Evaluation of the BNT162b2 Covid-19 Vaccine in Children 5 to 11 Years of Age

Vaccinating Children against SARS-CoV-2: A Literature Review and Survey of International Experts to Assess Safety, Efficacy and Perceptions of Vaccine Use in Children

Introduction: The balance of risks and benefits of COVID-19 vaccination in children is more complex than in adults with limited paediatric data resulting in no global consensus on whether all healthy children should be vaccinated. We sought to assess the safety, efficacy, and effectiveness of childhood vaccination against SARS-CoV-2, as well as better understanding perceptions of vaccination in parents and vaccine experts. Methods: We performed a literature review for COVID-19 vaccine safety, efficacy, effectiveness, and perceptions. We searched international safety databases for safety data and developed an electronic survey to elicit country-specific COVID-19 immunisation data, including vaccine regulations, policies, rates, and public attitudes solicited from vaccine experts. Results: Nine studies were included in the final safety analysis. Local reactions were frequently reported across all studies and vaccine types. Adverse events reported to surveillance systems tended to be non-serious, and commonly included injection site reactions and dizziness. Twenty-three studies reported immunogenicity, efficacy, and effectiveness data. There were nine randomised control trials of six different vaccine types, which showed seroconversion of neutralising antibodies in vaccinated children ranging from 88% to 100%. The vaccine efficacy for Pfizer and Moderna vaccines ranged from 88% to 100%. There were 118 survey responses representing 55 different countries. Reported vaccination rates ranged from <1% to 98%. Most respondents described “mixed opinions” regarding paediatric vaccination policies in their country. By region, a more positive public attitude towards vaccination correlated with higher vaccination rates. Discussion: In this mixed-methods review, we have found evidence that vaccination against COVID-19 in children is safe, efficacious, and effective. Overall, the combined evidence from both the literature review and survey highlights the need for further data on both the safety and effectiveness of COVID-19 vaccinations in children.

A narrative review of vaccine pharmacovigilance during mass vaccination campaigns: Focus on myocarditis and pericarditis after COVID-19 mRNA vaccination

Vaccines have had a tremendous impact on reducing the burden of infectious diseases; however, they have the potential to cause adverse events following immunization (AEFIs). Prelicensure clinical trials are limited in their ability to detect rare AEFIs that may occur in less than one per thousand individuals. While postmarketing surveillance systems have shown COVID-19 mRNA vaccines to be safe, they led to the identification of rare cases of myocarditis and pericarditis after COVID-19 vaccination that were not initially detected in clinical trials. In this narrative review, we highlight concepts of vaccine pharmacovigilance during mass vaccination campaigns and compare the approaches used in the context of myocarditis and pericarditis following COVID-19 vaccination to historical examples. We describe mechanisms of passive and active surveillance, their strengths and limitations, and how they interacted to identify and characterize the safety signal of myocarditis and pericarditis after COVID-19 mRNA vaccination. Articles were synthesized from a PubMed search using relevant keywords for articles published on vaccine surveillance systems and myocarditis and pericarditis after COVID-19 vaccination, as well as the authors' collections of relevant publications and grey literature reports. The global experience around the identification and monitoring of myocarditis and pericarditis after COVID-19 mRNA vaccination has provided important lessons for vaccine safety surveillance and highlighted its importance in maintaining public trust in mass vaccination programmes in a pandemic context.

Inactivated Vaccine-Induced SARS-CoV-2 Variant-Specific Immunity in Children

Multiple vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been evaluated in clinical trials. However, trials addressing the immune response in the pediatric population are scarce. The inactivated vaccine CoronaVac has been shown to be safe and immunogenic in a phase 1/2 clinical trial in a pediatric cohort in China. Here, we report interim safety and immunogenicity results of a phase 3 clinical trial for CoronaVac in healthy children and adolescents in Chile. Participants 3 to 17 years old received two doses of CoronaVac in a 4-week interval until 31 December 2021. Local and systemic adverse reactions were registered for volunteers who received one or two doses of CoronaVac. Whole-blood samples were collected from a subgroup of 148 participants for humoral and cellular immunity analyses. The main adverse reaction reported after the first and second doses was pain at the injection site. Four weeks after the second dose, an increase in neutralizing antibody titer was observed in subjects relative to their baseline visit. Similar results were found for activation of specific CD4⁺ T cells. Neutralizing antibodies were identified against the Delta and Omicron variants. However, these titers were lower than those for the D614G strain. Importantly, comparable CD4⁺ T cell responses were detected against these variants of concern. Therefore, CoronaVac is safe and immunogenic in subjects 3 to 17 years old, inducing neutralizing antibody secretion and activating CD4⁺ T cells against SARS-CoV-2 and its variants. (This study has been registered at ClinicalTrials.gov under no. NCT04992260.) IMPORTANCE This work evaluated the immune response induced by two doses of CoronaVac separated by 4 weeks in healthy children and adolescents in Chile. To date, few studies have described the effects of CoronaVac in the pediatric population. Therefore, it is essential to generate knowledge regarding the protection of vaccines in this population. Along these lines, we reported the anti-S humoral response and cellular immune response to several SARS-CoV-2 proteins that have been published and recently studied. Here, we show that a vaccination schedule consisting of two doses separated by 4 weeks induces the secretion of neutralizing antibodies against SARS-CoV-2. Furthermore, CoronaVac induces the activation of CD4⁺ T cells upon stimulation with peptides from the proteome of SARS-CoV-2. These results indicate that, even though the neutralizing antibody response induced by vaccination decreases against the Delta and Omicron variants, the cellular response against these variants is comparable to the response against the ancestral strain D614G, even being significantly higher against Omicron.

An Evaluation of Serological Tests to Determine Postvaccinal Immunity to SARS-CoV-2 by mRNA Vaccines

BACKGROUND

The duration of the protective efficacy of vaccines against SARS-CoV-2 is unknown. Thus, an evaluation of the clinical performance of available tests is required.

OBJECTIVES

To evaluate the clinical performance of LFIA immunoassay compared to ELIA and CLIA immunoassays available in Europe for the detection of IgG antibodies generated by mRNA vaccines against SARS-CoV-2.

METHODS

Two automated immunoassays (the EUROIMMUN anti-SARS-CoV-2 IgG S1 ELISA and the LIAISON de Diasorin anti-SARS-CoV-2 IgG S1/S2 test) and a lateral flow immunoassay (the Livzon LFIA anti-SARS-CoV-2 IgG S test) were tested. We analyzed 300 samples distributed in three groups: 100 subjects aged over 18 years and under 45 years, 100 subjects aged between 45 and 65 years, and 100 subjects aged over 65 years. The samples were collected before vaccination; at 21 days; and then at 1, 2, 3, and 6 months after vaccination. The sensitivity, specificity, positive predictive value, negative predictive value, positive probability quotient, negative probability quotient, and concordance (kappa index) were calculated for each serological test.

RESULTS

The maximum sensitivity values for IgG were 98.7%, 98.1%, and 97.8% for the EUROIMMUN ELISA, Abbott CLIA, and Livzon LFIA tests, respectively, and the maximum specificity values for IgG were 99.4%, 99.9%%, and 98.4% for the ELISA, CLIA, and LFIA tests, respectively, at the third month after vaccination, representing a decrease in the antibody levels after the sixth month. The best agreement was observed between the ELISA and CLIA tests at 100% (k = 1.00). The agreement between the ELIA, CLIA, and LFIA tests was 99% (k = 0.964) at the second and third month after vaccination. Seroconversion was faster and more durable in the younger age groups.

CONCLUSION

Our study examined the equivalent and homogeneous clinical performance for IgG of three immunoassays after vaccination and found LFIA to be the most cost-effective, reliable, and accurate for routine use in population seroconversion and seroprevalence studies.

The BNT162b2 vaccine induces humoral and cellular immune memory to SARS-CoV-2 Wuhan strain and the Omicron variant in children 5 to 11 years of age

SARS-CoV-2 mRNA vaccines prevent severe COVID-19 by generating immune memory, comprising specific antibodies and memory B and T cells. Although children are at low risk of severe COVID-19, the spreading of highly transmissible variants has led to increasing in COVID-19 cases and hospitalizations also in the youngest, but vaccine coverage remains low. Immunogenicity to mRNA vaccines has not been extensively studied in children 5 to 11 years old. In particular, cellular immunity to the wild-type strain (Wuhan) and the cross-reactive response to the Omicron variant of concern has not been investigated. We assessed the humoral and cellular immune response to the SARS-CoV-2 BNT162b2 vaccine in 27 healthy children. We demonstrated that vaccination induced a potent humoral and cellular immune response in all vaccinees. By using spike-specific memory B cells as a measurable imprint of a previous infection, we found that 50% of the children had signs of a past, undiagnosed infection before vaccination. Children with pre-existent immune memory generated significantly increased levels of specific antibodies, and memory T and B cells, directed against not only the wild type virus but also the omicron variant.

COVID-19 vaccination side effects among the child age group: a large cross-sectional online based survey in Saudi Arabia

BACKGROUND

Multiple vaccines have been tested in clinical trials for their efficacy and safety. In Saudi Arabia, Pfizer-BioNTech or Moderna were approved for children, however, previous studies to report their safety profile are limited. This research aims to understand the side effect of children's vaccination against SARS-CoV-2 infection in Saudi Arabia.

METHODS

This was an observational retrospective cross-sectional study was conducted using an online survey in Saudi Arabia from March to May 2022. The inclusion criteria were parents aged 18 years and above who live in Saudi Arabia and have vaccinated their children. The self-reported questionnaire was adopted from published studies to investigate the study objectives Descriptive statistics were used to describe patients' demographic characteristics, continuous data were reported as mean ± S.D., categorical data were reported as percentages (frequencies), and logistic regression was used to identify predictors of persistent post-COVID-19 symptoms.

RESULTS

This study had a total of 4,069 participants. Only 41.9% of the participants reported that their child(ren) had been infected with the coronavirus. 2.00 was the median number of children (IQR: 1.00-4.00). More than half of the study participants (64.2%) reported that a family member had been infected with the coronavirus. Both parents received COVID-19 vaccination, according to most participants (88.7%). Most participants (70.5%) stated that all children who met the vaccination criteria had received the vaccine. Most participants (83.5%) said their child or children had two doses of their vaccine, and about half (50.4%) of those who received the vaccine reported experiencing side effects. In addition, the majority (78.9%) reported that the side effects appeared within one day of receiving the vaccine, and nearly two-thirds (65.7%) reported that the side effects lasted between one and three. A total of 11,831 side effects cases were documented. Pain at the injection site, hyperthermia, and fatigue were the most reported side effects, accounting for 15.3%, 14.1%, and 13.2%, respectively.

CONCLUSION

It appears that the side effects of the COVID-19 vaccine for children are minor, tolerable, and like those described previously in clinical trials. Our data should encourage the public about the safety of receiving the COVID-19 vaccine for children.

Pediatric solid organ transplant recipients demonstrate robust cell-mediated and humoral responses to three doses of mRNA SARS-CoV-2 vaccine

Pediatric solid organ transplant recipients (pSOTR) often demonstrate suboptimal vaccine responses and are not included in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine efficacy trials. This population has shown variable humoral immunity following SARS-CoV-2 vaccination, and no studies have assessed cell-mediated responses after SARS-CoV-2 vaccination in pSOTR. SARS-CoV-2-specific interferon-gamma release assay (IGRA), immunoglobulin G (IgG), and receptor-binding domain (RBD)-angiotensin-converting enzyme 2 (ACE2) blocking antibody (Ab) were measured in pSOTR aged 5-17 years after 2-3 doses of SARS-CoV-2 mRNA vaccine. In all, 33 subjects were included, with 25 tested after the second dose of mRNA vaccine (V2) and 21 tested after the third dose of mRNA vaccine (V3). Of the 19 subjects who had IgG testing after V3, 100.0% (19/19) had a positive IgG response. Of the 17 subjects who had IGRA testing after V3, 94.1% (16/17) had a positive IGRA response. RBD-ACE2 blocking antibody increased significantly from V2 to V3 (p = .007). Subjects <1 year from transplant demonstrated a significantly larger increase in RBD-ACE2 blocking Ab from V2 to V3 than did those >1 year from transplant (p = .05). SARS-CoV-2 vaccination induces humoral and cell-mediated responses in the majority of pSOTR, with improved quantitative humoral response after three doses.

BNT162b2 COVID-19 vaccination uptake, safety, effectiveness and waning in children and young people aged 12-17 years in Scotland

Background

The two-dose BNT162b2 (Pfizer-BioNTech) vaccine has demonstrated high efficacy against COVID-19 disease in clinical trials of children and young people (CYP). Consequently, we investigated the uptake, safety, effectiveness and waning of the protective effect of the BNT162b2 against symptomatic COVID-19 in CYP aged 12-17 years in Scotland.

Methods

The analysis of the vaccine uptake was based on information from the Turas Vaccination Management Tool, inclusive of Mar 1, 2022. Vaccine safety was evaluated using national data on hospital admissions and General Practice (GP) consultations, through a self-controlled case series (SCCS) design, investigating 17 health outcomes of interest. Vaccine effectiveness (VE) against symptomatic COVID-19 disease for Delta and Omicron variants was estimated using a test-negative design (TND) and S-gene status in a prospective cohort study using the Scotland-wide Early Pandemic Evaluation and Enhanced Surveillance of COVID-19 (EAVE II) surveillance platform. The waning of the VE following each dose of BNT162b2 was assessed using a matching process followed by conditional logistic regression.

Findings

Between Aug 6, 2021 and Mar 1, 2022, 75.9% of the 112,609 CYP aged 16-17 years received the first and 49.0% the second COVID-19 vaccine dose. Among 237,681 CYP aged 12-15 years, the uptake was 64.5% and 37.2%, respectively. For 12-17-year-olds, BNT162b2 showed an excellent safety record, with no increase in hospital stays following vaccination for any of the 17 investigated health outcomes. In the 16-17-year-old group, VE against symptomatic COVID-19 during the Delta period was 64.2% (95% confidence interval [CI] 59.2-68.5) at 2-5 weeks after the first dose and 95.6% (77.0-99.1) at 2-5 weeks after the second dose. The respective VEs against symptomatic COVID-19 in the Omicron period were 22.8% (95% CI -6.4-44.0) and 65.5% (95% CI 56.0-73.0). In children aged 12-15 years, VE against symptomatic COVID-19 during the Delta period was 65.4% (95% CI 61.5-68.8) at 2-5 weeks after the first dose, with no observed cases at 2-5 weeks after the second dose. The corresponding VE against symptomatic COVID-19 during the Omicron period were 30.2% (95% CI 18.4-40.3) and 81.2% (95% CI 77.7-84.2). The waning of the protective effect against the symptomatic disease began after five weeks post-first and post-second dose.

Interpretation

During the study period, uptake of BNT162b2 in Scotland has covered more than two-thirds of CYP aged 12-17 years with the first dose and about 40% with the second dose. We found no increased likelihood of admission to hospital with a range of health outcomes in the period after vaccination. Vaccination with both doses was associated with a substantial reduction in the risk of COVID-19 symptomatic disease during both the Delta and Omicron periods, but this protection began to wane after five weeks.

Funding

UK Research and Innovation (Medical Research Council); Research and Innovation Industrial Strategy Challenge Fund; Chief Scientist's Office of the Scottish Government; Health Data Research UK; National Core Studies - Data and Connectivity.

Immune correlates analysis of the ENSEMBLE single Ad26.COV2.S dose vaccine efficacy clinical trial

Measuring immune correlates of disease acquisition and protection in the context of a clinical trial is a prerequisite for improved vaccine design. We analysed binding and neutralizing antibody measurements 4 weeks post vaccination as correlates of risk of moderate to severe-critical COVID-19 through 83 d post vaccination in the phase 3, double-blind placebo-controlled phase of ENSEMBLE, an international randomized efficacy trial of a single dose of Ad26.COV2.S. We also evaluated correlates of protection in the trial cohort. Of the three antibody immune markers we measured, we found most support for 50% inhibitory dilution (ID50) neutralizing antibody titre as a correlate of risk and of protection. The outcome hazard ratio was 0.49 (95% confidence interval 0.29, 0.81; P = 0.006) per 10-fold increase in ID50; vaccine efficacy was 60% (43%, 72%) at non-quantifiable ID50 (<2.7 IU50 ml-1) and increased to 89% (78%, 96%) at ID50 = 96.3 IU50 ml-1. Comparison of the vaccine efficacy by ID50 titre curves for ENSEMBLE-US, the COVE trial of the mRNA-1273 vaccine and the COV002-UK trial of the AZD1222 vaccine supported the ID50 titre as a correlate of protection across trials and vaccine types.

Prevalence of parents' non-intention to vaccinate their children and adolescents against COVID-19: A comparative analysis in Colombia and Peru

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About 9 out of 10 parents in Colombia and Peru intend to vaccinate their children and adolescents against COVID-19.

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Colombia: being vaccinated, 35 to 54 years old, maintaining physical distance, using masks, having economic insecurity, anxiety, and comorbidities increased the intention of vaccinating children and adolescents.

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Peru: being vaccinated, female, maintaining physical distancing, using a mask, having economic insecurity, comorbidities, and have had COVID-19 increased the intention to vaccinate children and adolescents.

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Peru: living in a town, village or rural area was associated with reducing the intention to vaccinate children and adolescents.

We aimed to estimate the prevalence and factors associated with parents’ non-intention to vaccinate their children and adolescents against COVID-19 in Colombia and Peru. We performed a secondary analysis using a database generated by the University of Maryland and Facebook (Facebook, Inc). We Included adult (18 and over) Facebook users residing in LAC who responded to the survey between May 20, and November 5, 2021. We Included sociodemographic characteristics, comorbidities, mental health, economic and food insecurity, compliance with mitigation strategies against COVID-19, and practices related to vaccination against this disease. We estimated crude (cPR) and adjusted (aPR) prevalence ratios with their respective 95 %CI. We analyzed a sample of 44,678 adults from Colombia and 24,302 from Peru. The prevalence of parents' non-intention to vaccinate their children and adolescents against COVID-19 was 7.41 % (n = 3,274) for Colombia and 6.64 % (n = 1,464) for Peru. In Colombia, age above 35 years old, compliance with physical distancing, use of masks, having economic insecurity, anxiety symptoms, having a chronic condition or more comorbidities, and being vaccinated were associated with a higher probability of vaccinating children and adolescents against COVID-19. In Peru, female gender, compliance with physical distancing, use of masks, having economic insecurity, anxiety symptoms, having a chronic condition or more comorbidities, having had COVID-19, and being vaccinated were associated with a higher probability of vaccinating children against COVID-19. Living in a town, a village, or a rural area was associated with a higher prevalence of non-intention to vaccinate children and adolescents against COVID-19. About 9 out of 10 parents in Colombia and Peru intend to vaccinate their children and adolescents against COVID-19. This intention is associated with some factors which are similar between the two countries, as well as other factors and variations among the different regions of each country.

SARS-CoV-2 mRNA-based vaccines in the Aicardi Goutières Syndrome

Aicardi Goutières Syndrome (AGS) is an autoinflammatory disorder resulting in sustained interferon activation through defects in nucleic acid modification and sensing pathways. Thus, mRNA-based vaccination used against SARS-CoV-2, raise disease-specific safety concerns. To assess interferon signaling, we tested mRNA SARS-CoV-2 vaccines in AGS whole blood samples. Interferon activation is measured through quantitation of interferon signaling gene (ISG) expression and is increased in AGS patients. There was no increase in ISG scores from baseline following treatment with the nucleoside modified mRNA formulation compared to an increase with unmodified. A patient-family survey reported that the vaccines were well tolerated. These findings suggest that COVID vaccination using nucleoside-modified forms of mRNA vaccines are unlikely to directly stimulate ISG expression in response to mRNA internalization in AGS tissues. With continued community spread, we recommend vaccination using nucleoside-modified mRNA vaccines in this rare disease group in individuals for whom vaccines were previously well tolerated.

Cardiac Effects of COVID-19 Infection, MIS-C, and the Vaccine in Infants and Children: What Is Known and Future Implications

The cardiac effects of novel coronavirus disease 2019 (COVID-19) infection on the pediatric heart has become an area of particular interest as elevated cardiac enzymes and abnormalities on echocardiogram and electrocardiogram were seen in a portion of children affected by the virus. In this article, we review the cardiac manifestations of acute COVID-19 infection, multisystem inflammatory syndrome in children, and postvaccine myocarditis. The limited research on the effects of COVID-19 on neonates and infants is also reported. KEY POINTS: · Cardiac involvement from MIS-C is much higher than the risk of COVID-19 vaccine-induced myocarditis.. · Neonates and infants have overall been less affected by COVID-19 than adults and older children.. · At this point in time, there is limited research on the cardiac effects of COVID-19 in neonates..

Reasons underlying the intention to vaccinate children aged 5-11 against COVID-19: A cross-sectional study of parents in Israel, November 2021

Vaccination is a key tool to mitigate impacts of the COVID-19 pandemic. In Israel, COVID-19 vaccines became available to adults in December 2020 and to 5-11-year-old children in November 2021. Ahead of the vaccine roll-out in children, we aimed to determine whether surveyed parents intended to vaccinate their children and describe reasons for their intentions. We collected information on parental socio-demographic characteristics, COVID-19 vaccine history, intention to vaccinate their children against COVID-19, and reasons for parental decisions using an anonymous online survey. We identified associations between parental characteristics and plans to vaccinate children using a logistic regression model and described reasons for intentions to vaccinate or not. Parental non-vaccination and having experienced major vaccination side effects were strongly associated with non-intention to vaccinate their children (OR 0.09 and 0.18 respectively, p < .001). Parents who were younger, lived in the socio-economically deprived periphery, and belonged to the Arab population had lower intentions to vaccinate their children. Reasons for non-intention to vaccinate included concerns about vaccine safety and efficacy (53%, 95%CI 50-56) and the belief that COVID-19 is a mild disease (73%, 95%CI 73-79), while a frequent motive for vaccination was the return to normal social and educational life (89%, 95%CI 87-91). Understanding rationales for COVID-19 vaccine rejection or acceptance, as well as parental demographic data, can pave the way for intentional educational campaigns to encourage not only vaccination against COVID-19, but also regular childhood vaccine programming.

Safety of mRNA BNT162b2 COVID-19 (Pfizer-BioNtech) vaccine in children aged 5-11 years: Results from an active pharmacovigilance study in central Italy

This survey investigated on adverse events after vaccination with mRNA BNT162b2 (Comirnaty, Pfizer-BioNTech) vaccine in children aged 5-11 years in central Italy through active surveillance reporting. During December 2021-January 2022, parents of children who undergone vaccination were interviewed using a structured questionnaire. 197 out of 208 contacted parents participated (94.7% response rate), of whom 166 (84.3%) had one child. Of the 229 children, the mean age was 8.9 years, 50.7% were female. 193 (84.3%) had at least one adverse event after the first dose (mean age 9.1 years; 54.4% female), and 146 (73.4%) of 199 after the second (mean age 8.9 years; 54.8% female), which was not administered to 30 children due to previous COVID-19 history. Local symptoms after the first and second dose occurred in 183 (94.8%) and 141 (96.6%) recipients (p = .435), respectively, while systemic reactions in 62 (32.1%) and 34 (23.3%) (p = .074). Mild events were reported by 81.7% and 69.8% children after the first and second dose, followed by moderate (3.9% and 10.6%) and severe (1.3% and 0.5%). After each dose, injection site reactions (79.5% and 68.8%) were the most frequent, followed by headache (13.1%) and lymphadenopathy (8.5%) after the first and second dose, respectively. The adverse events were reported to pediatricians only for 5.7% and 3.9% of children and treated for 17.6% and 15.8%. This is the first report about safety profile through active surveillance of mRNA BNT162b2 among children in Italy, revealing temporary and mild-to-moderate symptoms with no serious events after each vaccine dose.

Correlation between anti-S IgG and neutralizing antibody titers against three live SARS-CoV-2 variants in BNT162b2 vaccine recipients

We analyzed serially collected serum samples from healthy adults who underwent BNT162b2 vaccination to elucidate the association between spike (S)-IgG antibody titers determined by ELISA using the WHO international standard (NIBSC code 20/136) and neutralizing antibody titers against three live SARS-CoV-2 variants. This study included 53 health care workers who received two doses of the BNT162b2 vaccine. S-IgG and nucleocapsid (N)-IgG antibody titers were measured by ELISA. Neutralizing (NT) antibody responses against three variants (Wuhan D614 G: KUH003, Alpha, and Delta) were evaluated before and after the first and second vaccination. N-IgG were not detected in any serum samples. S-IgG antibody titers remarkably increased after two BNT162b2 vaccine doses in all participants. S-IgG antibody titers were strongly correlated with NT titers against three variants of live viruses: KUH003 (r = 0.86), Alpha (r = 0.72), and Delta (r = 0.84). Serum samples from participants after one dose of BNT162b2 neutralized Alpha efficiently (median titer, 113.0), but median NT titers against KUH003 and Delta variants were lower, 57.0 and 28.0, respectively (p < .01). Two doses of the BNT162b2 vaccine elicited a strong immune response in this study. The second dose was required for induction of a strong booster effect. Serum collected from BNT162b2 vaccine recipients contained significantly lower neutralizing activity against Delta than that of against KUH003 (p < .0001) and Alpha (p < .0001). If a new variant emerges, live virus-based NT titers should be examined in serum obtained from vaccine recipients to evaluate vaccine efficacy for protection against infection.

COVID-19 Epidemiology, Immunity, and Vaccine Development in Children: A Review

Although pediatric populations experienced lower COVID-19 severity and mortality than adults, the epidemiology of this disease continues to evolve. COVID-19 clinical manifestations in pediatrics commonly include fever and cough, but may differ from adults and by variant. Serious complications, including MIS-C, rarely occur. Although early data showed a decreased likelihood of COVID-19 transmission from children versus adults, outbreaks and viral shedding studies support pediatric transmission potential. Children may mount more robust initial immune responses to SARS-CoV-2 versus adults. COVID-19 vaccines with available pediatric data include BNT162b2, mRNA-1273, CoronaVac, and BBIBP-CorV. Depending on age group and jurisdiction, BNT162b2 and mRNA-1273 have received full approval or emergency/conditional authorization in the United States and European Union from 6 months of age. Clinical trials have shown BNT162b2 and mRNA-1273 safety and high efficacy in pediatric populations, with demonstrably noninferior immune responses versus young adults. Real-world studies further support BNT162b2 safety and effectiveness against the Delta variant. mRNA vaccination benefits are considered to outweigh risks, including myocarditis; however, pediatric vaccination rates remain relatively low. Given a growing body of clinical trial and real-world data showing vaccine safety and effectiveness, pediatric vaccination should be prioritized as an important strategy to control the pandemic.

Parent Acceptance toward Inactivated COVID-19 Vaccination in Children with Acute Lymphoblastic Leukemia: The Power of Oncologist and Alliance

Objectives: The current study aims to survey the willingness of parents to vaccinate their children, who are childhood acute lymphoblastic leukemia survivors (CALLS), and identify factors associated with vaccine acceptance. Methods: Parents of CALLS on/off treatment, with the general condition of being amendable to vaccination, were recruited for interviews with attending oncologists about COVID-19 vaccination acceptance from July to November 2021 in China. After controlling for socioeconomic factors, the Association of Oncologists’ recommendations and parent−oncologist alliance with acceptance status were investigated. For validation, propensity score-matched (PSM) analysis was used. Results: A total of 424 families were included in the study, with CALLS mean remission age of 5.99 ± 3.40 years. Among them, 91 (21.4%) agreed, 168 (39.6%) hesitated, and 165 (38.9%) parents disagreed with the vaccination. The most common reason that kept parents from vaccinating their children was lack of recommendations from professional personnel (84/165, 50.9%), and massive amounts of internet information (78/175, 44.6%) was the main nonhealthcare resource against vaccination. Logistic regression analysis showed that only the recommendation from the oncologist was associated with parents’ vaccine acceptance (OR = 3.17, 95% CI = 1.93−5.20), as demonstrated by PSM comparison (42 in recommendation group vs. 18 in nonrecommendation group among 114 pairs, p < 0.001). An exploratory analysis revealed that parents with a better patient−oncologist alliance had a significantly higher level of acceptance (65.6% in alliance group vs. 15.6% in nonalliance group among 32 pairs, p < 0.001). Conclusions: Due to a lack of professional recommendation resources and the potential for serious consequences, parents were generally reluctant to vaccinate their CALLS. The recommendation of oncologists, which was influenced by the parent−oncologist alliance, significantly increased acceptance. This study emphasizes the critical role of oncologists in vaccinating cancer survivors and can be used to promote COVID-19 vaccines among vulnerable populations.

SARS-CoV-2 mRNA vaccination elicits robust antibody responses in children

Although children have been largely spared from coronavirus disease 2019 (COVID-19), the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) with increased transmissibility, combined with fluctuating mask mandates and school reopenings, has led to increased infections and disease among children. Thus, there is an urgent need to roll out COVID-19 vaccines to children of all ages. However, whether children respond equivalently to adults to mRNA vaccines and whether dosing will elicit optimal immunity remain unclear. Here, we aimed to deeply profile the vaccine-induced humoral immune response in 6- to 11-year-old children receiving either a pediatric (50 μg) or adult (100 μg) dose of the mRNA-1273 vaccine and to compare these responses to vaccinated adults, infected children, and children who experienced multisystem inflammatory syndrome in children (MIS-C). Children elicited an IgG-dominant vaccine-induced immune response, surpassing adults at a matched 100-μg dose but more variable immunity at a 50-μg dose. Irrespective of titer, children generated antibodies with enhanced Fc receptor binding capacity. Moreover, like adults, children generated cross-VOC humoral immunity, marked by a decline of omicron-specific receptor binding domain, but robustly preserved omicron spike protein binding. Fc receptor binding capabilities were also preserved in a dose-dependent manner. These data indicate that both the 50- and 100-μg doses of mRNA vaccination in children elicit robust cross-VOC antibody responses and that 100-μg doses in children result in highly preserved omicron-specific functional humoral immunity.

Real-World Immunogenicity and Reactogenicity of Two Doses of Pfizer-BioNTech COVID-19 Vaccination in Children Aged 5-11 Years

There are limited data concerning the immunogenicity and reactogenicity of COVID-19 vaccines in children. A total of 110 children, 5-11 years old were vaccinated with two doses (with a 3-week interval between doses) of the Pfizer-BioNTech COVID-19 vaccine and were followed for 21, 90, and 180 days after vaccination for immunogenicity, adverse events, and breakthrough infections. Ninety days after the first vaccine dose, the GeoMean (CI 95%) of IgG ascended to 1291.0 BAU (929.6-1790.2) for uninfected children and 1670.0 BAU (1131.0-2466.0) for Infected children. One hundred and eighty days after receiving the first dose of the vaccine, the titers decreased to 535.5 BAU (288.4-993.6) for the uninfected children, while only a small decline was detected among infected children-1479.0 (878.2-2490.0). The neutralizing antibodies titer almost did not change over time in the uninfected children, and even elevated for the infected children. Of the 110 vaccinated children, 75.5% were infected, with only mild COVID-19 infection symptoms. Child vaccination was found to be safe, with mild, mostly local, and of short duration, reported AEs. No serious adverse events (SAEs) were reported after vaccination. The durability of two doses of vaccine in children is longer, thus a booster may not be needed as early as in adults.

Covid-19 Vaccine Protection among Children and Adolescents in Qatar

BACKGROUND

The BNT162b2 vaccine against coronavirus disease 2019 (Covid-19) has been authorized for use in children 5 to 11 years of age and adolescents 12 to 17 years of age but in different antigen doses.

METHODS

We assessed the real-world effectiveness of the BNT162b2 vaccine against infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among children and adolescents in Qatar. To compare the incidence of SARS-CoV-2 infection in the national cohort of vaccinated participants with the incidence in the national cohort of unvaccinated participants, we conducted three matched, retrospective, target-trial, cohort studies - one assessing data obtained from children 5 to 11 years of age after the B.1.1.529 (omicron) variant became prevalent and two assessing data from adolescents 12 to 17 years of age before the emergence of the omicron variant (pre-omicron study) and after the omicron variant became prevalent. Associations were estimated with the use of Cox proportional-hazards regression models.

RESULTS

Among children, the overall effectiveness of the 10-μg primary vaccine series against infection with the omicron variant was 25.7% (95% confidence interval [CI], 10.0 to 38.6). Effectiveness was highest (49.6%; 95% CI, 28.5 to 64.5) right after receipt of the second dose but waned rapidly thereafter and was negligible after 3 months. Effectiveness was 46.3% (95% CI, 21.5 to 63.3) among children 5 to 7 years of age and 16.6% (95% CI, -4.2 to 33.2) among those 8 to 11 years of age. Among adolescents, the overall effectiveness of the 30-μg primary vaccine series against infection with the omicron variant was 30.6% (95% CI, 26.9 to 34.1), but many adolescents had been vaccinated months earlier. Effectiveness waned over time since receipt of the second dose. Effectiveness was 35.6% (95% CI, 31.2 to 39.6) among adolescents 12 to 14 years of age and 20.9% (95% CI, 13.8 to 27.4) among those 15 to 17 years of age. In the pre-omicron study, the overall effectiveness of the 30-μg primary vaccine series against SARS-CoV-2 infection among adolescents was 87.6% (95% CI, 84.0 to 90.4) and waned relatively slowly after receipt of the second dose.

CONCLUSIONS

Vaccination in children was associated with modest, rapidly waning protection against omicron infection. Vaccination in adolescents was associated with stronger, more durable protection, perhaps because of the larger antigen dose. (Funded by Weill Cornell Medicine-Qatar and others.).

Humoral and cellular response to the COVID-19 vaccine in immunocompromised children

BACKGROUND

A suboptimal response to the 2-dose COVID-19 vaccine series in the immunocompromised population prompted recommendations for a 3rd primary dose. We aimed to determine the humoral and cellular immune response to the 3rd COVID-19 vaccine in immunocompromised children.

METHODS

Prospective cohort study of immunocompromised participants, 5-21 years old, who received 2 prior doses of an mRNA COVID-19 vaccine. Humoral and CD4/CD8 T-cell responses were measured to SARS-CoV-2 spike antigens prior to receiving the 3rd vaccine dose and 3-4 weeks after the 3rd dose was given.

RESULTS

Of the 37 participants, approximately half were solid organ transplant recipients. The majority (86.5%) had a detectable humoral response after the 2nd and 3rd vaccine doses, with a significant increase in antibody levels after the 3rd dose. Positive T-cell responses increased from being present in 86.5% to 100% of the cohort after the 3rd dose.

CONCLUSIONS

Most immunocompromised children mount a humoral and cellular immune response to the 2-dose COVID-19 vaccine series, which is significantly augmented after receiving the 3rd vaccine dose. This supports the utility of the 3rd vaccine dose and the rationale for ongoing emphasis for vaccination against COVID-19 in this population.

IMPACT

Most immunocompromised children mount a humoral and cellular immune response to the 2-dose COVID-19 vaccine series, which is significantly augmented after receiving the 3rd vaccine dose. This is the first prospective cohort study to analyze both the humoral and T-cell immune response to the 3rd COVID-19 primary vaccine dose in children who are immunocompromised. The results of this study support the utility of the 3rd vaccine dose and the rationale for ongoing emphasis for vaccination against COVID-19 in the immunosuppressed pediatric population.

Do we need to vaccinate every child against COVID-19: What evidence suggests-A systematic review of opinions

It is still debatable whether all children should receive the COVID-19 vaccine. The comparatively mild cases and low risk of COVID-19 in children compared to adults, as well as the lack of clarity on the relative effects of the disease and vaccine, indicate that the risk-benefit ratio of vaccination in children is more nuanced. To consider and highlight the complexity of policy decisions regarding COVID-19 vaccination in children, we outlined the points regarding for and against vaccination of children against COVID-19 in this systemic review. Using Medical Search Headings (MeSH) terms and keywords, we searched PubMed, PubMed Central, Scopus, and Google Scholar. The primary search term was COVID-19 vaccination (all synonyms), factors (all synonyms), and among children (all synonyms). A total of 367 articles were searched. Finally, 64 articles met the inclusion criteria and were included in the review. The major theme/tone of 28 (43.75%) articles was in favor of children's COVID vaccination, and they were highlighting the positive factors, whereas the major theme/tone of 20 (31.25%) articles was against it. Approximately 16 (25.0%) articles were in a neutral position. Major factors highlighted by articles in favor of childhood COVID vaccination were as follows: the increasing rate of disease burden (29 articles), prevention of interruption of academic activities of children or school reopening (24 articles), and a role in defense against COVID infection (21 articles). Major factors against childhood vaccination were as follows: mild infection among children (27 articles), ethical concerns and legal problems regarding the consent of minors (17 articles), and vaccine hesitancy among parents for childhood vaccination (11 articles). Whereas, factors of uncertainty were the role in the reduction of community transmission (19 articles), protection against MIS-C (10 articles), and defense against long COVID (7 articles). Considering all the factors of COVID-19 disease progression among children, a cautious approach will be essential before proceeding with COVID-19 vaccination in children.

Effectiveness of the BNT162b2 (Pfizer-BioNTech) Vaccine in Children and Adolescents: A Systematic Review and Meta-Analysis

Efforts to control the COVID-19 pandemic have expanded to the vaccination of children and adolescents. This systematic review assesses the utility of the BNT162b2 (Pfizer-BioNTech) vaccine in children and adolescents aged 5-18 years, considering its effectiveness against COVID infection, hospital and intensive care admission and duration of effectiveness after vaccination. Six databases were searched following the PRISMA guidelines. Pooled estimates and 95% confidence intervals (CIs) were calculated using meta-analysis. Fifteen studies were included in the systematic review, while 12 studies were included in the meta-analysis. Evidence suggests that the two-dose vaccination regime provided high effectiveness of 92% (95% CI, 86-96) against COVID infection. Vaccination also conferred high protection against hospitalisation (91%) and intensive care admission (85%). The vaccine was highly protective against the Delta variant of the virus, but showed a lower protection against the Omicron variant. Most adverse effects were transient and mild, commonly including pain at the injection site, fatigue and headache. Current findings are suggestive of waning immunity over time; however, further research is needed to investigate the relevance of booster doses in this age group. In summary, the Pfizer-BioNTech BNT162b2 vaccine demonstrated high levels of protection against COVID-19 infection and its complications while maintaining an adequate safety profile in children and adolescents.

Evaluation of mRNA-1273 Vaccine in Children 6 Months to 5 Years of Age

BACKGROUND

The safety, reactogenicity, immunogenicity, and efficacy of the mRNA-1273 coronavirus disease 2019 (Covid-19) vaccine in young children are unknown.

METHODS

Part 1 of this ongoing phase 2-3 trial was open label for dose selection; part 2 was an observer-blinded, placebo-controlled evaluation of the selected dose. In part 2, we randomly assigned young children (6 months to 5 years of age) in a 3:1 ratio to receive two 25-μg injections of mRNA-1273 or placebo, administered 28 days apart. The primary objectives were to evaluate the safety and reactogenicity of the vaccine and to determine whether the immune response in these children was noninferior to that in young adults (18 to 25 years of age) in a related phase 3 trial. Secondary objectives were to determine the incidences of Covid-19 and severe acute respiratory syndrome coronavirus 2 infection after administration of mRNA-1273 or placebo.

RESULTS

On the basis of safety and immunogenicity results in part 1 of the trial, the 25-μg dose was evaluated in part 2. In part 2, 3040 children 2 to 5 years of age and 1762 children 6 to 23 months of age were randomly assigned to receive two 25-μg injections of mRNA-1273; 1008 children 2 to 5 years of age and 593 children 6 to 23 months of age were randomly assigned to receive placebo. The median duration of follow-up after the second injection was 71 days in the 2-to-5-year-old cohort and 68 days in the 6-to-23-month-old cohort. Adverse events were mainly low-grade and transient, and no new safety concerns were identified. At day 57, neutralizing antibody geometric mean concentrations were 1410 (95% confidence interval [CI], 1272 to 1563) among 2-to-5-year-olds and 1781 (95% CI, 1616 to 1962) among 6-to-23-month-olds, as compared with 1391 (95% CI, 1263 to 1531) among young adults, who had received 100-μg injections of mRNA-1273, findings that met the noninferiority criteria for immune responses for both age cohorts. The estimated vaccine efficacy against Covid-19 was 36.8% (95% CI, 12.5 to 54.0) among 2-to-5-year-olds and 50.6% (95% CI, 21.4 to 68.6) among 6-to-23-month-olds, at a time when B.1.1.529 (omicron) was the predominant circulating variant.

CONCLUSIONS

Two 25-μg doses of the mRNA-1273 vaccine were found to be safe in children 6 months to 5 years of age and elicited immune responses that were noninferior to those in young adults. (Funded by the Biomedical Advanced Research and Development Authority and National Institute of Allergy and Infectious Diseases; KidCOVE ClinicalTrials.gov number, NCT04796896.).

Management of patients with allergic diseases in the era of COVID-19

In the early days of the coronavirus disease 2019 (COVID-19) pandemic, allergic diseases, especially asthma, were considered to be risk factors for severe COVID-19 infection, hospitalization, and death. These concerns stemmed from the idea that individuals with allergic diseases are generally more susceptible to respiratory virus infections, which are major causes of exacerbation of allergic diseases. However, epidemiologic data with mechanistic studies showed that the associations between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and clinical outcomes of allergic diseases are complex and affected by diverse factors such as allergic disease severity, phenotypes, and control status with current medications. In addition, children generally have less severe clinical outcomes of COVID-19 than those of adults, which complicates the association between allergic diseases and COVID-19-related outcomes among them. The present review summarizes the potential association between allergic diseases and COVID-19-related outcomes and discusses the factors requiring consideration. The findings viewed herein will aid the management of allergic diseases in patients with SARS-CoV-2 infection and the establishment of medical polices for managing patients with allergic diseases.

Differential Infectivity of Original and Delta Variants of SARS-CoV-2 in Children Compared to Adults

Although children of all ages are susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, they have not been implicated as major drivers of transmission thus far. However, it is still unknown if this finding holds true with new variants of concern (VOC), such as Delta (B.1.617.2). This study aimed to examine differences in both viral RNA (as measured by cycle threshold [CT]) and viable-virus levels from children infected with Delta and those infected with original variants (OV). Furthermore, we aimed to compare the pediatric population infection trends to those in adults. We obtained 690 SARS-CoV-2 RT-PCR positive nasopharyngeal swabs from across Manitoba, Canada, which were further screened for mutations characteristic of VOC. Aliquots of sample were then provided for TCID50 (50% tissue culture infective dose) assays to determine infectious titers. Using a variety of statistical analyses we compared CT and infectivity of VOC in different age demographics. Comparing 122 Delta- to 175 OV-positive nasopharyngeal swab samples from children, we found that those infected with Delta are 2.7 times more likely to produce viable SARS-CoV-2 with higher titers (in TCID50 per milliliter), regardless of viral RNA levels. Moreover, comparing the pediatric samples to 130 OV- and 263 Delta-positive samples from adults, we found only that the Delta pediatric culture-positive samples had titers (TCID50 per milliliter) similar to those of culture-positive adult samples. IMPORTANCE These important findings show that children may play a larger role in viral transmission of Delta than for previously circulating SARS-CoV-2 variants. Additionally, they may suggest a mechanism for why Delta has evolved to be the predominant circulating variant.

Immunogenicity, efficacy, and safety of SARS-CoV-2 vaccine dose fractionation: a systematic review and meta-analysis

BACKGROUND

Dose fractionation of a coronavirus disease 2019 (COVID-19) vaccine could effectively accelerate global vaccine coverage, while supporting evidence of efficacy, immunogenicity, and safety are unavailable, especially with emerging variants.

METHODS

We systematically reviewed clinical trials that reported dose-finding results and estimated the dose-response relationship of neutralizing antibodies (nAbs) of COVID-19 vaccines using a generalized additive model. We predicted the vaccine efficacy against both ancestral and variants, using previously reported correlates of protection and cross-reactivity. We also reviewed and compared seroconversion to nAbs, T cell responses, and safety profiles between fractional and standard dose groups.

RESULTS

We found that dose fractionation of mRNA and protein subunit vaccines could induce SARS-CoV-2-specific nAbs and T cells that confer a reasonable level of protection (i.e., vaccine efficacy > 50%) against ancestral strains and variants up to Omicron. Safety profiles of fractional doses were non-inferior to the standard dose.

CONCLUSIONS

Dose fractionation of mRNA and protein subunit vaccines may be safe and effective, which would also vary depending on the characteristics of emerging variants and updated vaccine formulations.

Safety after BBIBP-CorV (Sinopharm) COVID-19 Vaccine in Adolescents Aged 10-17 Years in Thailand

Coronavirus disease 2019 affected child health and impacted learning because of the resulting onsite school closures. This prospective cohort study included children aged 10-17 who received two 4 µg doses of BBIBP-CorV administered intramuscularly 21-28 days apart. To assess vaccine safety, 36,808 participants were then followed with paper- and web-based online questionnaire surveys that captured local and systemic reactogenicities following vaccine administration on days 1, 7, and 30. Among participants, 76% (27,880) reported reactogenicity within the first 24 h and 7 days following the first dose. Half (51.41%) of participants experienced pain at the injection site; the majority of cases were mild in severity. Injection site tenderness (37.93%) was another common local reaction. Fatigue (37.89%), myalgia (33.56%), and headache (26.76%) were the most common systemic reactions. On days 2-7 after the first dose, 25.85% of participants experienced adverse reactions. Following the second dose, reactogenicity was 7.6% and 1.09% within 24 h and between days 2-7. The majority of reactions were of mild to moderate severity. We report that two doses of the BBIBP-CorV caused mild to moderate side effects in adolescents in Thailand. The findings confirm the vaccine's safety profile in this age group.

COVID-19 vaccine update: vaccine effectiveness, SARS-CoV-2 variants, boosters, adverse effects, and immune correlates of protection

Coronavirus Disease 2019 (COVID-19) has been the most severe public health challenge in this century. Two years after its emergence, the rapid development and deployment of effective COVID-19 vaccines have successfully controlled this pandemic and greatly reduced the risk of severe illness and death associated with COVID-19. However, due to its ability to rapidly evolve, the SARS-CoV-2 virus may never be eradicated, and there are many important new topics to work on if we need to live with this virus for a long time. To this end, we hope to provide essential knowledge for researchers who work on the improvement of future COVID-19 vaccines. In this review, we provided an up-to-date summary for current COVID-19 vaccines, discussed the biological basis and clinical impact of SARS-CoV-2 variants and subvariants, and analyzed the effectiveness of various vaccine booster regimens against different SARS-CoV-2 strains. Additionally, we reviewed potential mechanisms of vaccine-induced severe adverse events, summarized current studies regarding immune correlates of protection, and finally, discussed the development of next-generation vaccines.

Comparative Safety of the BNT162b2 Messenger RNA COVID-19 Vaccine vs Other Approved Vaccines in Children Younger Than 5 Years

IMPORTANCE

SARS-CoV-2 vaccines are authorized for use in most age groups. The safety of SARS-CoV-2 vaccines is unknown in children younger than 5 years.

OBJECTIVE

To retrospectively evaluate the safety of the BNT162b2 vaccine used off-label in children younger than 5 years compared with the safety of non-SARS-CoV-2 vaccines in the same sample.

DESIGN, SETTING, AND PARTICIPANTS

This investigator-initiated retrospective cohort study included parents or caregivers who registered children for SARS-CoV-2 vaccination in outpatient care facilities in Germany. The study was performed as an authenticated online survey. A total of 19 000 email addresses were contacted from vaccination registration databases between April 14 and May 9, 2022. Inclusion criteria were child age younger than 5 years at the first BNT162b2 vaccination and use of a correct authentication code to prove invitation.

EXPOSURES

Off-label BNT162b2 vaccination and on-label non-SARS-CoV-2 vaccinations.

MAIN OUTCOMES AND MEASURES

Reported short-term safety data of 1 to 3 doses of 3 to 10 μg BNT162b2 in children from birth to younger than 60 months are presented. Coprimary outcomes were the frequencies of 11 categories of symptoms after vaccination with bivariate analyses and regression models adjusting for age, sex, weight, and height.

RESULTS

The study included 7806 children (median age, 3 years [IQR, 2-4 years]; 3824 [49.0%] female) who were followed up of for a mean (SD) of 91.4 (38.8) days since first BNT162b2 vaccination (survey response rate, 41.1%). A 10-μg dosage was more frequently associated with local injection-site symptoms compared with lower dosages. In the active-comparator analysis, the probability of any symptoms (odds ratio [OR], 1.62; 95% CI, 1.43-1.84), local symptoms (OR, 1.68; 95% CI, 1.38-2.05), musculoskeletal symptoms (OR, 2.55; 95% CI, 1.32-4.94), dermatologic symptoms (OR, 2.18; 95% CI, 10.7-4.45), or otolaryngologic symptoms (OR, 6.37; 95% CI, 1.50-27.09) were modestly elevated after BNT162b2 compared with non-SARS-CoV-2 vaccines, whereas the probabilities of general symptoms (OR, 0.77; 95% CI, 0.63-0.95) and fever (OR, 0.42; 95% CI, 0.32-0.55) were lower after BNT162b2. Symptoms requiring hospitalization (n = 10) were reported only at BNT162b2 dosages above 3 μg.

CONCLUSIONS AND RELEVANCE

In this cohort study, the symptoms reported after BNT162b2 administration were comparable overall to those for on-label non-SARS-CoV-2 vaccines in this cohort of children younger than 5 years. The present data may be used together with prospective licensure studies of BNT162b2 efficacy and safety and could help guide expert recommendations about BNT162b2 vaccinations in this age group.

The next frontier in vaccine design: blending immune correlates of protection into rational vaccine design

Despite the extraordinary speed and success in SARS-Cov-2 vaccine development, the emergence of variants of concern perplexed the vaccine development community. Neutralizing antibodies waned antibodies waned and were evaded by viral variants, despite the preservation of protection against severe disease and death across vaccinated populations. Similar to other vaccine design efforts, the lack of mechanistic correlates of immunity against Coronavirus Disease 2019, raised questions related to the need for vaccine redesign and boosting. Hence, our limited understanding of mechanistic correlates of immunity - across pathogens - remains a major obstacle in vaccine development. The identification and incorporation of mechanistic correlates of immunity are key to the accelerated design of highly impactful globally relevant vaccines. Systems-biology tools can be applied strategically to define a complete understanding of mechanistic correlates of immunity. Embedding immunological dissection and target immune profile identification, beyond canonical antibody binding and neutralization, may accelerate the design and success of durable protective vaccines.

Systemic and Mucosal Humoral Immune Response Induced by Three Doses of the BNT162b2 SARS-CoV-2 mRNA Vaccines

BNT162b2 (BioNTech/Pfizer) was the first SARS-CoV-2 mRNA vaccine approved by the European Medicines Agency. We monitored the long-term humoral responses of healthcare workers (HCWs) who received three vaccine doses. A total of 59 healthcare workers were studied: 47 were never SARS-CoV-2-infected (naïve-HCWs), and 12 (infected-HCWs) recovered from COVID-19 before the first vaccine. Serum and saliva were collected at baseline (before the first dose), just before the second dose, 1, 3, 6, and 9 months after the second dose, and 10 days after the third vaccine. SARS-CoV-2-specific IgG and IgA were evaluated in serum and saliva, respectively, and the presence of neutralizing antibodies (NAb) was analyzed in serum. SARS-CoV-2-specific IgG peaked one month after the second vaccine in naïve-HCWs but right before this timepoint in infected-HCWs. IgG titers significantly decreased during follow-up and at month 9 were still detectable in 50% of naïve-HCWs and 90% of infected-HCWs. NAb were significantly decreased 6 months after the second vaccine in naïve-HCWs and 9 months after this dose in infected-HCWs. Salivary SARS-CoV-2-specific IgA titers were significantly higher in infected-HCWs and were undetectable 9 months after the second vaccine in 43% of the naïve-HCWs alone. The third vaccine greatly increased humoral IgG and mucosal IgA in both groups. Two BNT162b2 doses induced strong systemic and humoral immune responses; to note, these responses weakened over time, although they are more prolonged in individuals who had recovered from COVID-19. The third vaccine dose quickly boosts systemic and mucosal humoral responses.

Uncommon Side Effects of COVID-19 Vaccination in the Pediatric Population

Introduction

The rapid development of vaccines followed the Coronavirus disease 2019 (COVID-19) pandemic. There is still significant vaccine hesitancy, especially among parents. Large-scale pediatric population-based studies or reviews about vaccine side effects are limited.

Data sources and methods

The Centers for Disease Control and Prevention (CDC) recommends recipients or their providers notify possible adverse events to the Vaccine Adverse Event Reporting System (VAERS). We evaluated Delaware state data from the VAERS system for the pediatric age group.

Results

A total of 111 reports were reviewed, with summaries of the reported key side effects discussed, including seizures, myocarditis, stroke, multisystem inflammatory syndrome in children (MIS-C), chest pain, hematuria, menstrual disorder, appendicitis, behavioral and otological side effects, etc.

Conclusions

We noted the approximate prevalence of reported adverse events to be <0.2%. Further studies with larger sample sizes or those focused on each key side effect are needed to evaluate these side effects in detail. An open discussion about the possible side effects and reinforcing the individual, family, and community benefits are key to promoting COVID-19 vaccine acceptance.

OX40 agonist stimulation increases and sustains humoral and cell-mediated responses to SARS-CoV-2 protein and saRNA vaccines

To prevent SARS-CoV-2 infections and generate long-lasting immunity, vaccines need to generate strong viral-specific B and T cell responses. Previous results from our lab and others have shown that immunizations in the presence of an OX40 agonist antibody lead to higher antibody titers and increased numbers of long-lived antigen-specific CD4 and CD8 T cells. Using a similar strategy, we explored the effect of OX40 co-stimulation in a prime and boost vaccination scheme using an adjuvanted SARS-CoV-2 spike protein vaccine in C57BL/6 mice. Our results show that OX40 engagement during vaccination significantly increases long-lived antibody responses to the spike protein. In addition, after immunization spike protein-specific proliferation was greatly increased for both CD4 and CD8 T cells, with enhanced, spike-specific secretion of IFN-γ and IL-2. Booster (3^rd injection) immunizations combined with an OX40 agonist (7 months post-prime) further increased vaccine-specific antibody and T cell responses. Initial experiments assessing a self-amplifying mRNA (saRNA) vaccine encoding the spike protein antigen show a robust antigen-specific CD8 T cell response. The saRNA spike-specific CD8 T cells express high levels of GrzmB, IFN-γ and TNF-α which was not observed with protein immunization and this response was further increased by the OX40 agonist. Similar to protein immunizations the OX40 agonist also increased vaccine-specific CD4 T cell responses. In summary, this study compares and contrasts the effects and benefits of both protein and saRNA vaccination and the extent to which an OX40 agonist enhances and sustains the immune response against the SARS-CoV-2 spike protein.

Intrinsic Kidney Pathology in Children and Adolescents Following COVID-19 Vaccination: A Systematic Review

Global COVID-19 vaccination programs for children and adolescents have been developed with international clinical trial data confirming COVID-19 mRNA vaccine safety and efficacy for the pediatric population. The impact of COVID-19 vaccination in the kidneys is thought to be explained by a complex immune-mediated relationship between the two, although the pathophysiological mechanisms of how COVID-19 vaccination potentially induces kidney pathology are not presently well known. Whilst intrinsic kidney pathologies following COVID-19 vaccination have been reported in adults, such cases are only being recently reported with greater frequency in children and adolescents. Conforming to the PRISMA checklist, we conducted a systematic review of the current literature to provide an overview on the range of intrinsic kidney pathologies that have been reported following COVID-19 vaccination in children and adolescents. All English language research articles published on or before 30 June 2022 reporting new-onset or relapsed intrinsic kidney pathology in children or adolescents (≤18 years) following COVID-19 vaccination were selected for qualitative analysis. Out of 18 cases from the 13 published articles selected, there were 10 cases of IgA nephropathy (1 case of rapidly progressive glomerulonephritis requiring acute hemodialysis), 5 cases of minimal change disease (MCD), 1 case of concurrent MCD/tubulointerstitial nephritis (TIN) and 2 cases of TIN. There is no indication currently to avoid vaccination, unless specific circumstances exist, as the benefits of COVID-19 vaccination far outweigh its risks. Concluding the findings from our systematic review based on preliminary evidence, potential adverse effects to the kidney from COVID-19 vaccination affects a small number of children and adolescents among the many who have been vaccinated. There remains good reason at present to support vaccination of children and adolescents with a greater morbidity status, such as those living with preexisting chronic kidney disease. Close observation of all children and adolescents receiving COVID-19 vaccination is recommended, particularly in those with preceding intrinsic kidney pathology to identify risks of relapsed disease.

Safety of and antibody response to the BNT162b2 COVID-19 vaccine in adolescents and young adults with underlying disease

BACKGROUND

Data are limited regarding the safety of and antibody response to the BNT162b2 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger ribonucleic acid vaccine in adolescents and young adults with underlying disease.

METHODS

This prospective observational study enrolled patients age 12-25 years with chronic underlying disease who received 2 doses of BNT162b2. A 18-item questionnaire was used to assess adverse events within 7 days post-vaccination, and data regarding severe adverse events were collected from electronic medical records. An antibody titer for the receptor-binding domain of the spike protein in SARS-CoV-2 was used to assess antibody response after the second vaccine dose.

RESULTS

Study participants were 429 patients (241 [56.2%] age 12-15 years; 188 [43.8%] age 16-25 years). The most common underlying diseases were genetic or chromosomal abnormalities and/or congenital anomalies, followed by endocrine or metabolic diseases; 32% of participants were immunocompromised. Severe adverse events were observed after the second dose in 1 (0.4%) patient age 12-15 years and in 2 (1.1%) patients age 16-25 years; all patients recovered. Seropositivity after the second vaccine dose was 99.0%. The geometric mean antibody titer was higher in patients age 12-15 years versus 16-25 years (1603.3 [1321.8-1944.7] U/mL vs. 949.4 [744.2-1211.0] U/mL). Compared with immunocompetent patients, immunocompromised patients had a lower antibody titer (2106.8 [1917.5-2314.7] U/mL vs. 467.9 [324.4-674.8] U/mL).

CONCLUSIONS

Vaccination with BNT162b2 was acceptably safe and immunogenic for adolescents and young adults with underlying disease.

Answers to common questions about COVID-19 vaccines in children with cancer

BACKGROUND

The SARS-CoV-2 outbreak in 2020 evolved into a global pandemic, and COVID-19 vaccines became rapidly available, including for pediatric patients. However, questions emerged that challenged vaccine acceptance and use. We aimed to answer these questions and give recommendations applicable for use in pediatric patients with cancer by healthcare professionals and the public.

METHODS

A 12-member global COVID-19 Vaccine in Pediatric Oncology Working Group made up of physicians and nurses from all world regions met weekly from March to July 2021. We used a modified Delphi method to select the top questions. The Working Group, in four-member subgroups, answered assigned questions by providing brief recommendations, followed by a discussion of the rationale for each answer. All Working Group members voted on each recommendation using a scale of 1 to 10, 10 being complete agreement. A "pass" recommendation corresponded to an agreement ≥7.5.

RESULTS

We selected 15 questions from 173 suggested questions. Based on existing published information, we generated answers for each question as recommendations. The overall average agreement for the 24 recommendations was 9.5 (95% CI 9.4-9.6).

CONCLUSION

Top COVID-19 vaccine-related questions could be answered using available information. Reports on COVID-19 vaccination and related topics have been published at record speed, aided by available technology and the priority imposed by the pandemic; however, all efforts were made to incorporate emerging information throughout our project. Recommendations will be periodically updated on a dedicated website.

Loss of Pfizer (BNT162b2) Vaccine-Induced Antibody Responses against the SARS-CoV-2 Omicron Variant in Adolescents and Adults

Emerging variants, especially the recent Omicron variant, and gaps in vaccine coverage threaten mRNA vaccine mediated protection against SARS-CoV-2. While children have been relatively spared by the ongoing pandemic, increasing case numbers and hospitalizations are now evident among children. Thus, it is essential to better understand the magnitude and breadth of vaccine-induced immunity in children against circulating viral variant of concerns (VOCs). Here, we compared the magnitude and breadth of humoral immune responses in adolescents and adults 1 month after the two-dose Pfizer (BNT162b2) vaccination. We found that adolescents (aged 11 to 16) demonstrated more robust binding antibody and neutralization responses against the wild-type SARS-CoV-2 virus spike protein contained in the vaccine compared to adults (aged 27 to 55). The quality of the antibody responses against VOCs in adolescents were very similar to adults, with modest changes in binding and neutralization of Beta, Gamma, and Delta variants. In comparison, a significant reduction of binding titers and a striking lack of neutralization was observed against the newly emerging Omicron variant for both adolescents and adults. Overall, our data show that a two-dose BNT162b2 vaccine series may be insufficient to protect against the Omicron variant. IMPORTANCE While plasma binding and neutralizing antibody responses have been reported for cohorts of infected and vaccinated adults, much less is known about the vaccine-induced antibody responses to variants including Omicron in children. This illustrates the need to characterize vaccine efficacy in key vulnerable populations. A third (booster) dose of BNTb162b was approved for children 12 to 15 years of age by the Food and Drug Administration (FDA) on January 1, 2022, and pediatric clinical trials are under way to evaluate the safety, immunogenicity, and effectiveness of a third dose in younger children. Similarly, variant-specific booster doses and pan-coronavirus vaccines are areas of active research. Our data show adolescents mounted stronger humoral immune responses after vaccination than adults. It also highlights the need for future studies of antibody durability in adolescents and children as well as the need for future studies of booster vaccination and their efficacy against the Omicron variant.

SARS-CoV-2 infection in pediatric population before and during the Delta (B.1.617.2) and Omicron (B.1.1.529) variants era

BACKGROUND

COVID-19, the coronavirus disease that emerged in December 2019, caused drastic damage worldwide. At the beginning of the pandemic, available data suggested that the infection occurs more frequently in adults than in infants. In this review, we aim to provide an overview of SARS-CoV-2 infection in children before and after B.1.617.2 Delta and B.1.1.529 Omicron variants emergence in terms of prevalence, transmission dynamics, clinical manifestations, complications and risk factors.

METHODS

Our method is based on the literature search on PubMed, Science Direct and Google Scholar. From January 2020 to July 2022, a total of 229 references, relevant for the purpose of this review, were considered.

RESULTS

The incidence of SARS-CoV-2 infection in infants was underestimated. Up to the first half of May, most of the infected children presented asymptomatic or mild manifestations. The prevalence of COVID-19 varied from country to another: the highest was reported in the United States (22.5%). COVID-19 can progress and become more severe, especially with the presence of underlying health conditions. It can also progress into Kawasaki or Multisystem Inflammatory Syndrome (MIS) manifestations, as a consequence of exacerbating immune response. With the emergence of the B.1.617.2 Delta and B.1.1.529 Omicron variants, it seems that these variants affect a large proportion of the younger population with the appearance of clinical manifestations similar to those presented by adults with important hospitalization rates.

CONCLUSION

The pediatric population constitutes a vulnerable group that requires particular attention, especially with the emergence of more virulent variants. The increase of symptomatic SARS-CoV-2 infection and hospitalization rate among children highlights the need to extend vaccination to the pediatric population.

Changes in Parents' COVID-19 Vaccine Hesitancy for Children Aged 3-17 Years before and after the Rollout of the National Childhood COVID-19 Vaccination Program in China: Repeated Cross-Sectional Surveys

China started to implement COVID-19 vaccination programs for children in July 2021. This study investigated the changes in parents’ COVID-19 vaccine hesitancy for children before and after the vaccination program rollout. Repeated cross-sectional online surveys among full-time adult factory workers were conducted in Shenzhen, China. This analysis was based on 844 (first round) and 1213 parents (second round) who had at least one child aged 3−17 years. The prevalence of vaccine hesitancy for children aged 3−11 years dropped from 25.9% (first round) to 17.4% (second round), while such a prevalence for children aged 12−17 years dropped from 26.0% (first round) to 3.5% (second round) (p < 0.001). Positive attitudes, a perceived subjective norm, and perceived behavioral control related to children’s COVID-19 vaccination were associated with lower vaccine hesitancy in both rounds. In the second round and among parents with children aged 3−11 years, negative attitudes and exposure to information on SARS-CoV-2 infection after receiving a primary vaccine series were associated with higher vaccine hesitancy, while exposure to experiences shared by vaccine recipients and infectiousness of variants of concern were associated with lower vaccine hesitancy. Regular monitoring of vaccine hesitancy and its associated factors among parents should be conducted to guide health promotion.

Race, Ethnicity, and Health Disparities in US Children With COVID-19: A Review of the Evidence and Recommendations for the Future

Coronavirus disease 2019 (COVID-19) is an important cause of morbidity in children in the United States (U.S.). Moreover, the U.S. has witnessed significant disparities affecting American Indian/Alaska Native, Black, and Hispanic/Latino children, stemming from systemic racism and social-structural inequalities and not differences in innate biological susceptibility. We review what is known on COVID-19 and health disparities in disease burden, access to care, pharmaceutical interventions, and clinical research in children, with a focus on the U.S. context. In addition, we propose strategies to communicate scientific data in ways that do not promote racism and biological susceptibility themes, and to address pediatric disparities in clinical infectious diseases research.

Severe Acute Respiratory Syndrome Coronavirus 2 Vaccination in Children with a History of Multisystem Inflammatory Syndrome in Children: An International Survey

The optimal severe acute respiratory syndrome coronavirus 2 vaccine strategy for patients with a history of multisystem inflammatory syndrome in children (MIS-C) is unclear. We performed an international survey (32 countries) and found substantial variations in vaccine policies. Respondents did not report relapses of MIS-C or other severe inflammatory side effects after severe acute respiratory syndrome coronavirus 2 vaccination in 273 patients with a history of MIS-C.

Neutralization titer biomarker for antibody-mediated prevention of HIV-1 acquisition

The Antibody Mediated Prevention trials showed that the broadly neutralizing antibody (bnAb) VRC01 prevented acquisition of human immunodeficiency virus-1 (HIV-1) sensitive to VRC01. Using AMP trial data, here we show that the predicted serum neutralization 80% inhibitory dilution titer (PT80) biomarker-which quantifies the neutralization potency of antibodies in an individual's serum against an HIV-1 isolate-can be used to predict HIV-1 prevention efficacy. Similar to the results of nonhuman primate studies, an average PT80 of 200 (meaning a bnAb concentration 200-fold higher than that required to reduce infection by 80% in vitro) against a population of probable exposing viruses was estimated to be required for 90% prevention efficacy against acquisition of these viruses. Based on this result, we suggest that the goal of sustained PT80 <200 against 90% of circulating viruses can be achieved by promising bnAb regimens engineered for long half-lives. We propose the PT80 biomarker as a surrogate endpoint for evaluatinon of bnAb regimens, and as a tool for benchmarking candidate bnAb-inducing vaccines.

Effectiveness of BBIBP-CorV, BNT162b2 and mRNA-1273 vaccines against hospitalisations among children and adolescents during the Omicron outbreak in Argentina: A retrospective cohort study

Background

Although paediatric clinical presentations of COVID-19 are usually less severe than in adults, serious illness and death have occurred. Many countries started the vaccination rollout of children in 2021; still, information about effectiveness in the real-world setting is scarce. The aim of our study was to evaluate vaccine effectiveness (VE) against COVID-19-associated-hospitalisations in the 3–17-year population during the Omicron outbreak.

Methods

We conducted a retrospective cohort study including individuals aged 3–17 registered in the online vaccination system of the Buenos Aires Province, Argentina. mRNA-1273 and BNT162b2 were administered to 12–17-year subjects; and BBIBP-CorV to 3–11-year subjects. Vaccinated group had received a two-dose scheme by 12/1/2021. Unvaccinated group did not receive any COVID-19 vaccine between 12/14/2021 and 3/9/2022, which was the entire monitoring period. Vaccine effectiveness (VE) against COVID-19-associated hospitalisations was calculated as (1-OR)x100.

Findings

By 12/1/2021, 1,536,435 individuals aged 3–17 who had received zero or two doses of SARS-CoV-2 vaccines were included in this study. Of the latter, 1,440,389 were vaccinated and 96,046 not vaccinated. VE were 78.0%[68.7–84.2], 76.4%[62.9–84.5] and 80.0%[64.3–88.0] for the entire cohort, 3–11-year (BBIBP-CorV) subgroup and 12–17 (mRNA vaccines) subgroup, respectively. VE for the entire population was 82.7% during the period of Delta and Omicron overlapping circulation and decreased to 67.7% when Omicron was the only variant present.

Interpretation

This report provides evidence of high vaccine protection against associated hospitalisations in the paediatric population during the Omicron outbreak but suggests a decrease of protection when Omicron became predominant. Application of a booster dose in children aged 3–11-year warrants further consideration.

Funding

None.

COVID-19 Vaccination Intentions for Children With Medical Complexity

OBJECTIVES

The chronic conditions and functional limitations experienced by children with medical complexity (CMC) place them at disproportionate risk for COVID-19 transmission and poor outcomes. To promote robust vaccination uptake, specific constructs associated with vaccine hesitancy must be understood. Our objective was to describe demographic, clinical, and vaccine perception variables associated with CMC parents' intention to vaccinate their child against COVID-19.

METHODS

We conducted a cross-sectional survey (June-August 2021) for primary caregivers of CMC between ages 5 to 17 at an academic medical center in the Midwest. Multivariable logistic regression examined associations between vaccination intent and selected covariates.

RESULTS

Among 1330 families, 65.8% indicated vaccination intent. In multivariable models, demographics had minimal associations with vaccination intent; however, parents of younger children (<12 years) had significantly lower adjusted odds of vaccination intent (adjusted odds ratio [95% confidence interval]: 0.26 [0.17-0.3]) compared to parents of older children (≥12 years). CMC with higher severity of illness, ie, those with ≥1 hospitalization in the previous year (versus none) or >1 complex chronic condition (vs 1), had higher adjusted odds of vaccination intent (1.82 [1.14-2.92] and 1.77 [1.16-2.71], respectively). Vaccine perceptions associated with vaccine intention included "My doctor told me to get my child a COVID-19 vaccine" (2.82 [1.74-4.55]); and "I'm concerned about my child's side effects from the vaccine" (0.18 [0.12-0.26]).

CONCLUSIONS

One-third of CMC families expressed vaccine hesitation; however, constructs strongly associated with vaccination intent are potentially modifiable. Pediatrician endorsement of COVID-19 vaccination and careful counseling on side effects might be promising strategies to encourage uptake.