibody levels. SPF chicks were used as a no-antibody control. Lower specific antibody levels seemed to facilitate viral entry into the thymus, but viral levels, CD4+ and CD8+ counts, thymus architecture, and haematocrit were preserved by MDA, regardless of its levels. Levels of MDA are not correlated with protection from CIA, but are important for the progression CAV infection.

Interferon-gamma production by mononuclear cells in Bacille Calmette-Guérin-revaccinated healthy volunteers predicted long-term antimycobacterial responses in a randomized controlled trial.

The Bacille Calmette-Guérin (BCG) vaccine is the only vaccine currently available for tuberculosis, and it demonstrates variable efficacy against the disease. The assessment of new vaccine strategies is hindered by the small annual probability that an infected individual will develop tuberculosis, and the lack of simple and reliable surrogate markers of protection. The frequency of cytokine-producing T cells as well as the production of IFN-γ have been disputed as surrogate markers of protection. We evaluated the evolution of these immune parameters in a population from a high burden city where BCG revaccination has been shown to result in mild protection. We found that individuals whose in vitro IFN-γ responses to mycobacterial antigens had increased by more than 3.3-fold were more likely to maintain higher responses after 1 year and to show increased expansion of IFN-γ-producing T lymphocytes than those with lower or null increase of IFN-γ.