Stronger and durable SARS-CoV-2 immune response to mRNA vaccines in 5-11 years old children with prior COVID-19

A review of Canadian online resources providing information on COVID-19 vaccination for caregivers of children aged 5-11 years

BACKGROUND AND OBJECTIVES

Vaccination is one of the most searched health topics online, yet the quality of resources varies considerably. This study evaluated the quality of Canadian COVID-19 vaccines online resources for caregivers of 5-11-year-old children.

METHODS

We reviewed Canadian public-facing websites from academic pediatric hospitals, governments, professional organizations, and public health authorities until April 22, 2022. Inclusion criteria included English/French resources targeting caregivers of 5-11-year-olds, presented as webpages, FAQs, posters/infographics, and/or videos. Reliability, readability, and understandability/actionability were appraised using the JAMA Benchmark, Flesch-Kincaid Grade Level, and Patient Education Material Assessment Tool for Printable/Audiovisual materials, respectively. We used a content checklist to assess key vaccine topics (e.g., effectiveness and safety). Descriptive statistics included Fisher's exact and ANOVA tests.

RESULTS

Of 1046 websites screened, 43 primary webpage clusters and 141 secondary webpages were analyzed. Twenty (46.5 %), 9 (20.9 %), 7 (16.3 %), and 7 (16.3 %) primary webpage clusters belonged to government, academic pediatric hospitals, professional organizations, and public health authorities, respectively. The mean JAMA Benchmark score was 3.47 ± 0.55 (out of 43). Of 43 clusters, only five (11.6 %) scored at or below a US 6th-grade education level. While 42/43 (97.7 %) primary clusters including printable materials were understandable (PEMAT-P > 70 %), only 7/43 (16.3 %) were considered actionable. The mean content score was 12.65 ± 3.60 (out of 20) among the 43 primary clusters. No differences in quality were seen across organization types, except for actionability (p = 0.016).

CONCLUSIONS

Although most Canadian webpages on COVID-19 vaccines received high scores in understandability, areas requiring improvement in actionability, readability, and content were identified.

Immunological memory to COVID-19 vaccines in immunocompromised and immunocompetent children

Background

Most children in Argentina received only the initial COVID-19 vaccine series, with presumed hybrid immunity after multiple Omicron waves. However, the durability of immune memory, particularly in immunocompromised (IC) children, remains poorly studied.

Methods

A cohort of IC (n=45) and healthy children (HC, n=79) was assessed between 13 to 17 months after receiving two or three doses of BBIBP-CorV and/or BNT162b2. Plasma anti-spike IgG, neutralizing activity and antigen-specific CD4+ and CD8+ T cells against Wuhan and Omicron BA.5 variants were assessed.

Results

Most children remained seropositive after two vaccine doses, but compared with HC, IC exhibited lower neutralizing titers against both Wuhan and Omicron BA.5, particularly those vaccinated with BBIBP-CorV. Even after three vaccine doses, IC showed weaker neutralizing antibody response, CD8+ T cell responses and lower IFN-γ production compared with HC. Integrated analysis of neutralizing antibodies, memory CD4+, and CD8+ T cells revealed a weak immune memory among IC with an important compromise in memory CD8+ T cell responses.

Conclusions

Immunity can last up to 17 months, but reduced effectiveness against new variants highlights the need for updated COVID-19 vaccines, especially for IC children. Additional efforts are essential to enhance vaccination coverage and protect this vulnerable population.

Safety and durability of the immune response after vaccination with the heterologous schedule of anti-COVID-19 vaccines SOBERANA®02 and SOBERANA® Plus in children 3-18 years old

Background

The heterologous three-dose schedule of the protein subunit anti-COVID-19 SOBERANA®02 and SOBERANA® Plus vaccines has proved its safety, immunogenicity and efficacy in pediatric population, but durability of immunogenicity is not yet dilucidated. This study reports the safety and durability of the humoral and cellular responses in children and adolescents 5-7 months after receiving the heterologous vaccine schedule of SOBERANA® 02 and SOBERANA® Plus.

Methods

Children participating in a phase I/II clinical trial were followed-up for 5-7 months after the last dose. They were clinically examined by medical doctors, and their parents were interviewed searching for long-term adverse events. Blood samples were collected to evaluate the duration of humoral and cellular immune responses. Sera were tested for the presence of SARS-CoV-2 nucleocapsid (N) protein.

Results

There were no reports of severe adverse events such as coagulation disorders, myocarditis, or pericarditis. None of the participants who withdrew from the trial during the follow-up period did so due to post-vaccination adverse events. The humoral response waned in time for N-negative children, but levels of specific and neutralizing antibodies remained similar to those attained after the second dose of SOBERANA® 02 in the heterologous schedule. Neutralizing antibodies against SARS-CoV-2 D614G and omicron BA.1 were detected 5-7 months post-vaccination. RBD-specific IFN-γ secreting cells showed no significant change compared to levels following primary immunization, in both N-negative and N-positive children.

Conclusions

The vaccination regimen was safe over time, and both humoral and cellular immunity persisted in the vaccinated population aged 3-18 years, 5-7 months after receiving the heterologous SOBERANA® 02 and SOBERANA® Plus vaccine schedule.Trial registry: https://rpcec.sld.cu/trials/RPCEC00000374-En.

Hybrid immunity after BNT162b2 Covid-19 vaccine administration in children aged 5 to 11 years

BACKGROUND

The immune response to coronavirus disease 2019 (COVID-19) vaccination is stronger among adults with prior infection (hybrid immunity). It is important to understand if children demonstrate a similar response to better inform vaccination strategies. Our study investigated the humoral response after BNT162b2 COVID-19 vaccine doses in SARS-CoV-2 naïve and recovered children (5-11 years).

METHODS

A multi-institutional, longitudinal, prospective cohort study was conducted. Children were enrolled in a case-ascertained antibody surveillance study in Ottawa, Ontario from September/2020-March/2021; at least one household member was severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) positive on RT-PCR. In November 2021, BNT162b2 COVID-19 vaccine was authorized for children aged 5-11 in Canada. Children enrolled in the surveillance study intending to receive two vaccine doses were invited to participate in this study from November 2021-April 2022. Main exposure was prior SARS-CoV-2 infection, defined by positive RT-PCR or SARS-CoV-2 anti-N IgG antibody presence. Primary outcome was spike IgG antibody levels measured following the first vaccine dose (2-3 weeks) and second vaccine dose (3-4 weeks).

RESULTS

Of the 153 eligible children, 75 participants (median age 8.9 IQR (7.4, 10.2) years; 38 (50.7 %) female; 59 (78.7 %) Caucasian) had complete follow-up. Fifty-four (72 %) children had prior SARS-COV-2 infection. Spike IgG antibody levels are significantly higher in SARS-CoV-2 recovered participants after receiving the first dose (p < 0.001) and the second (p = 0.01) compared to infection naïve children.

CONCLUSIONS AND RELEVANCE

SARS-CoV-2 recovered children (5-11 years) demonstrated higher antibody levels following first BNT162b2 vaccine dose compared with naïve children. Most reached antibody saturation two to three weeks after the first dose; a second dose didn't change the saturation level. A single vaccine dose in SARS-CoV-2 recovered children may be equivalent or superior to a 2-dose primary series in naïve children. Further research is needed on the durability and quality of a single vaccine dose in this population.

Safety and antibody response of the BNT162b2 SARS-CoV-2 vaccine in children aged 5-11 years with underlying diseases: A prospective observational study

BACKGROUND

Data on the safety and antibody response of the BNT162b2 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccine in children aged 5-11 years with underlying diseases are limited. Thus, our study aimed to address this gap.

METHODS

This prospective observational study investigated the antibody titers for SARS-CoV-2 spike protein receptor-binding domain (S-IgG) and nucleocapsid protein (N-IgG) in patients aged 5-11 years with chronic underlying diseases following two doses of BNT162b2. Additionally, a questionnaire was used to assess adverse events (AEs) arising within 7 days after each dose. Data on severe AEs arising within 28 days after each dose were extracted from the patients' electronic medical records.

RESULTS

Among 122 patients, 24.6% (30/122) were immunocompromised. Furthermore, 79 patients experienced at least one AE following vaccination, but all recovered without sequelae, including one severe case after the first dose. The seropositivity rate after the second dose was 99.1% (116/117). Excluding 19 N-IgG-positive patients, the geometric mean antibody titer (GMT) was significantly higher in immunocompetent patients than in immunocompromised patients (1496 U/mL [95% confidence interval 1199-1862] vs. 472 U/mL [200-1119], p = 0.035). Additionally, the GMT of S-IgG was higher in N-IgG-positive patients than in N-IgG-negative patients (8203 [5847-11482] U/mL vs. 1127 [855-1486] U/mL, p < 0.001).

CONCLUSIONS

BNT162b2 is acceptably safe and immunogenic for children aged 5-11 years with underlying diseases. Although seroconversion was satisfactory in immunocompromised patients, the titers were lower than in immunocompetent patients.