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Efficacy, Immunogenicity and Safety of COVID-19 Vaccines and COVID-19 Vaccination Strategies

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A special issue of Vaccines (ISSN 2076-393X). This special issue belongs to the section "Vaccine Efficacy and Safety".

Deadline for manuscript submissions: 31 January 2025 | Viewed by 21753

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Dr. Pedro Plans-Rubió

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1. Public Health Agency of Catalonia, Department of Health of Catalonia, 08005 Barcelona, Spain
2. Ciber of Epidemiology and Public Health (CIBERESP), 28028 Madrid, Spain
Interests: vaccination programs; preventive interventions; epidemiology of vaccine-preventable diseases; seroepidemiology; cost-effectiveness analysis of vaccines and health programs; metabolic risk factors of chronic diseases; health policy
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Dear Colleagues,

COVID-19 vaccines have reduced the incidence and mortality from SARS-CoV-2 infections since the first vaccines were administered. Randomized clinical trials and observational studies can be developed to assess vaccine-induced immunity protection, vaccine efficacy in preventing SARS-CoV-2 infection and symptomatic disease, and vaccine safety. The efficacy and safety of COVID-19 vaccines can vary depending on the vaccine technology, target population and circulating virus.

Post-marketing research of efficacy and safety levels associated with COVID-19 vaccines is necessary to assess how available vaccines respond to new SARS-CoV-2 variants.

COVID-19 vaccination programs must overcome many challenges to achieve and maintain high protection levels in the population. Studies assessing knowledge and perceptions about the efficacy and safety of COVID-19 vaccines are necessary to develop communication strategies to reduce vaccine hesitancy and increase vaccine acceptance.

This Special Issue of Vaccines seeks to collect high-quality articles presenting the results of studies on immunogenicity, efficacy, and safety of COVID-19 vaccines; post-marketing assessment of COVID-19 vaccine immunogenicity, efficacy, and safety; COVID-19 vaccination programs challenges related to efficacy and safety; and knowledge, perception, and communication of COVID-19 vaccine efficacy and safety.

Dr. Pedro Plans-Rubió
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Vaccines is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

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Published Papers (9 papers)

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14 pages, 1892 KiB

Open AccessArticle

Safety and Immunogenicity of Intranasal Razi Cov Pars as a COVID-19 Booster Vaccine in Adults: Promising Results from a Groundbreaking Clinical Trial

by Mohammad Hossein Fallah Mehrabadi, Monireh Hajimoradi, Ali Es-haghi, Saeed Kalantari, Mojtaba Noofeli, Ali Rezaei Mokarram, Seyed Hossein Razzaz, Maryam Taghdiri, Ladan Mokhberalsafa, Fariba Sadeghi, Vahideh Mohseni, Safdar Masoumi, Rezvan Golmoradi-Zadeh, Mohammad Hasan Rabiee, Masoud Solaymani-Dodaran and Seyed Reza Banihashemi

Vaccines 2024, 12(11), 1255; https://doi.org/10.3390/vaccines12111255 - 5 Nov 2024

Viewed by 844

Abstract

Protective antibodies in the upper respiratory tract prevent the spread of COVID-19 in the community. Intranasal vaccines could raise the specific secretory IgA and IgG levels. This is a single-center, randomized, double-blind, placebo-controlled clinical trial to evaluate the safety and immunogenicity of Razi Cov Pars (RCP) intranasal recombinant protein subunit COVID-19 vaccine as a booster in adults. We compared specific IgG and IgA levels in the intranasal RCP group (n = 97) versus placebo (n = 96) in serum, saliva, and nasal mucosal secretions on days 0 and 14 and reported their Geometric Mean Ratios (GMR) and 95% confidence intervals (CI). We showed significant increases in IgA and IgG anti-RBD in the nasal mucosa in the RCP group, but their increase was not detectable in the serum and saliva. Anti-spike IgA in the nasal mucosa also increased in the RCP group compared to the placebo. This increase against the COVID-19 variant Omicron was also similar to that of the Wuhan. We detected no serious adverse reactions or anaphylaxis and all adverse events resolved completely during the follow-up period and were similar in both groups. Intranasal RCP is safe, stimulates the respiratory mucosal immunity, and could be a booster on various COVID-19 vaccines and be effective against new virus variants. Full article

(This article belongs to the Special Issue Efficacy, Immunogenicity and Safety of COVID-19 Vaccines and COVID-19 Vaccination Strategies)

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13 pages, 2566 KiB

Open AccessArticle

Evaluation of Vaccine Strategies among Healthcare Workers during COVID-19 Omicron Outbreak in Taiwan

by Min-Ru Lin, Chung-Guei Huang, Cheng-Hsun Chiu and Chih-Jung Chen

Vaccines 2024, 12(9), 1057; https://doi.org/10.3390/vaccines12091057 - 17 Sep 2024

Viewed by 1573

Abstract

Background/Objectives: This study aimed to assess the reactogenicity and immunogenicity of various SARS-CoV-2 vaccines and compare their protective effects against COVID-19 among healthcare workers (HCWs) during the Omicron outbreak in Taiwan. Methods: Conducted from March 2021 to July 2023, this prospective observational study included healthy HCWs without prior COVID-19 immunization. Participants chose between adenovirus-vectored (AstraZeneca), mRNA (Moderna, BioNTech-Pfizer), and protein-based (Medigen, Novavax) vaccines. Blood samples were taken at multiple points to measure neutralizing antibody (nAb) titers, and adverse events (AEs) were recorded via questionnaires. Results: Of 710 HCWs, 668 (94.1%) completed three doses, and 290 (40.8%) received a fourth dose during the Omicron outbreak. AEs were more common with AstraZeneca and Moderna vaccines, while Medigen caused fewer AEs. Initial nAb titers were highest with Moderna but waned over time regardless of the vaccine. Booster doses significantly increased nAb titers, with the highest levels observed in Moderna BA1 recipients. The fourth dose significantly reduced COVID-19 incidence, with Moderna BA1 being the most effective. Conclusions: Regular booster doses, especially with mRNA and adjuvant-protein vaccines, effectively enhance nAb levels and reduce infection rates, providing critical protection for frontline HCWs during variant outbreaks. Full article

(This article belongs to the Special Issue Efficacy, Immunogenicity and Safety of COVID-19 Vaccines and COVID-19 Vaccination Strategies)

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15 pages, 1882 KiB

Open AccessArticle

Baseline Gut Microbiota Was Associated with Long-Term Immune Response at One Year Following Three Doses of BNT162b2

by Li-Na Zhang, Jing-Tong Tan, Ho-Yu Ng, Yun-Shi Liao, Rui-Qi Zhang, Kwok-Hung Chan, Ivan Fan-Ngai Hung, Tommy Tsan-Yuk Lam and Ka-Shing Cheung

Vaccines 2024, 12(8), 916; https://doi.org/10.3390/vaccines12080916 - 14 Aug 2024

Viewed by 1009

Abstract

Background: This study explored neutralizing IgG antibody levels against COVID-19 decline over time post-vaccination. We conducted this prospective cohort study to investigate the function of gut microbiota in the host immune response following three doses of BNT162b2. Methods: Subjects who received three doses of BNT162b2 were recruited from three centers in Hong Kong. Blood samples were obtained before the first dose and at the one-year timepoint for IgG ELISA to determine the level of neutralizing antibody (NAb). The primary outcome was a high immune response (NAb > 600 AU/mL). We performed shotgun DNA metagenomic sequencing on baseline fecal samples to identify bacterial species and metabolic pathways associated with high immune response using linear discriminant analysis effect size analysis. Results: A total of 125 subjects were recruited (median age: 52 years [IQR: 46.2–59.0]; male: 43 [34.4%]), and 20 were regarded as low responders at the one-year timepoint. Streptococcus parasanguinis (log₁₀LDA score = 2.38, p = 0.003; relative abundance of 2.97 × 10⁻⁵ vs. 0.03%, p = 0.001), Bacteroides stercoris (log₁₀LDA score = 4.29, p = 0.024; relative abundance of 0.14% vs. 2.40%, p = 0.014) and Haemophilus parainfluenzae (log₁₀LDA score = 2.15, p = 0.022; relative abundance of 0.01% vs. 0, p = 0.010) were enriched in low responders. Bifidobacterium pseudocatenulatum (log₁₀LDA score = 2.99, p = 0.048; relative abundance of 0.09% vs. 0.36%, p = 0.049) and Clostridium leptum (log₁₀LDA score = 2.38, p = 0.014; relative abundance of 1.2 × 10⁻⁵% vs. 0, p = 0.044) were enriched in high responders. S. parasanguinis was negatively correlated with the superpathway of pyrimidine ribonucleotides de novo biosynthesis (log₁₀LDA score = 2.63), which contributes to inflammation and antibody production. H. parainfluenzae was positively correlated with pathways related to anti-inflammatory processes, including the superpathway of histidine, purine, and pyrimidine biosynthesis (log₁₀LDA score = 2.14). Conclusion: Among three-dose BNT162b2 recipients, S. parasanguinis, B. stercoris and H. parainfluenzae were associated with poorer immunogenicity at one year, while B. pseudocatenulatum and C. leptum was associated with a better response. Full article

(This article belongs to the Special Issue Efficacy, Immunogenicity and Safety of COVID-19 Vaccines and COVID-19 Vaccination Strategies)

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13 pages, 2344 KiB

Open AccessArticle

Intradermal Fractional ChAdOx1 nCoV-19 Booster Vaccine Induces Memory T Cells: A Follow-Up Study

by Ratchanon Sophonmanee, Perawas Preampruchcha, Jomkwan Ongarj, Bunya Seeyankem, Porntip Intapiboon, Smonrapat Surasombatpattana, Supattra Uppanisakorn, Pasuree Sangsupawanich, Sarunyou Chusri and Nawamin Pinpathomrat

Vaccines 2024, 12(2), 109; https://doi.org/10.3390/vaccines12020109 - 23 Jan 2024

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Abstract

The administration of viral vector and mRNA vaccine booster effectively induces humoral and cellular immune responses. Effector T cell responses after fractional intradermal (ID) vaccination are comparable to those after intramuscular (IM) boosters. Here, we quantified T cell responses after booster vaccination. ChAdOx1 nCoV-19 vaccination induced higher numbers of S1-specific CD8⁺ memory T cells, consistent with the antibody responses. Effector memory T cell phenotypes elicited by mRNA vaccination showed a similar trend to those elicited by the viral vector vaccine booster. Three months post-vaccination, cytokine responses remained detectable, confirming effector T cell responses induced by both vaccines. The ID fractional dose of ChAdOx1 nCoV-19 elicited higher effector CD8⁺ T cell responses than IM vaccination. This study confirmed that an ID dose-reduction vaccination strategy effectively stimulates effector memory T cell responses. ID injection could be an improved approach for effective vaccination programs. Full article

(This article belongs to the Special Issue Efficacy, Immunogenicity and Safety of COVID-19 Vaccines and COVID-19 Vaccination Strategies)

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25 pages, 2475 KiB

Open AccessArticle

Mathematical Optimization Strategy for Effectiveness Profile Estimation in Two-Dose Vaccines and Its Use in Designing Improved Vaccination Strategies Focused on Pandemic Containment

by Óscar A. González-Sánchez, Daniel Zaldívar, Erik Cuevas and L. Javier González-Ortiz

Vaccines 2024, 12(1), 81; https://doi.org/10.3390/vaccines12010081 - 12 Jan 2024

Viewed by 1362

Abstract

Since late 2019, most efforts to control the COVID-19 pandemic have focused on developing vaccines. By mid-2020, some vaccines fulfilled international regulations for their application. However, these vaccines have shown a decline in effectiveness several weeks after the last dose, highlighting the need to optimize vaccine administration due to supply chain limitations. While methods exist to prioritize population groups for vaccination, there is a lack of research on how to optimally define the time between doses when two-dose vaccines are administrated to such groups. Under such conditions, modeling the real effect of each vaccine on the population is critical. Even though several efforts have been made to characterize vaccine effectiveness profiles, none of these initiatives enable characterization of the individual effect of each dose. Thus, this paper presents a novel methodology for estimating the vaccine effectiveness profile. It addresses the vaccine characterization problem by considering a deconvolution of relevant data profiles, treating them as an optimization process. The results of this approach enabled the independent estimation of the effectiveness profiles for the first and second vaccine doses and their use to find sweet spots for designing efficient vaccination strategies. Our methodology can enable a more effective and efficient contemporary response against the COVID-19 pandemic, as well as for any other disease in the future. Full article

(This article belongs to the Special Issue Efficacy, Immunogenicity and Safety of COVID-19 Vaccines and COVID-19 Vaccination Strategies)

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13 pages, 563 KiB

Open AccessArticle

Assessment of COVID-19 Vaccine Acceptance and Its Associated Factors during the Crisis: A Community-Based Cross-Sectional Study in Benin

by Sètondji Géraud Roméo Padonou, Clément Kakaï Glèlè, Manfred Accrombessi, Bayode Romeo Adegbite, Edouard Dangbenon, Houssaïnatou Bah, Enangnon Akogbeto, Ali Imorou Bah Chabi, Landry Kaucley, Salifou Sourakatou, Ange Dossou, Achille Batonon, Tania Bissouma-Ledjou and Benjamin Hounkpatin

Vaccines 2023, 11(6), 1104; https://doi.org/10.3390/vaccines11061104 - 16 Jun 2023

Cited by 2 | Viewed by 2030

Abstract

Background: Having a maximum number of people vaccinated was the objective to control the COVID-19 pandemic. We report in this manuscript the factors associated with the willingness to be vaccinated against COVID-19 during the pandemic period. Methods: From April to May 2022, a community-based cross-sectional survey was performed. Participants were randomly selected from four districts in Benin (taking into account the COVID-19 prevalence). Mixed-effect logistic regression models were used to identify the variables associated with COVID-19 vaccine acceptance. Results: A total of 2069 participants were included. The proportion of vaccine acceptance was 43.3%. A total of 24.2% were vaccinated and showed proof of vaccination. The population’s request for vaccination was higher after the third epidemic wave. The district of residence, the education level, a fear of being infected, the channel of information, poor medical conditions, a good knowledge of the transmission mode and symptoms, and good behaviors were significantly associated with vaccine acceptance. Conclusion: The overall acceptance of the COVID-19 vaccine in the Beninese population was relatively high. However, vaccine campaigns in areas with a low acceptance as well as the disclosure of information, particularly on our knowledge of the disease and the safety, side effects, and effectiveness of the COVID-19 vaccines, should be strengthened with adapted and consistent messages. Full article

(This article belongs to the Special Issue Efficacy, Immunogenicity and Safety of COVID-19 Vaccines and COVID-19 Vaccination Strategies)

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9 pages, 1116 KiB

Open AccessPerspective

The Immunologic Downsides Associated with the Powerful Translation of Current COVID-19 Vaccine mRNA Can Be Overcome by Mucosal Vaccines

by Maurizio Federico

Vaccines 2024, 12(11), 1281; https://doi.org/10.3390/vaccines12111281 - 14 Nov 2024

Viewed by 10032

Abstract

The action of mRNA-based vaccines requires the expression of the antigen in cells targeted by lipid nanoparticle–mRNA complexes. When the vaccine antigen is not fully retained by the producer cells, its local and systemic diffusion can have consequences depending on both the levels of antigen expression and its biological activity. A peculiarity of mRNA-based COVID-19 vaccines is the extraordinarily high amounts of the Spike antigen expressed by the target cells. In addition, vaccine Spike can be shed and bind to ACE-2 cell receptors, thereby inducing responses of pathogenetic significance including the release of soluble factors which, in turn, can dysregulate key immunologic processes. Moreover, the circulatory immune responses triggered by the vaccine Spike is quite powerful, and can lead to effective anti-Spike antibody cross-binding, as well as to the emergence of both auto- and anti-idiotype antibodies. In this paper, the immunologic downsides of the strong efficiency of the translation of the mRNA associated with COVID-19 vaccines are discussed together with the arguments supporting the idea that most of them can be avoided with the advent of next-generation, mucosal COVID-19 vaccines. Full article

(This article belongs to the Special Issue Efficacy, Immunogenicity and Safety of COVID-19 Vaccines and COVID-19 Vaccination Strategies)

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17 pages, 1797 KiB

Open AccessSystematic Review

Serological Responses after a Fourth Dose of SARS-CoV-2 Vaccine in Solid Organ Transplant Recipients: A Systematic Review and Meta-Analysis

by Yameng Mu, Hongxiao Wu, Zhouling Jiang, Kehang Liu, Xiaoyu Xue, Wei Zhang and Zhihai Chen

Vaccines 2023, 11(7), 1130; https://doi.org/10.3390/vaccines11071130 - 21 Jun 2023

Cited by 3 | Viewed by 1421

Abstract

The humoral immune response and safety of the fourth dose of the coronavirus disease 2019 (COVID-19) vaccine in solid organ transplant (SOT) recipients need to be fully elucidated. We conducted a systematic review and meta-analysis to assess the efficacy and safety associated with this additional dose of the COVID-19 vaccine in the SOT recipients. A comprehensive search was conducted to identify studies on SOT patients without prior natural SARS-CoV-2 infection who received the fourth dose of the COVID-19 vaccine. Serological antibody responses following vaccination were synthesized by a meta-analysis of proportions. The proportions for each outcome were integrated by using a random-effects model. Approximately 56–92% of the SOT patients developed a humoral immune response, and the pooled seroprevalence rate was 75% (95% confidence interval [CI], 62–82%) after administering the third vaccine dose. Following the fourth dose of vaccination, approximately 76–95% of the patients developed a humoral immune response. The pooled seroprevalence rate after the fourth dose was 85% (95% CI, 79–91%). Of the patients who initially tested seronegative after the second dose, approximately 22–76% of patients subsequently became seropositive after the third dose. The pooled seroconversion rate for the third dose was 47% (95% CI, 31–64%). Among the patients who were seronegative after the third dose, approximately 25–76% turned seropositive after the fourth dose. The pooled seroconversion rate after the fourth dose was 51% (95% CI, 40–63%). Safety data were reported in three studies, demonstrating that adverse effects following the fourth dose were generally mild, and patients with these adverse effects did not require hospitalization. No transplant rejection or serious adverse events were observed. A fourth dose of the COVID-19 vaccine in SOT recipients was associated with an improved humoral immune response, and the vaccine was considered relatively safe. Full article

(This article belongs to the Special Issue Efficacy, Immunogenicity and Safety of COVID-19 Vaccines and COVID-19 Vaccination Strategies)

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7 pages, 236 KiB

Open AccessCommentary

Challenges in Assessing COVID-19 Vaccines Safety Signals—The Case of ChAdOx1 nCoV-19 Vaccine and Corneal Graft Rejection

by Christelle Bizimungu, Martine Sabbe, Françoise Wuillaume, Jamila Hamdani, Philippe Koch and Jean-Michel Dogné

Vaccines 2023, 11(5), 954; https://doi.org/10.3390/vaccines11050954 - 6 May 2023

Cited by 3 | Viewed by 1332

Abstract

The rapid and large-scale roll-out of new COVID-19 vaccines has led to unprecedented challenges in assessing vaccine safety. In 2021, the European Medicines Agency (EMA) processed about 1.7 million safety reports related to COVID-19 vaccines in the EudraVigilance (EV) database and identified more than 900 potential signals. Beyond the large amount of information to be processed, the evaluation of safety signals has faced several difficulties and limitations, both in the assessment of case reports and in the investigation of databases. The evaluation of a signal of corneal graft rejection (CGR) with Vaxzevria^® was no exception to this. In this commentary, we present the challenges encountered in making regulatory decisions in the context of evolving evidence and knowledge. The pandemic crisis emphasised the importance of quick and proactive communication to address the many questions and, above all, to ensure the transparency of safety data. Full article

(This article belongs to the Special Issue Efficacy, Immunogenicity and Safety of COVID-19 Vaccines and COVID-19 Vaccination Strategies)

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