"Let there be light": the role of vitamin D in the immune response to vaccines

Association of systemic vitamin D on the course of dengue virus infection in adults: a single-centre dengue cohort study at a large institution in Singapore

INTRODUCTION

Host immune responses may impact dengue severity in adults. Vitamin D has multiple immunomodulatory effects on innate and adaptive immunity.

METHODS

We evaluated the association between systemic 25-hydroxyvitamin D [25-(OH) D] and dengue disease severity in adults. We measured plasma for total 25-(OH) D levels with an electrochemiluminescence immunoassay using stored samples from participants with laboratory-confirmed dengue, who were prospectively enrolled in 2012-2016 at our institution.

RESULTS

A total of 80 participants (median age 43 years) were enrolled in the study. Six participants had severe dengue based on the World Health Organization (WHO) 1997 criteria (i.e. dengue haemorrhagic fever/dengue shock syndrome) and another six had severe dengue based on the WHO 2009 criteria. Median 25-(OH) D at the acute phase of dengue was 6.175 (interquartile range 3.82-8.21, range 3.00-15.29) mcg/L in all participants. The 25-(OH) D showed an inverse linear trend with severe dengue manifestations based on the WHO 2009 criteria (adjusted risk ratio 0.72, 95% confidence interval 0.57-0.91, P < 0.01) after adjustment for age, gender and ethnicity.

CONCLUSION

Limited studies have evaluated the role of systemic 25-(OH) D on dengue severity. Our study found low systemic 25-(OH) D was associated with increased dengue disease severity, particularly for severe bleeding that was not explained by thrombocytopenia. Further studies investigating the underlying immune mechanisms and effects on the vascular endothelium are needed.

Vitamin D Levels as a Potential Modifier of Eosinophilic Esophagitis Severity in Adults

BACKGROUND

Vitamin D deficiency is associated with atopic and immune-mediated diseases but has not been extensively assessed in eosinophilic esophagitis (EoE). We aimed to assess if vitamin D levels in newly diagnosed EoE patients were lower than in non-EoE controls and examine levels in relation to EoE clinical features.

METHODS

This secondary analysis of a prospective cohort study used data and biosamples from adults who underwent outpatient esophagogastroduodenoscopy. Before each procedure, blood was obtained and stored at -80oC. Serum 25-hydroxy-vitamin D3 (25(OH)D3) was measured by ELISA. Levels for cases and controls were compared at baseline. Within cases, 25(OH)D3 levels were compared for clinical, endoscopic, and histologic measures.

RESULTS

We analyzed 40 EoE and 40 non-EoE controls. Mean serum 25(OH)D3 level was slightly lower in EoE patients than controls (30.9 ± 15.3 ng/mL vs. 35.9 ± 15.4; p = 0.15). After controlling for age, sex, and race, adjusted levels were 10.8 ng/mL lower in EoE patients (95% CI: -19.0, -2.5), but 25(OH)D3 deficiency (< 20ng/mL) was similar in cases and controls (20% vs. 15%; p = 0.56). Levels of 25(OH)D3 were not associated with differences in clinical or endoscopic features of EoE, and EREFS and eosinophil counts did not significantly correlate with 25(OH)D3 levels (R of -0.28 [p = 0.08] and - 0.01 [p = 0.93], respectively). 25(OH)D3 levels were lower in EoE cases with lamina propria fibrosis (23.2 ± 9.6 vs. 45.0 ± 17.7; p = 0.03).

CONCLUSIONS

After adjusting for age, sex, and race, 25(OH)D3 levels were lower in EoE cases than controls, but deficiency was not common. 25(OH)D3 levels were generally similar across most EoE disease features.

Does native vitamin D, or active vitamin D modulate the neutralising antibody responses to COVID-19 vaccination in haemodialysis patients?

INTRODUCTION

Several studies have reported that patients with low levels of Vitamin D3 have impaired responses to vaccination, including COVID-19 vaccines, so we reviewed the response to COVID-19 vaccination in haemodialysis patients, who typically have reduced Vitamin D3 levels.

METHODS

The inhibitory antibody (IC50) responses to several COVID-19 variants following vaccination in a cohort of United Kingdom haemodialysis patients receiving two vaccinations between March 2021 and May 2021 were reviewed.

RESULTS

A total of 183 haemodialysis patients, 65.5% male, mean age 65.6 ± 14.1 years, 46.4% diabetic, 42.1% white ethnicity, body mass index 26.9 ± 6.5 kg/m2 dialysis vintage 36.2 (18.3-69.3) months were studied. Following the first vaccination, the median IgG microneutralisation IC50 response was undetectable for all variants (wild-type, alpha, beta and delta). Follow-up after the second vaccination showed that the microneutralisation response to all variants increased and was greater for the wild-type variant compared to alpha, beta and delta, all p < 0.001, There were no differences comparing the IC50 responses according to 25-Vitamin D3 levels, and the prescription of activated Vitamin D. Although patients who had previously tested positive for COVID-19 prescribed higher doses of alfacalcidol had higher seroprotection responses to the alpha (χ2 = 15, p = 0.002) and beta variants. (χ2 = 13, p = 0.005).

CONCLUSIONS

The response to COVID-19 vaccination was reduced in our elderly haemodialysis patients compared to younger less frail patients, however there was no overall demonstrable effect of either 25-Vitamin D3 levels or the prescription of activated forms of Vitamin D on the immune response following vaccination against COVID-19, unless patients had previously tested positive for COVID-19.

Vaccinomics and adversomics: key elements for a personalized vaccinology

Vaccines are one of the most important and effective tools in the prevention of infectious diseases and research about all the aspects of vaccinology are essential to increase the number of available vaccines more and more safe and effective. Despite the unquestionable value of vaccinations, vaccine hesitancy has spread worldwide compromising the success of vaccinations. Currently, the main purpose of vaccination campaigns is the immunization of whole populations with the same vaccine formulations and schedules for all individuals. A personalized vaccinology approach could improve modern vaccinology counteracting vaccine hesitancy and giving great benefits for human health. This ambitious purpose would be possible by facing and deepening the areas of vaccinomics and adversomics, two innovative areas of study investigating the role of a series of variables able to influence the immune response to vaccinations and the development of serious side effects, respectively. We reviewed the recent scientific knowledge about these innovative sciences focusing on genetic and non-genetic basis involved in the individual response to vaccines in terms of both immune response and side effects.

Exploring the Effects of Vitamin D and Vitamin A Levels on the Response to COVID-19 Vaccine

COVID-19 vaccines were developed at an unprecedented speed in history. The factors affecting the response to COVID-19 vaccines are not clear. Herein, the effects of vitamin D and vitamin A (retinol) levels on the response to the BNT162b2 vaccine were explored. A total of 124 vaccine recipients were recruited from the general population attending vaccination centers in Irbid, Jordan. Blood samples were collected immediately before receiving the first vaccine dose (D0) and three weeks later (D21). Baseline (D0) levels of 25-hydroxyvitamin D [25(OH)D], retinol, and SARS-CoV-2 S1 IgG antibodies were measured with ELISA. The response to the BNT162b2 vaccine was tested by measuring the levels and avidity of SARS-CoV-2 S1 IgG antibodies on D21. The participants were divided into two groups, unexposed and exposed, based on the D0 SARS-CoV-2 antibody results. No significant correlation was found between the levels of 25(OH)D or retinol and the levels, avidity, or fold increase of antibodies in both groups. Similarly, no significant difference in antibody response was found between 25(OH)D status groups, retinol status groups, or combined status groups. These findings show that the baseline vitamin D or vitamin A levels have no effect on the short-term response to a single dose of BNT162b2 vaccine.

Impact of vitamin D3 supplementation on COVID-19 vaccine response and immunoglobulin G antibodies in deficient women: A randomized controlled trial

Background

Immune levels were observed by giving vitamin D supplements to vitamin D deficient women who received the COVID-19 vaccine.

Methods

In the research, there were volunteer women who had received two doses of the COVID-19 vaccine who participated for a mean of more than 65 days. Group D (n=14 Pfizer-BioNTech, 2 Sinovac) received 150,000 IU of vitamin D supplementation, but group C (n=14 Pfizer-BioNTech), 3 Sinovac) no support was provided.

Results

When the consumption of vitamin D ends (D group), serum 25-Hydroxy Vitamin D levels were found to increase regularly in the (W3) last measurements (p=0.001). There was no significant difference in immunoglobulin M levels between groups D and C (Control group) (p=0.063). It was observed that the immunoglobulin G levels reached the peak level between the W1 and W2 measurements of the D group (P<0.001) and there were significant differences between the three sizes. Also, no correlation was found between the D group's initial serum immunoglobulin G and 25-Hydroxy Vitamin D levels. However, when the final measurements were examined, a significant positive correlation was found between immunoglobulin G and 25-Hydroxy Vitamin D levels (r=0.558, p=0.031).

Conclusion

It was determined that serum IgG levels increased significantly depending on the duration between those who used vitamin D and those who did not and it was above the initial level for a long time. A positive and significant relationship was found between the last measured immunoglobulin G and 25(OH) D levels while vitamin D supplementation continued.

Trial Registration: This study registered under ClinicalTrials.gov (Identifier no. NCT05447065)

Determination of the fate of Cholecalciferol injected by the basis of 25D3 plasma concentration

Sun exposure in bovines is believed to be the most important route of 25D₃ synthesis in suitable latitudes. In some situations, e.g. breeding systems, solar radiation cannot reach or penetrate into the skin and thus causes the 25D₃ deficiency. Because of the critical effect of vitamin D on the immune and endocrine systems, the plasma must be enriched with 25D₃ in a short period of time. In such a condition, injection of Cholecalciferol has been recommended. However, to our knowledge, the certain dose of Cholecalciferol injection for rapid 25D₃ plasma enrichment has not been verified. On the other hand, it seems that the basis 25D₃ concentration can influence or shift the 25D₃ metabolism at the injection time. In the same line, the present study, designed to induce the different basis 25D₃ concentration in treatment groups, aimed at investigating the effect of Cholecalciferol intramuscularly injection with the intermediate dose (11,000 IU/kg) on the calves' plasma 25D₃ with different basis 25D₃. Besides, an attempt was made to clarify the time that 25D₃ reaches the sufficient concentration after injection in different treatment groups. To do this, twenty calves of 3 to 4 months old were chosen for the farm with semi-industrial elements. Furthermore, the effect of optional sun exposure/deprivation and Cholecalciferol injection on the 25D₃ concentration variations was assayed. To do this, the calves were divided into four groups. Groups A and B were unconstrained to choose sun to expose or shadow in a semi-roofed place, but groups C and D were restricted to the completely dark barn. The interference of the digestive system in supplying vitamin D was minimized through dietary. All groups had a different basic concentration (25D₃) on the day 21 of the experiment. At this time, groups A and C received the intermediate dose of (11,000 IU/kg) Cholecalciferol intramuscularly (IM). After Cholecalciferol injection, the effects of basis 25D₃ concentration on the details of variation and fate of plasma concentration of 25D₃ were investigated. The data collected from the two groups C and D showed that sun deprivation without any vitamin D supplementation, could rapidly and severely deplete the plasma from 25D₃. Cholecalciferol injection could not immediately increase the 25D₃ in the groups C and A. However, this injection enriches the 25D₃ to sufficient value after two weeks if the basis 25D₃ of plasma is insufficient, i.e. less than 30 ng/mL. Moreover, the injection of Cholecalciferol could not significantly increase the 25D₃ concentration in the group A that had a sufficient basis 25D₃ concentration. Therefore, it is concluded that the variation of 25D₃ in plasma, after injection of Cholecalciferol, depends on its basic level at the time of injection.

Towards a Future of Personalized Vaccinology: Study on Individual Variables Influencing the Antibody Response to the COVID-19 Vaccine

The COVID-19 pandemic has hugely impacted many different aspects of human health, and vaccination is one of the most effective weapons to manage it. However, many different factors, such as age, gender, comorbidities and lifestyles, play a role in the response to infections and vaccines. We carried out this study to evaluate the potential role played by some individual factors in the production of anti-COVID-19 antibodies in the light of personalized and future vaccinology. We conducted an observational study consisting of a retrospective phase, exploiting previous data about anti-COVID-19 antibody responses, with a prospective phase to investigate individual variables through the use of a questionnaire. The antibody response after the COVID-19 vaccination was inversely related to old age, increased BMI and the number of smoking years, while a positive correlation was found with moderate alcohol consumption and especially with circulating levels of vitamin D, as clearly shown by the multivariate regression analysis. Our study showed that a number of variables are involved in the COVID-19 vaccine antibody response. These findings are very important and can be considered in the light of a future and personalized vaccinology.

Can vitamin D status influence seroconversion to SARS-COV2 vaccines?

Existing data indicate an association between vitamin D deficiency and increased severity of respiratory distress due to COVID-19 infection, especially in high-risk populations. To date, the effect of vitamin D on immunogenicity to SARS-CoV-2 vaccines has been investigated solely in young healthcare workers in a few studies, yielding conflicting findings, yet highlighting that the response to immunization is inversely related to age. Vitamin D status can potentially influence the antibody titers in people with a previous (or naïve) SARS-CoV-2 infection and vaccination, given its role in immune regulatory functions. From this standpoint, vitamin D supplementation can help reduce the risk of SARS-CoV-2 infection, COVID-19 severity/mortality and rebalance immunological function, particularly in subjects with vigorous T lymphocyte responses to COVID-19. However, more research is needed to establish a correlation between vitamin D status and the generation of protective serological responses to SARS-CoV-2 vaccination.

Lack of relationship between 25-hydoxyvitamin D concentration and a titer of antibodies to hepatitis B surface antigen in children under 12 years of age

The effect of vitamin D levels on the response to the hepatitis B vaccine in childhood and the induced levels of antibodies against the hepatitis B surface antigen (anti-HBs) is not yet well understood. The study aimed to investigate the relationship between age, serum 25-hydroxyvitamin D (25(OH)D) concentration and anti-HBs titer among children under 12 years old. Serum 25(OH)D concentration and anti-HBs titer were determined in 352 healthy Caucasian children with the average age of 4.2 (2.5; 6.3) years. All children were vaccinated with 3 doses of hepatitis B vaccine (Engerix-B, GlaxoSmithKline Pharmaceuticals Limited) in infancy according to the Centers for Disease Control and Prevention recommendations. Only 14.5% of children had an optimal concentration of 25(OH)D ≥ 30 ng/mL and 71.9% children had a seroprotective anti-HBs titer ≥ 10 mIU/mL. Significant negative correlations were found between 25(OH)D, anti-HBs titer and age (r = –0.420, p = 0.000; r = –0.425, p = 0.000, respectively), and a weak positive correlation between 25(OH)D concentration and anti-HBs titer (r = 0.243, p = 0.000). Analysis of six clusters of children demonstrated that age is the main factor affecting anti-HBs titer. One third of children under 12 years of age had nonprotective anti-HBs titer < 10 mIU/mL and around 40% had vitamin D deficiency. We conclude that vitamin D status has no impact on anti-HBs titer in children vaccinated against hepatitis B virus in infancy. Age, so time since the receipt of the last dose of hepatitis B vaccine, is the main factor influencing a decline in anti-HBs titer.

DYNAMIC cohort study evaluating metabolic predictors of influenza vaccine immune response in older adults

Immunosenescence (age-related immune dysfunction) and inflamm-aging contribute to suboptimal immune responses in older adults to standard-dose influenza vaccines, which may be exacerbated in those with metabolic co-morbidities. We sought to investigate metabolic factors/predictors of influenza vaccine immune response in an older adult (age ≥65 years) cohort in Singapore, where influenza typically circulates year-round. The primary outcome for the DYNAMIC prospective cohort study was haemagglutination-inhibition titer (HAI) response to each of the trivalent inactivated influenza vaccine strains at day 28 (D28) compared to baseline (D0), as assessed by seroconversion and D28/D0 log2 HAI fold rise. Baseline blood samples were tested for total Vitamin D (25-(OH) D) levels. We enrolled 234 participants in June-Dec 2017. Two hundred twenty completed all study visits. The median age was 71 [IQR 68-75] years, 67 (30.5%) had diabetes mellitus (DM), and the median BMI was 24.9 [IQR 22.2-27.8] kg/m². Median baseline totals 25-(OH) D was 29 [IQR: 21-29] ng/ml. Age, DM, obesity, and baseline 25-(OH) D were not associated with HAI fold rise in multivariable analysis. More recent prior influenza vaccination and higher baseline HAI titers were associated with lower HAI fold rise for influenza A/HK/H3N2. Physical activity was associated with a higher HAI fold rise for influenza A/HK/H3N2 in a dose-response relationship (p-test for trend = 0.015). Older adults with well-controlled metabolic co-morbidities retain HAI response to the influenza vaccine, and physical activity had a beneficial effect on immune response, particularly for influenza A/HK/H3N2.

Serum Antibodies SARS-CoV-2 Spike (S) Protein Receptor-Binding Domain in OBGYN Residents and Effectiveness 3 Months after COVID-19 Vaccination

BACKGROUND: The health care workers are considered as vulnerable people who had higher infecting dose of SARS-CoV-2 infection compared to other society. Among more than 500 deaths of Indonesians physicians, obstetrics and gynecologist (OBGYN) has become the most specialists who died in this pandemic. AIM: The objective of our study is to evaluate the antibodies of SARS-CoV-2 in serum OBGYN residents post-vaccination as well as the presence of infection 3 months after the vaccination. METHODS: A prospective cohort study was conducted in OBGYN residents Universitas Indonesia. Serum antibodies SARS-CoV-2 spike (S) protein receptor-binding domain (RBD) was measured using electrochemiluminescence immunoassay, 21 days after Sinovac vaccination, with basic characteristics being recorded. Within 3 months follow-up, the participants were monthly checked related to post-vaccination infection. RESULTS: The median antibodies SARS-CoV-2 for all participants were 50.72 (19.09–98.57) U/mL. There were 20 residents (24.1%) who had post-vaccination infection within 3 months and dominated by asymptomatic to mild symptoms. Body mass index (r = –0.221, p = 0.044) and sleep hours (r = –0.225, p = 0.041) were found to be inversely correlated with antibodies SARS-CoV-2 S RBD. CONCLUSION: Antibodies SARS-CoV-2 S RBD found to be correlated with BMI and sleep hours. The 3-month post-vaccine infection among OBGYN residents was almost similar to Jakarta’s positivity rate and the efficacy rate was higher than expected by National Agency of Drug and Food Control.

Dietary Intake and Pneumococcal Vaccine Response Among Children (5–7 Years) in Msambweni Division, Kwale County, Kenya

Background

Vaccine and sufficient food availability are key factors for reducing pneumonia outbreaks in sub-Saharan Africa.

Methods

In this study, the 10-valent pneumococcal conjugate vaccine (Synflorix® or PCV10) was administered to a child cohort (5–7 years old, n = 237) in Msambweni, Kenya, to determine relationships between dietary intake, nutritional/socioeconomic status of mothers/caregivers, and vaccine response. 7-day food frequency questionnaire (FFQ), dietary diversity score (DDS) and single 24-h dietary recall were used to address participants' dietary assessment and nutritional status. Individual food varieties were recorded and divided into 9 food groups as recommended by Food and Agriculture Organization. Anthropometric measurements, nasopharyngeal swabs and vaccine administration were performed at the initial visit. Participants were followed 4–8 weeks with a blood draw for pneumococcal IgG titers assessed by Luminex assay.

Findings

Chronic malnutrition was prevalent in the cohort (15% stunting, 16% underweight). Unbalanced dietary intake was observed, with mean energy intake 14% below Recommended Dietary Allowances (1,822 Kcal) for 5–7 years age range. 72% of the daily energy was derived from carbohydrates, 18% from fats and only 10% from proteins. Poor anthropometric status (stunting/underweight) was associated with low socioeconomic/educational status and younger mother/caregiver age (p &lt; 0.002). Limited intake of essential micronutrients (vitamins A, E, K) and minerals (calcium, potassium) associated with low consumption of fresh fruits, vegetables, and animal source foods (dairy, meat) was observed and correlated with poor vaccine response (p &lt; 0.001). In contrast, children who consumed higher amounts of dietary fiber, vitamin B1, zinc, iron, and magnesium had adequate vaccine response (p &lt; 0.05). Correlation between higher dietary diversity score (DDS), higher Vitamin E, K, Zinc intake and adequate vaccine response was also observed (p &lt; 0.03).

Interpretation

Overall, this study highlights ongoing food scarcity and malnutrition in Kenya and demonstrates the links between adequate socioeconomic conditions, adequate nutrient intake, and vaccine efficacy.

Association of hepatitis B vaccine response to vitamin D supplementation and ultraviolet B (UVB) exposure during different time intervals in experimental animals

The implications of vitamin D deficiency on the immune system have become clearer in recent years, being associated with less immune response following HBV vaccine. We aimed to elucidate the effect of vitamin D supplementation and UVB exposure on short- and long-term performance of hepatitis B vaccine. Forty-five male rabbits were randomly divided into 3 groups that were immunized with recombinant HBsAg. The first group (group I) represented a negative control group, whereas group III rabbits were administered with commercially available 1,25 (OH)2 vitamin D as an alternative for UVB exposure in group II. Results showed that vitamin D concentrations were significantly higher in UVB exposed group compared to both negative control and vitamin D-supplemented groups during short- and long-time intervals. In addition, means of anti-HBsAg isotypes’ levels and anti-HBsAg IgG avidity% were significantly higher in negative control group compared to other groups during short- and long-time intervals. Moreover, vitamin D serum concentration was positively correlated with anti-HBsAg IgG level and avidity % in both negative control and vitamin D-supplemented groups, while it was negatively correlated with anti-HBsAg IgM level in negative control group. It can be concluded from the above results that UVB radiation may have both augmenting and suppressive effects and that circulating serum vitamin D concentration may have a positive association with premium immune modulation following HBV vaccination.

Age and vitamin D affect the magnitude of the antibody response to the first dose of the SARS-CoV-2 BNT162b2 vaccine

Background

Most approved vaccines utilise a two-dose strategy. To enable larger groups of patients to receive the first dose, the UK government increased the gap between the two doses from three to twelve weeks. Here we report on the immunogenicity of the first dose, including effect of age and vitamin D status on these levels over an 8 week-period.

Methods

Blood samples were collected from healthcare workers (HCW) receiving their first BNT162b2 vaccine dose between January and February 2021. Antibody (Ab) production was measured, prior to and weekly for 4 weeks post immunization, and a final measurement was performed at 8 weeks. Serum vitamin D concentrations were also measured at baseline.

Findings

Immunization of 97 HCW induced an Ab response that peaked 3•2 weeks post immunization to decrease thereafter. Ab levels remained positive at 8 weeks. IgG peak concentration was negatively associated with age (β=-0•440, p<0.001). Response to immunization was also significantly affected by vitamin D status (p=0•022), on average 29•3% greater peak value in individuals with 25(OH)D>50nmol/L. No other variable showed significant effect.

Interpretation

The first dose of BNT162b2 produced Ab levels that remained positive after 8 weeks. Peak was greater in younger subjects and 25(OH)D>50nmol/L was beneficial. Booster campaigns should take into consideration vitamin D status which is at its highest following a period of sunshine exposure or following oral supplementation (400-1000IU daily).

Funding

Abbott Diagnostics Ltd supplied the kits used to quantify the anti-SARS -CoV-2 Spike IgG and technical support as well as provided financial support for sample collections.

Role of vitamin D deficiency and comorbidities in COVID-19

Recent manuscripts described the incidence of vitamin D hypovitaminosis in coronavirus disease 2019 (COVID-19) patients. Vitamin D deficiency is also common in patients with comorbidities that are associated with a poor COVID-19 prognosis. In this letter, we review the literature regarding the association of comorbidities, vitamin D deficiency, and COVID-19.

The Exposome and Immune Health in Times of the COVID-19 Pandemic

Growing evidence supports the importance of lifestyle and environmental exposures-collectively referred to as the 'exposome'-for ensuring immune health. In this narrative review, we summarize and discuss the effects of the different exposome components (physical activity, body weight management, diet, sun exposure, stress, sleep and circadian rhythms, pollution, smoking, and gut microbiome) on immune function and inflammation, particularly in the context of the current coronavirus disease 2019 (COVID-19) pandemic. We highlight the potential role of 'exposome improvements' in the prevention-or amelioration, once established-of this disease as well as their effect on the response to vaccination. In light of the existing evidence, the promotion of a healthy exposome should be a cornerstone in the prevention and management of the COVID-19 pandemic and other eventual pandemics.

"World in motion" - emulsion adjuvants rising to meet the pandemic challenges

Emulsion adjuvants such as MF59 and AS03 have been used for more than two decades as key components of licensed vaccines, with over 100 million doses administered to diverse populations in more than 30 countries. Substantial clinical experience of effectiveness and a well-established safety profile, along with the ease of manufacturing have established emulsion adjuvants as one of the leading platforms for the development of pandemic vaccines. Emulsion adjuvants allow for antigen dose sparing, more rapid immune responses, and enhanced quality and quantity of adaptive immune responses. The mechanisms of enhancement of immune responses are well defined and typically characterized by the creation of an "immunocompetent environment" at the site of injection, followed by the induction of strong and long-lasting germinal center responses in the draining lymph nodes. As a result, emulsion adjuvants induce distinct immunological responses, with a mixed Th1/Th2 T cell response, long-lived plasma cells, an expanded repertoire of memory B cells, and high titers of cross-neutralizing polyfunctional antibodies against viral variants. Because of these various properties, emulsion adjuvants were included in pandemic influenza vaccines deployed during the 2009 H1N1 influenza pandemic, are still included in seasonal influenza vaccines, and are currently at the forefront of the development of vaccines against emerging SARS-CoV-2 pandemic variants. Here, we comprehensively review emulsion adjuvants, discuss their mechanism of action, and highlight their profile as a benchmark for the development of additional vaccine adjuvants and as a valuable tool to allow further investigations of the general principles of human immunity.

The Immunomodulatory Function of Vitamin D, with Particular Reference to SARS-CoV-2

Vaccines are the only way to reduce the morbidity associated to SARS-CoV-2 infection. The appearance of new mutations urges us to increase the effectiveness of vaccines as a complementary alternative. In this context, the use of adjuvant strategies has improved the effectiveness of different vaccines against virus infections such as dengue, influenza, and common cold. Recent reports on patients infected by COVID-19 reveal that low levels of circulating vitamin D correlate with a severe respiratory insufficiency. The immunomodulatory activity of this micronutrient attenuates the synthesis of pro-inflammatory cytokines and at the same time, increases antibody production. Therefore, the present review proposes the use of vitamin D as adjuvant micronutrient to increase the efficacy of vaccines against SARS-CoV-2 infection.

Vaccine-Induced Cellular Immunity against Bordetella pertussis: Harnessing Lessons from Animal and Human Studies to Improve Design and Testing of Novel Pertussis Vaccines

Pertussis ('whooping cough') is a severe respiratory tract infection that primarily affects young children and unimmunised infants. Despite widespread vaccine coverage, it remains one of the least well-controlled vaccine-preventable diseases, with a recent resurgence even in highly vaccinated populations. Although the exact underlying reasons are still not clear, emerging evidence suggests that a key factor is the replacement of the whole-cell (wP) by the acellular pertussis (aP) vaccine, which is less reactogenic but may induce suboptimal and waning immunity. Differences between vaccines are hypothesised to be cell-mediated, with polarisation of Th1/Th2/Th17 responses determined by the composition of the pertussis vaccine given in infancy. Moreover, aP vaccines elicit strong antibody responses but fail to protect against nasal colonisation and/or transmission, in animal models, thereby potentially leading to inadequate herd immunity. Our review summarises current knowledge on vaccine-induced cellular immune responses, based on mucosal and systemic data collected within experimental animal and human vaccine studies. In addition, we describe key factors that may influence cell-mediated immunity and how antigen-specific responses are measured quantitatively and qualitatively, at both cellular and molecular levels. Finally, we discuss how we can harness this emerging knowledge and novel tools to inform the design and testing of the next generation of improved infant pertussis vaccines.

Recent advances of vitamin D in immune, reproduction, performance for pig: a review

Vitamin D (VD) has been reported to play multiple and significant roles in improving pig health via modulating calcium and phosphorus homeostasis, skeletal muscle development and the immune system. Apart from food, photochemical action of 7-dehydrocholesterol in the skin is the main source of this molecule for pigs. The VD from dietary intake or photosynthesized via skin can be absorbed into the liver for hydroxylation, and further hydroxylated into the hormone form of VD (1,25-dihydroxyvitamin D3 or 1,25(OH)2D3) in the kidney. As a sterol hormone, 1,25(OH)2D3 is able to bind with the VD receptor (VDR), and this ligand-receptor complex (VDR/retinoic X receptor) translocates from the cytoplasm into the nucleus to regulate gene expression, thus modulating metabolism. In this review, we summarized the recent studies regarding the non-skeletal health benefits of VD for pigs, and focused on the recent advances in the cellular and molecular mechanisms of VD that affects the immune system and reproductive health. This review provides a reference for future research and application of VD in pigs.

The evident and the hidden factors of vitamin D status in older people during COVID-19 pandemic

Purpose

Considering the COVID-19 pandemic, vitamin D is a target of research and speculation. Lockdown or home isolation reduces sunlight exposition and increases the risk of vitamin D deficiency. Special attention is needed for older people at risk of both severe forms of COVID-19 and vitamin D deficiency. This review aims to highlight the association of vitamin D and COVID-19 in two instances, the direct influence of vitamin D on the immune system, and the indirect risks for other vitamin D deficiency-related diseases, such as musculoskeletal properties in older persons.

Methods

We performed a narrative review.

Results

Whether vitamin D deficiency is associated with COVID-19 poor prognosis, and if vitamin D supplementation may improve the post-infection outcomes is still unclear. In any case, the pandemic generates indirect burden, such as the sequence: home isolation, low sunlight exposition, vitamin D deficiency, and fragility fractures.

Conclusion

Therefore, it is time to debate how to optimize vitamin D status in older people, especially during the COVID-19 pandemic.

Maternal Immunization: Nature Meets Nurture

Vaccinating women in pregnancy (i.e., maternal immunization) has emerged as a promising tool to tackle infant morbidity and mortality worldwide. This approach nurtures a 'gift of nature,' whereby antibody is transferred from mother to fetus transplacentally during pregnancy, or postnatally in breast milk, thereby providing passive, antigen-specific protection against infections in the first few months of life, a period of increased immune vulnerability for the infant. In this review, we briefly summarize the rationale for maternal immunization programs and the landscape of vaccines currently in use or in the pipeline. We then direct the focus to the underlying biological phenomena, including the main mechanisms by which maternally derived antibody is transferred efficiently to the infant, at the placental interface or in breast milk; important research models and methodological approaches to interrogate these processes, particularly in the context of recent advances in systems vaccinology; the potential biological and clinical impact of high maternal antibody titres on neonatal ontogeny and subsequent infant vaccine responses; and key vaccine- and host-related factors influencing the maternal-infant dyad across different environments. Finally, we outline important gaps in knowledge and suggest future avenues of research on this topic, proposing potential strategies to ensure optimal testing, delivery and implementation of maternal vaccination programs worldwide.

Effects of Vitamin D2 (Ergocalciferol) and D3 (Cholecalciferol) on Atlantic Salmon (Salmo salar) Primary Macrophage Immune Response to Aeromonas salmonicida subsp. salmonicida Infection

Vitamin D₂ (ergocalciferol) and vitamin D₃ (cholecalciferol) are fat-soluble secosteroid hormones obtained from plant and animal sources, respectively. Fish incorporates vitamin D₂ and D₃ through the diet. In mammals, vitamin D forms are involved in mineral metabolism, cell growth, tissue differentiation, and antibacterial immune response. Vitamin D is an essential nutrient in aquafeeds for finfish. However, the influence of vitamin D on fish cell immunity has not yet been explored. Here, we examined the effects of vitamin D₂ and vitamin D₃ on Salmo salar primary macrophage immune response to A. salmonicida subspecies salmonicida infection under in vitro conditions. We determined that high concentrations of vitamin D₂ (100,000 ng/ml) and D₃ (10,000 ng/ml) affect the growth of A. salmonicida and decrease the viability of S. salar primary macrophages. In addition, we determined that primary macrophages pre-treated with a biologically relevant concentration of vitamin D₃ for 24 h showed a decrease of A. salmonicida infection. In contrast, vitamin D₂ did not influence the antibacterial activity of the S. salar macrophages infected with A. salmonicida. Vitamin D₂ and D₃ did not influence the expression of canonical genes related to innate immune response. On the other hand, we found that A. salmonicida up-regulated the expression of several canonical genes and suppressed the expression of leukocyte-derived chemotaxin 2 (lect-2) gene, involved in neutrophil recruitment. Primary macrophages pre-treated for 24 h with vitamin D₃ counteracted this immune suppression and up-regulated the transcription of lect-2. Our results suggest that vitamin D₃ affects A. salmonicida attachment to the S. salar primary macrophages, and as a consequence, the A. salmonicida invasion decreased. Moreover, our study shows that the positive effects of vitamin D₃ on fish cell immunity seem to be related to the lect-2 innate immunity mechanisms. We did not identify positive effects of vitamin D₂ on fish cell immunity. In conclusion, we determined that the inactive form of vitamin D₃, cholecalciferol, induced anti-bacterial innate immunity pathways in Atlantic salmon primary macrophages, suggesting that its utilization as a component of a healthy aquafeed diet in Atlantic salmon could enhance the immune response against A. salmonicida.

Serum Vitamin D and Immunogenicity of Influenza Vaccination in the Elderly

Vaccination is the most effective preventive measure that reduces the risk of influenza and post-influenza complications. It prevents influenza-related hospitalizations and deaths in 50-60% and about 80% of patients aged over 65, respectively. There is the clinical plausibility of the association between serum vitamin D (VIT D) content and viral respiratory infections. In this study, we addressed the issue of a vitamin D modulatory effect on the immune response to seasonal influenza vaccination in elderly persons. The study comprised 96 participants aged 60-75 during the 2016/17 epidemic season. After the determination of the baseline content of VIT D and anti-hemagglutinin antibodies (H1, H3, and HB), participants were vaccinated with a trivalent vaccine. The content of the anti-hemagglutinin antibodies was rechecked 4-5 weeks afterward, showing inappreciable alterations. The negative findings of this study make the influence of serum VIT D content on the immunogenicity of influenza vaccination highly unlikely in elderly persons.

Baseline Serum Vitamin A and D Levels Determine Benefit of Oral Vitamin A&D Supplements to Humoral Immune Responses Following Pediatric Influenza Vaccination

Maximizing vaccine efficacy is critical, but previous research has failed to provide a one-size-fits-all solution. Although vitamin A and vitamin D supplementation studies have been designed to improve vaccine efficacy, experimental results have been inconclusive. Information is urgently needed to explain study discrepancies and to provide guidance for the future use of vitamin supplements at the time of vaccination. We conducted a randomized, blinded, placebo-controlled study of influenza virus vaccination and vitamin supplementation among 2 to 8 (inclusive) year old children over three seasons, including 2015–2016 (n = 9), 2016–2017 (n = 44), and 2017–2018 (n = 26). Baseline measurements of vitamins A and D were obtained from all participants. Measurements were of serum retinol, retinol-binding protein (RBP, a surrogate for retinol), and 25-hydroxyvitamin D (25(OH)D). Participants were stratified into two groups based on high and low incoming levels of RBP. Children received two doses of the seasonal influenza virus vaccine on days 0 and 28, either with an oral vitamin supplement (termed A&D; 20,000 IU retinyl palmitate and 2000 IU cholecalciferol) or a matched placebo. Hemagglutination inhibition (HAI) antibody responses were evaluated toward all four components of the influenza virus vaccines on days 0, 28, and 56. Our primary data were from season 2016–2017, as enrollment was highest in this season and all children exhibited homogeneous and negative HAI responses toward the Phuket vaccine at study entry. Responses among children who entered the study with insufficient or deficient levels of RBP and 25(OH)D benefited from the A&D supplement (p < 0.001 for the day 28 Phuket response), whereas responses among children with replete levels of RBP and 25(OH)D at baseline were unaffected or weakened (p = 0.02 for the day 28 Phuket response). High baseline RBP levels associated with high HAI titers, particularly for children in the placebo group (baseline RBP correlated positively with Phuket HAI titers on day 28, r = 0.6, p = 0.003). In contrast, high baseline 25(OH)D levels associated with weak HAI titers, particularly for children in the A&D group (baseline 25(OH)D correlated negatively with Phuket HAI titers on day 28, r = −0.5, p = 0.02). Overall, our study demonstrates that vitamin A&D supplementation can improve immune responses to vaccines when children are vitamin A and D-insufficient at baseline. Results provide guidance for the appropriate use of vitamins A and D in future clinical vaccine studies.

Factors That Influence the Immune Response to Vaccination

There is substantial variation between individuals in the immune response to vaccination. In this review, we provide an overview of the plethora of studies that have investigated factors that influence humoral and cellular vaccine responses in humans. These include intrinsic host factors (such as age, sex, genetics, and comorbidities), perinatal factors (such as gestational age, birth weight, feeding method, and maternal factors), and extrinsic factors (such as preexisting immunity, microbiota, infections, and antibiotics). Further, environmental factors (such as geographic location, season, family size, and toxins), behavioral factors (such as smoking, alcohol consumption, exercise, and sleep), and nutritional factors (such as body mass index, micronutrients, and enteropathy) also influence how individuals respond to vaccines. Moreover, vaccine factors (such as vaccine type, product, adjuvant, and dose) and administration factors (schedule, site, route, time of vaccination, and coadministered vaccines and other drugs) are also important. An understanding of all these factors and their impacts in the design of vaccine studies and decisions on vaccination schedules offers ways to improve vaccine immunogenicity and efficacy.

Exposure to Ultraviolet Radiation in the Modulation of Human Diseases

This review focuses primarily on the beneficial effects for human health of exposure to ultraviolet radiation (UVR). UVR stimulates anti-inflammatory and immunosuppressive pathways in skin that modulate psoriasis, atopic dermatitis, and vitiligo; suppresses cutaneous lesions of graft-versus-host disease; and regulates some infection and vaccination outcomes. While polymorphic light eruption and the cutaneous photosensitivity of systemic lupus erythematosus are triggered by UVR, polymorphic light eruption also frequently benefits from UVR-induced immunomodulation. For systemic diseases such as multiple sclerosis, type 1 diabetes, asthma, schizophrenia, autism, and cardiovascular disease, any positive consequences of UVR exposure are more speculative, but could occur through the actions of UVR-induced regulatory cells and mediators, including 1,25-dihydroxy vitamin D₃, interleukin-10, and nitric oxide. Reduced UVR exposure is a risk factor for the development of several inflammatory, allergic, and autoimmune conditions, including diseases initiated in early life. This suggests that UVR-induced molecules can regulate cell maturation in developing organs.

Vitamin D and Influenza-Prevention or Therapy?

Vitamin D generates many extraskeletal effects due to the vitamin D receptor (VDR) which is present in most tissues throughout the body. The possible role of vitamin D in infections is implied from its impact on the innate and adaptive immune responses. A significant effect is also the suppression of inflammatory processes. Because vitamin D could be acknowledged as a “seasonal stimulus”, as defined by R. Edgar Hope-Simpson, it would be crucial to prove it from a potential easy and cheap prophylaxis or therapy support perspective as far as influenza infections are concerned. The survey of the literature data generates some controversies and doubts about the possible role of vitamin D in the prevention of influenza virus. The most important point is to realise that the broad spectrum of this vitamin’s activity does not exclude such a possibility. According to most of the authors, more randomized controlled trials with effective, large populations are needed to explore the preventive effect of vitamin D supplementation on viral influenza infections.

Taking a bite out of nutrition and arbovirus infection

Nutrition is a key factor in host–pathogen defense. Malnutrition can increase both host susceptibility and severity of infection through a number of pathways, and infection itself can promote nutritional deterioration and further susceptibility. Nutritional status can also strongly influence response to vaccination or therapeutic pharmaceuticals. Arthropod-borne viruses (arboviruses) have a long history of infecting humans, resulting in regular pandemics as well as an increasing frequency of autochthonous transmission. Interestingly, aside from host-related factors, nutrition could also play a role in the competence of vectors required for transmission of these viruses. Nutritional status of the host and vector could even influence viral evolution itself. Therefore, it is vital to understand the role of nutrition in the arbovirus lifecycle. This Review will focus on nutritional factors that could influence susceptibility and severity of infection in the host, response to prophylactic and therapeutic strategies, vector competence, and viral evolution.

As the old adage goes, you are what you eat. Proper nutrition is a cornerstone of health, and malnutrition can seriously impair the function of the immune system, resulting in increased infections or a more severe disease. Imbalanced or inadequate nutrition can also affect responses to vaccines or drugs that are vital for protection and treatment against viruses. A mosquito is also a product of what it eats. Nutrition during development and adult lifecycle can affect the feeding behavior of mosquitoes, thereby affecting transmission of viral diseases. Arthropod-borne viruses (arboviruses) are a major global health concern, especially in areas impacted by malnutrition. Understanding how nutrition can affect both humans and mosquitoes in the context of these viruses is vital to combating these diseases.

Healthy changes in some cardiometabolic risk factors accompany the higher summertime serum 25-hydroxyvitamin D concentrations in Iranian children: National Food and Nutrition Surveillance

OBJECTIVE

To investigate seasonal variations of vitamin D status at different latitudes and if these changes are accompanied by corresponding variations in certain health parameters in children living in a broad latitudinal range in Iran.

DESIGN

Longitudinal study.

SUBJECTS

In total, 530 apparently healthy children aged 5-18 years were randomly selected from six regions of Iran with a latitudinal gradient from 29°N to 37·5°N. All anthropometric and biochemical assessments were performed twice during a year (summer, winter). High BMI (Z-score >1), low HDL cholesterol (150 mg/dl) were considered cardiometabolic risk factors.

RESULTS

Serum 25-hydroxyvitamin D (25(OH)D) showed between-season variation, with significantly higher concentrations (mean (sd)) in summer v. winter (43 (29) v. 27 (18) nmol/l; P33°N v. <33°N: 4·5; 0·09, 9·0; P=0·04) were predictors of change of serum 25(OH)D between two seasons.

CONCLUSIONS

Summertime improvement of vitamin D status was accompanied by certain improved cardiometabolic risk factors, notably serum TAG, total cholesterol and BMI, in children.

No Positive Association between Vitamin D Level and Immune Responses to Hepatitis B and Streptococcus pneumoniae Vaccination in HIV-Infected Adults

Objective

To assess whether higher 25-hydroxyvitamin D (25OHD) levels are associated with subsequent better immune responses to hepatitis B and Streptococcus pneumoniae vaccination in HIV-infected patients.

Methods

25OHD was measured on stored baseline plasma samples from two randomized vaccine trials in HIV-infected adults: the ANRS HB03 VIHVAC B trial and an immunological sub-study of the ANRS 114-PNEUMOVAC trial. In ANRS HB03 VIHVAC B, participants received three or four doses of recombinant HBV vaccine strategies. Anti-HBs IgG titers were measured four weeks after the last injection. Associations between baseline 25OHD levels and ordered IgG response categories were analyzed in multivariable proportional odds models. In the ANRS 114-PNEUMOVAC sub-study, two strategies of pneumococcal vaccination were tested, cellular immune responses were measured at repeated time points, and IgG responses four weeks after the last vaccine injection. Exploratory statistical analyses were performed on this sub-study data set.

Results

Three hundred and thirty-nine ANRS HB03 VIHVAC B and 25 ANRS 114-PNEUMOVAC sub-study participants were included in the analyses. Median age in each of the two studies was 43 years, 68% were male, and 77–92% on antiretroviral treatment. Median 25OHD level was 18 ng/mL (IQR: 12–25) and 24 ng/mL (IQR: 13–32) in the two trial populations, respectively. In the multivariable model, there was no significant association between baseline 25OHD level and vaccine responses in ANRS HB03 VIHVAC B (proportional odds ratio 0.83 per 10 ng/mL 25OHD increase; 95% confidence interval 0.65–1.07, p = 0.14). Exploratory analyses of ANRS 114-PNEUMOVAC showed consistent results.

Conclusion

This study does not support a positive association between 25OHD and immune responses to hepatitis B or pneumococcal vaccination in HIV-infected patients.