diphtheria+tetanus+bordetella pertussis vaccine (DPT Kovax)

Pre-existing antibodies predict protection while mucosal inflammation correlates with symptomatic Bordetella pertussis infection.

Willemsen Lisa L, Ren Ziyuan Z, Shinde Pramod P, Thrupp Nicola N et al.

Despite decades of widespread vaccination, whooping cough caused by Bordetella pertussis (Bp) continues to circulate globally. To define correlates of protection and mechanisms underlying symptom development, we characterized systemic and mucosal immune responses in a controlled human infection model of Bp ( NCT05136599 ). Healthy vaccinated adults were intranasally challenged with escalating Bp doses and classified as symptomatic, asymptomatic, or non-infected. Longitudinal sampling of blood and nasal mucosa allowed mapping of antibody titers, immune cell subset frequencies, cytokine concentrations, gene expression, and T cell activation and polarization. Non-infected participants exhibited significantly higher pre-challenge serum antigen-specific IgG titers. Post-challenge, only symptomatic participants developed robust antigen-specific IgG responses. Notably, infection-induced IgG responses displayed slower kinetics and a lower overall magnitude compared to the rapid day 7 peak observed following tetanus, diphtheria, and acellular pertussis (Tdap) booster vaccination. Furthermore, symptomatic infection was driven by pronounced nasal inflammation characterized by increased HLA-DRLJ myeloid cells and upregulated mucosal NF-κB signaling on day 7. Systemic immune responses were comparatively modest post-challenge: plasma cytokine concentrations decreased independently of clinical outcome, peripheral blood mononuclear cell transcriptomes and antigen-specific T cell activation and polarization remained largely unchanged. These findings identify pre-existing serum antibodies as potential correlates of protection from Bp infection and suggest that symptom development is associated with localized mucosal inflammation dominated by a myeloid cell response. The predominance of nasal over systemic immune activation highlights the importance of mucosal immunity in controlling Bp and provides critical insights to guide the design of next-generation vaccines aimed at preventing both disease and transmission.

Interpreting correlates of protection against Bordetella pertussis colonisation in the context of early-life immune imprinting.

Zhang Jingfen J, Cheng Na N, Xiang Tianxin T

Exposure to P. falciparum and common cold viruses shape vaccine responses in early life.

Bach Florian F, Sigal George G, Wohlstadter Jacob J, Brown Rayven R et al.

Vaccine immunogenicity is consistently lower in low-income countries than in high-income settings, yet the factors driving this disparity remain incompletely understood. Using multiplexed electrochemiluminescence serology, we measured IgG and IgA responses to Expanded Program on Immunization (EPI) vaccines and common childhood viral infections in 89 Ugandan infants. We integrated detailed parasitological surveillance and maternal clinical data to examine how P. falciparum infection history, concurrent parasitemia, maternal gravidity, and early-life viral exposures shaped serological profiles. We found that infants mounted robust responses to most EPI vaccines, but critical gaps in protection persisted for diphtheria, measles and rubella. Children born to primigravid mothers had lower antibody levels at 8 weeks of age, independent of placental malaria and only partially explained by maternal age. Contrary to expectation, cumulative P. falciparum exposure was positively associated with antibody concentrations to diphtheria and varicella, and concurrent parasitemia was positively correlated with responses to multiple antigens. Seroconversion to rhinovirus C was associated with higher IgG and IgA levels to several vaccines. Together, these findings suggest that common microbial exposures during infancy, including respiratory viruses and P. falciparum may positively modulate vaccine responsiveness.

A cross-sectional study of seroprevalence in Armenia, 2025: measles, mumps, rubella, and diphtheria.

Popova A Y AY, Smirnov V S VS, Egorova S A SA, Atoyan S A SA et al.

Prevention and control of vaccine-preventable infections is a key component of maintaining public health, and the overall state of immunity is the determining factor. To study herd immunity of the Armenian population to measles, rubella, mumps, and diphtheria. The study involved 5,513 individuals from all regions aged from 1 year and above. A cohort of volunteers, stratified into 9 age groups, was formed including by region and activity using a web application. For each infection, the presence and/or levels of immunoglobulin G were determined by the enzyme immunoassay method using Russian-made test systems. The cohort average seroprevalence values for measles, rubella, mumps, and diphtheria were 88.3%, 97.2, 83.2, and 56.3%, respectively. The least protected age groups were: children <5 years (80.7% seropositive) and adults 30-49 years (82-83%) regarding measles; adolescents and adults <49 years (73-79%) regarding mumps; and the older adults (34.4%) regarding diphtheria. Most volunteers had: low or moderate measles Ab levels (0.18-1 IU/mL); high levels of rubella Abs (>200 IU/mL); and a basic protective level of diphtheria toxin Abs (0.1-1 IU/mL). With age, a trend is seen: seropositivity for the viral pathogens (measles, mumps, and rubella) increased to maximum values; and diphtheria seropositivity decreased to minimum values. The level of herd immunity in Armenia is sufficient only for rubella, as confirmed by the absence of cases. Currently, immunity to measles and mumps is present, which prevents outbreaks but may not be fully preventive of sporadic cases. Despite the absence of diphtheria, insufficient protection in older adults makes them a risk group for incidence and severity. However, immunity levels in our study were assessed based only on humoral immunity, which may underrepresent the full immunological response, including that mediated by cellular immunity.