Clinical and immune responses to inactivated influenza A(H1N1)pdm09 vaccine in children

Vaccine Development

This article considers ethical considerations surrounding pediatric vaccine development for pandemic preparedness, examines some historical cases of pediatric vaccines developed during past smallpox, influenza, and 2019 coronavirus disease pandemics, and discusses the current state of vaccine development for pandemic preparedness, including vaccines against smallpox/mpox, influenza, anthrax, and Ebola that are included in the US Strategic National Stockpile and vaccines being developed against priority pathogens identified by the World Health Organization.

Safety and Impact on Training of the Influenza Vaccines in Elite Athletes Participating in the Rio 2016 Olympics

OBJECTIVE

The aim of the study was to evaluate the safety and tolerance of influenza vaccines for the northern and southern hemispheres in Polish elite athletes participating in the Rio 2016 Olympics.

DESIGN

Prospective, observational, cohort study.

SETTING

Institutional level.

PARTICIPANTS

Ninety-seven athletes vaccinated only with the northern hemisphere vaccine; 98 athletes received the southern hemisphere vaccine alone, whereas 39 athletes were vaccinated with both vaccines.

INTERVENTIONS

The athletes were vaccinated with a trivalent, inactivated influenza vaccine recommended for the northern hemisphere 2015/2016 and then with the vaccine recommended for the southern hemisphere 2016. Athletes kept a diary of adverse events and effects (if any) on training for 6 days after vaccination.

MAIN OUTCOME MEASURES

The percentage of general and local adverse events, number of lost or modified training sessions.

RESULTS

Significantly more local adverse events (pain and redness) were found in the group immunized with the vaccine for the northern hemisphere. There were no differences in the frequency of general adverse events and influence on training between groups. Of total 273 athletes who had 1911 training days during 6 days after vaccination, 6 athletes (2.2%) lost 13 training days (0.7%) and 16 athletes (5.9%) had to modify 34 (1.7%) training days within first 2 days after vaccination.

CONCLUSIONS

Athletes tolerated influenza immunization well. If they are going to travel to the other hemisphere during the influenza season, the use of the second influenza vaccine should be advised. Athletes should anticipate modification of trainings for 2 days after vaccination.

Exploration and Ethical Analysis of Open-Label Pediatric Vaccine Trials in a Pandemic

Young children will ultimately need to be vaccinated to stop the spread of coronavirus disease 2019 (COVID-19). Initial studies of vaccine were performed in adults. Randomized controlled trials are the gold standard. In the COVID-19 pandemic, many questions need to be answered about the ethics and feasibility of these trials. Given the harms of the COVID-19 pandemic and the now-known efficacy of the vaccines in adults and teens, the question of whether clinical equipoise exists for a placebo-controlled trial of vaccines in younger children remains. Parents may be reluctant to enroll children in these trials because they want their child to receive the vaccine or because they are worried about vaccines or clinical trials in general. One option for gathering data on tolerability and efficacy in children would be to use a nonrandomized trial to enroll parents willing to vaccinate their children and those who are hesitant. We discuss the advantages and disadvantages of such an open-label trial that could provide guidance for future pandemics. (Clin Ther. 2021;XX:XXX-XXX) © 2021 Elsevier HS Journals, Inc.

The COVID-19 mRNA Vaccines and the Pandemic: Do They Represent the Beginning of the End or the End of the Beginning?

In December 2020, the US Food and Drug Administration issued emergency use authorizations for two mRNA vaccines against coronavirus disease 2019. These vaccines represent an incredible scientific achievement and a major step in efforts to bring the global pandemic to a close. However, these vaccines create many logistical challenges that limit just how far-reaching their impact can be. This commentary reviews how these vaccines offer immunity, summarizes the Phase III trial results, and offers a discussion of the challenges that remain after these vaccines are introduced for widespread use.

The CTA1-DD adjuvant strongly potentiates follicular dendritic cell function and germinal center formation, which results in improved neonatal immunization

Vaccination of neonates and young infants is hampered by the relative immaturity of their immune systems and the lack of safe and efficacious vaccine adjuvants. Immaturity of the follicular dendritic cells (FDCs), in particular, appears to play a critical role for the inability to stimulate immune responses. Using the CD21mT/mG mouse model we found that at 7 days of life, FDCs exhibited a mature phenotype only in the Peyer´s patches (PP), but our unique adjuvant, CTA1-DD, effectively matured FDCs also in peripheral lymph nodes following systemic, as well as mucosal immunizations. This was a direct effect of complement receptor 2-binding to the FDC and a CTA1-enzyme-dependent enhancing effect on gene transcription, among which CR2, IL-6, ICAM-1, IL-1β, and CXCL13 encoding genes were upregulated. This way we achieved FDC maturation, increased germinal center B-cell- and Tfh responses, and enhanced specific antibody levels close to adult magnitudes. Oral priming immunization of neonates against influenza infection with CTA1-3M2e-DD effectively promoted anti-M2e-immunity and significantly reduced morbidity against a live virus challenge infection. To the best of our knowledge, this is the first study to demonstrate direct effects of an adjuvant on FDC gene transcriptional functions and the subsequent enhancement of neonatal immune responses.

Overcoming the Neonatal Limitations of Inducing Germinal Centers through Liposome-Based Adjuvants Including C-Type Lectin Agonists Trehalose Dibehenate or Curdlan

Neonates and infants are more vulnerable to infections and show reduced responses to vaccination. Consequently, repeated immunizations are required to induce protection and early life vaccines against major pathogens such as influenza are yet unavailable. Formulating antigens with potent adjuvants, including immunostimulators and delivery systems, is a demonstrated approach to enhance vaccine efficacy. Yet, adjuvants effective in adults may not meet the specific requirements for activating the early life immune system. Here, we assessed the neonatal adjuvanticity of three novel adjuvants including TLR4 (glucopyranosyl lipid adjuvant-squalene emulsion), TLR9 (IC31^®), and Mincle (CAF01) agonists, which all induce germinal centers (GCs) and potent antibody responses to influenza hemagglutinin (HA) in adult mice. In neonates, a single dose of HA formulated into each adjuvant induced T follicular helper (T_FH) cells. However, only HA/CAF01 elicited significantly higher and sustained antibody responses, engaging neonatal B cells to differentiate into GCs already after a single dose. Although antibody titers remained lower than in adults, HA-specific responses induced by a single neonatal dose of HA/CAF01 were sufficient to confer protection against influenza viral challenge. Postulating that the neonatal adjuvanticity of CAF01 may result from the functionality of the C-type lectin receptor (CLR) Mincle in early life we asked whether other C-type lectin agonists would show a similar neonatal adjuvanticity. Replacing the Mincle agonist trehalose 6,6′-dibehenate by Curdlan, which binds to Dectin-1, enhanced antibody responses through the induction of similar levels of T_FH, GCs and bone marrow high-affinity plasma cells. Thus, specific requirements of early life B cells may already be met after a single vaccine dose using CLR-activating agonists, identified here as promising B cell immunostimulators for early life vaccines when included into cationic liposomes.

Long-term seroprotective response of trivalent seasonal influenza vaccine in HIV-infected children, regardless of immunogenicity before immunisation

Influenza vaccination can reduce disease in HIV-infected children. The durability of the antibody response after trivalent influenza vaccine is important for management. The aim of this prospective study was to assess the durability of seroprotection for trivalent influenza vaccine strains and the factors effecting seroprotective response regardless of immunogenicity before trivalent influenza vaccine at one and six months after immunisation. Hemagglutination inhibition assay was done at one and six months. Seventy-five HIV-infected children were enrolled after vaccination. Four children were lost to follow-up. None of the children had confirmed influenza infection between immunisation and hemagglutination inhibition at six months after influenza vaccination. Seventy-one children were included in the final analysis and immunogenicity of trivalent influenza vaccine strains at one and six months. Of these, 27 (38%) had complete seroprotection (Group A) and 44 (62%) had non-complete seroprotection (Group B). Sex, age and the body mass index of both groups were not different from each other (p > 0.05). There was a higher mean CD4 level and more children with RNA ≤40 copies/mL among Group A compared with Group B (p < 0.05). Other factors did not differ significantly. The durability of the seroprotective response after trivalent influenza vaccine was associated with a high CD4 level and virological suppression before vaccination.