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Vaccines Jan 2022(1) Background: The objective of this study was to assess the effectiveness of SARS-CoV-2 vaccines in terms of prevention of disease and transmission in the pre-Delta... (Review)
Review
(1) Background: The objective of this study was to assess the effectiveness of SARS-CoV-2 vaccines in terms of prevention of disease and transmission in the pre-Delta era. The evaluation was narrowed to two mRNA vaccines and two modified adenovirus-vectored vaccines. (2) Methods: The overall risk of any SARS-CoV-2 infection confirmed by positive real-time Polymerase Chain Reaction (PCR) test was estimated in partially and fully vaccinated individuals. The evidence synthesis was pursued through a random-effects meta-analysis. The effect size was expressed as relative risk (RR) and RRR (RR reduction) of SARS-CoV-2 infection following vaccination. Heterogeneity was investigated through a between-study heterogeneity analysis and a subgroup meta-analysis. (3) Results: The systematic review identified 27 studies eligible for the quantitative synthesis. Partially vaccinated individuals presented a RRR = 73% (95%CI = 59-83%) for positive SARS-CoV-2 PCR (RR = 0.27) and a RRR=79% (95%CI = 30-93%) for symptomatic SARS-CoV-2 PCR (RR = 0.21). Fully vaccinated individuals showed a RRR = 94% (95%CI = 88-98%) for SARS-CoV-2 positive PCR (RR = 0.06) compared to unvaccinated individuals. The full BNT162b2 vaccination protocol achieved a RRR = 84-94% against any SARS-CoV-2-positive PCR and a RRR = 68-84% against symptomatic positive PCR. (4) Conclusions: The meta-analysis results suggest that full vaccination might block transmission. In particular, the risk of SARS-CoV-2 infection appeared higher for non-B.1.1.7 variants and individuals aged ≥69 years. Considering the high level of heterogeneity, these findings must be taken with caution. Further research on SARS-CoV-2 vaccine effectiveness against emerging SARS-CoV-2 variants is encouraged.
PubMed: 35214615
DOI: 10.3390/vaccines10020157 -
Clinical Infectious Diseases : An... Sep 2022Rare cases of thrombosis and thrombocytopenia (thrombosis with thrombocytopenia syndrome [TTS]) have been associated with 2 coronavirus disease 2019 adenovirus vector... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Rare cases of thrombosis and thrombocytopenia (thrombosis with thrombocytopenia syndrome [TTS]) have been associated with 2 coronavirus disease 2019 adenovirus vector vaccines: the ChAdOx1 nCoV-19 Vaxzevria vaccine (Oxford/AstraZeneca) and the JNJ-7836735 Johnson & Johnson vaccine (Janssen). It is unknown if TTS is a class-mediated effect of adenovirus-based vaccines or if it could worsen known hypercoagulable states. Since most cases of TTS happen in women of childbearing age, pregnancy is a crucial risk factor to assess. Understanding these risks is important for advising vaccine recipients and future adenovirus vector vaccine development.
METHODS
To explore the potential associations of adenovirus-based vaccine components with symptoms of TTS in the general clinical trial population and in pregnant women in clinical trials, we conducted a systematic review and meta-analysis of adenovirus-based vector vaccines to document cases of thrombocytopenia, coagulopathy, and or pregnancy from 1 January 1966 to 9 August 2021.
RESULTS
We found 167 articles from 159 studies of adenovirus vector-based vaccines, 123 of which targeted infectious diseases. In the general population, 20 studies reported an event of thrombocytopenia and 20 studies indicated some coagulopathy. Among pregnant women, of the 28 studies that reported a total of 1731 pregnant women, thrombocytopenia or coagulopathy were not reported.
CONCLUSIONS
In this systematic review and meta-analysis, there was no class-wide effect of adenovirus vector vaccines toward thrombocytopenia or coagulopathy events in the general population or in pregnant women.
Topics: Adenoviridae; Adenovirus Vaccines; COVID-19; ChAdOx1 nCoV-19; Female; Humans; Pregnancy; Thrombocytopenia; Thrombosis; Vaccines
PubMed: 35134164
DOI: 10.1093/cid/ciac080 -
Blood Coagulation & Fibrinolysis : An... Mar 2022AstraZeneca coronavirus disease 2019 (COVID-19) vaccinations have recently been implicated in thromboembolism formations. Our aim was to investigate the outcomes of... (Meta-Analysis)
Meta-Analysis
AstraZeneca coronavirus disease 2019 (COVID-19) vaccinations have recently been implicated in thromboembolism formations. Our aim was to investigate the outcomes of patients with thromboembolic events following the AstraZeneca vaccine (ChAdOx1 nCoV-19, AZD1222). A literature search was performed from December 2019 to September 2021. Eligible studies must report participants older than 18 years vaccinated with AstraZeneca and outcomes of thromboembolic events. Pooled mean or proportion were analyzed using a random-effects model. A total of 45 unique studies (number of patients = 144, 64.6% women, mean age 21-68 years) were included. The most common presenting adverse events were headache (12.1%), intracerebral hemorrhage (7.5%), and hemiparesis (7%). The most common thromboembolic adverse events were cerebral venous sinus thrombosis (38.5%) and deep vein thrombosis/pulmonary embolism (21.1%). The most common radiologic finding were intracerebral hemorrhage and cerebral venous thrombosis. Laboratory findings included thrombocytopenia (75%) and hypofibrinogenemia (41%). On admission, 64 patients tested positive for PF4-Heparin ELISA assay (80%). Seventy-four patients were hospitalized with 22 being admitted to the ICU. A total of 78 patients recovered while 39 patients died. This meta-analysis presents evidence to suggest vaccine-induced immune thrombotic thrombocytopenia (VITT) following AstraZeneca vaccine. Clinical practice must, therefore, account for the possibility of VITT and subsequent embolic events in certain individuals' postvaccination with adenovirus-based COVID-19 vaccines. Serum anti-PF4 suggests diagnostic value for VITT and could subsequently inform treatment choices in such instances.
Topics: Adult; Aged; COVID-19; COVID-19 Vaccines; ChAdOx1 nCoV-19; Female; Humans; Male; Middle Aged; SARS-CoV-2; Thromboembolism; Vaccination; Young Adult
PubMed: 34980833
DOI: 10.1097/MBC.0000000000001113 -
Frontiers in Immunology 2021The World Health Organization declared the coronavirus disease 2019 (COVID-19) pandemic on March 11, 2020. Two vaccine types were developed using two different...
INTRODUCTION
The World Health Organization declared the coronavirus disease 2019 (COVID-19) pandemic on March 11, 2020. Two vaccine types were developed using two different technologies: viral vectors and mRNA. Thrombosis is one of the most severe and atypical adverse effects of vaccines. This study aimed to analyze published cases of thrombosis after COVID-19 vaccinations to identify patients' features, potential pathophysiological mechanisms, timing of appearance of the adverse events, and other critical issues.
MATERIALS AND METHODS
We performed a systematic electronic search of scientific articles regarding COVID-19 vaccine-related thrombosis and its complications on the PubMed (MEDLINE) database and through manual searches. We selected 10 out of 50 articles from February 1 to May 5, 2021 and performed a descriptive analysis of the adverse events caused by the mRNA-based Pfizer and Moderna vaccines and the adenovirus-based AstraZeneca vaccine.
RESULTS
In the articles on the Pfizer and Moderna vaccines, the sample consisted of three male patients with age heterogeneity. The time from vaccination to admission was ≤3 days in all cases; all patients presented signs of petechiae/purpura at admission, with a low platelet count. In the studies on the AstraZeneca vaccine, the sample consisted of 58 individuals with a high age heterogeneity and a high female prevalence. Symptoms appeared around the ninth day, and headache was the most common symptom. The platelet count was below the lower limit of the normal range. All patients except one were positive for PF4 antibodies. The cerebral venous sinus was the most affected site. Death was the most prevalent outcome in all studies, except for one study in which most of the patients remained alive.
DISCUSSION
Vaccine-induced thrombotic thrombocytopenia (VITT) is an unknown nosological phenomenon secondary to inoculation with the COVID-19 vaccine. Several hypotheses have been formulated regarding its physiopathological mechanism. Recent studies have assumed a mechanism that is assimilable to heparin-induced thrombocytopenia, with protagonist antibodies against the PF4-polyanion complex. Viral DNA has a negative charge and can bind to PF4, causing VITT. New experimental studies have assumed that thrombosis is related to a soluble adenoviral protein spike variant, originating from splicing events, which cause important endothelial inflammatory events, and binding to endothelial cells expressing ACE2.
CONCLUSION
Further studies are needed to better identify VITT's pathophysiological mechanisms and genetic, demographic, or clinical predisposition of high-risk patients, to investigate the correlation of VITT with the different vaccine types, and to test the significance of the findings.
Topics: 2019-nCoV Vaccine mRNA-1273; Antigen-Antibody Complex; BNT162 Vaccine; COVID-19; Cerebral Veins; ChAdOx1 nCoV-19; Female; Headache; Humans; Mass Vaccination; Platelet Factor 4; SARS-CoV-2; Sex Factors; Survival Analysis; Thrombosis
PubMed: 34912330
DOI: 10.3389/fimmu.2021.729251 -
The Lancet Regional Health. Europe Jan 2022For safety assessment in clinical trials, adverse events (AEs) are reported for the drug under evaluation and compared with AEs in the placebo group. Little is known...
BACKGROUND
For safety assessment in clinical trials, adverse events (AEs) are reported for the drug under evaluation and compared with AEs in the placebo group. Little is known about the nature of the AEs associated with clinical trials of SARS-CoV-2 vaccines and the extent to which these can be traced to nocebo effects, where negative treatment-related expectations favor their occurrence.
METHODS
In our systematic review, we compared the rates of solicited AEs in the active and placebo groups of SARS-CoV-2 vaccines approved by the Western pharmaceutical regulatory agencies.We implemented a search strategy to identify trial-III studies of SARS-CoV-2 vaccines through the PubMed database. We adopted the PRISMA Statement to perform the study selection and the data collection and identified three trial: two mRNA-based (38403 participants) and one adenovirus type (6736 participants).
FINDINGS
Relative risks showed that the occurrence of AEs reported in the vaccine groups was higher compared with the placebo groups. The most frequently AEs in both groups were fatigue, headache, local pain, as injection site reactions, and myalgia. In particular, for first doses in placebo recipients, fatigue was reported in 29% and 27% in BNT162b2 and mRNA-1273 groups, respectively, and in 21% of Ad26.COV2.S participants. Headache was reported in 27% in both mRNA groups and in 24% of Ad26.COV2.S recipients. Myalgia was reported in 10% and 14% in mRNA groups (BNT162b2 and mRNA-1273, respectively) and in 13% of Ad26.COV2.S participants. Local pain was reported in 12% and 17% in mRNA groups (BNT162b2 and mRNA-1273, respectively), and in 17% of Ad26.COV2.S recipients. These AEs are more common in the younger population and in the first dose of placebo recipients of the mRNA vaccines.
INTERPRETATION
Our results are in agreement with the expectancy theory of nocebo effects and suggest that the AEs associated with COVID-19 vaccines may be related to the nocebo effect.
FUNDING
Fondazione CRT - Cassa di Risparmio di Torino, IT (grant number 66346, "GAIA-MENTE" 2019).
PubMed: 34729549
DOI: 10.1016/j.lanepe.2021.100253 -
Frontiers in Immunology 2021There is a significant research gap in meta-analysis on the efficacy and safety of coronavirus disease 2019 (COVID-19) vaccines. This study analyzed the efficacy of... (Meta-Analysis)
Meta-Analysis
There is a significant research gap in meta-analysis on the efficacy and safety of coronavirus disease 2019 (COVID-19) vaccines. This study analyzed the efficacy of COVID-19 vaccines. Published phase I, phase II, and phase III trials analyzing safety and immunogenicity and phase III randomized clinical trials evaluating the efficacy of COVID-19 vaccines were included. We searched MEDLINE, Scopus, and The Lancet for published articles evaluating the relative reduction in COVID-19 risk after vaccination. Selected literatures were published between December 15, 2019 and May 15, 2021 on the safety, efficacy, and immunogenicity of COVID-19 vaccines. This meta-analysis included studies that confirmed cases of COVID-19 using reverse transcriptase polymerase chain reaction. This study detected 8,926 eligible research articles published on COVID-19 vaccines. Of these, 25 studies fulfilled the inclusion criteria. Among the selected articles, 19 randomized clinical trials, 2 non-randomized clinical trials, and 3 observational studies were analyzed. Seven (28%) studies were included in the meta-analysis. The efficacy of the adenovirus vector vaccine was 73% (95% CI = 69-77) and that of the messenger RNA (mRNA) vaccine was 85% (95% CI = 82-88) in participants aged ≥18 years. There are no reports of clinical trials in participants aged under 16 years. The production of neutralizing antibodies against receptor-binding domains (RBDs) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in >90% of the vaccinated samples was reported within 0-30 days of the first or the second dose of the vaccine. Pain at the injection site was the most common local symptom in people receiving mRNA vaccines (29%-85% of participants). Fever (0.2%-95%) was the most prevalent in people receiving adenovirus vector vaccines, and fatigue (8.4%-55%) was the most common side effect in people receiving the mRNA vaccines. Studies suggest that mRNA vaccines and adenovirus vector vaccines can provide moderate to high protection against COVID-19 infection in people over 18 years. Evidence of the long-term protection of the vaccines in people aged under 16 years against the multiple variants of COVID-19 are limited. This study will provide an integrated evaluation on the efficacy, safety, and immunogenicity of the COVID-19 vaccines.
Topics: Adolescent; Adult; Aged; Antibodies, Neutralizing; COVID-19; COVID-19 Vaccines; Humans; Immunogenicity, Vaccine; Injections, Intramuscular; Middle Aged; Pain; Randomized Controlled Trials as Topic; SARS-CoV-2; Young Adult
PubMed: 34707602
DOI: 10.3389/fimmu.2021.714170 -
Neurology Nov 2021There is accumulating evidence supporting an association between the thrombosis and thrombocytopenia syndrome (TTS) and adenovirus vector-based vaccines against severe... (Meta-Analysis)
Meta-Analysis
BACKGROUND AND OBJECTIVES
There is accumulating evidence supporting an association between the thrombosis and thrombocytopenia syndrome (TTS) and adenovirus vector-based vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Yet TTS and TTS-associated cerebral venous sinus thrombosis (CVST) remain poorly characterized. We aim to systematically evaluate the proportion of CVST among TTS cases and assess its characteristics and outcomes.
METHODS
We performed a systematic review and meta-analysis of clinical trials, cohorts, case series, and registry-based studies with the aim to assess (1) the pooled mortality rate of CVST, TTS-associated CVST, and TTS and (2) the pooled proportion of patients with CVST among patients with any thrombotic event and TTS. Secondary outcomes comprised clinical characteristics of patients with postvaccination thrombotic event. This meta-analysis is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was written according to the Meta-analysis of Observational Studies in Epidemiology proposal.
RESULTS
Sixty-nine studies were included in the qualitative analysis comprising 370 patients with CVST out of 4,182 patients with any thrombotic event associated with SARS-CoV-2 vector-based vaccine administration. Twenty-three studies were included further in quantitative meta-analysis. Among TTS cases, the pooled proportion of CVST was 51% (95% confidence interval [CI] 36%-66%; = 61%). TTS was independently associated with a higher likelihood of CVST when compared to patients without TTS with thrombotic events after vaccination (odds ratio 13.8; 95% CI 2.0-97.3; = 78%). The pooled mortality rates of TTS and TTS-associated CVST were 28% (95% CI 21%-36%) and 38% (95% CI 27%-49%), respectively. Thrombotic complications developed within 2 weeks of exposure to vector-based SARS-CoV-2 vaccines (mean interval 10 days; 95% CI 8-12) and affected predominantly women (69%; 95% CI 60%-77%) under age 45, even in the absence of prothrombotic risk factors.
DISCUSSION
Approximately half of patients with TTS present with CVST; almost one-third of patients with TTS do not survive. Further research is required to identify independent predictors of TTS following adenovirus vector-based vaccination.
REGISTRATION INFORMATION
The prespecified study protocol has been registered in the International Prospective Register of Ongoing Systematic Reviews PROSPERO (CRD42021250709).
Topics: COVID-19; COVID-19 Vaccines; Female; Humans; Middle Aged; SARS-CoV-2; Sinus Thrombosis, Intracranial; Thrombocytopenia; Thrombosis
PubMed: 34610990
DOI: 10.1212/WNL.0000000000012896 -
Infectious Disorders Drug Targets 2022Many potential vaccines for COVID-19 are being studied and developed. Several studies have reported on the safety and efficacy of these vaccines. This systematic review...
INTRODUCTION
Many potential vaccines for COVID-19 are being studied and developed. Several studies have reported on the safety and efficacy of these vaccines. This systematic review aimed to report on the current evidence concerning the feasibility and effectiveness of vaccines for COVID-19.
METHODS
A systematic search was carried out utilizing the keywords in the online databases, including Scopus, Web of Science, PubMed, Embase, and Cochrane. We included both human and non-human studies because of the vaccine novelty, limiting our ability to include sufficient human studies.
RESULTS
This review showed several SARS-CoV-2 vaccines to be currently under development using different platforms, including eight vaccines that are adenovirus-based vectors, six vaccines that are RNA-based formulations, one vaccine being DNA-based formulation, and other vaccines using other platforms, including lipid nanoparticles. Although the safety and efficacy profiles of these vaccines are still under debate, some countries have allowed for emergency use of some vaccines in at-risk populations, such as healthcare workers and the elderly.
CONCLUSION
It is crucial to gather as much clinically relevant evidence as possible regarding the immunogenicity, efficacy, and safety profiles of available vaccines and adhere wisely to CDC protocols and guidelines for vaccine production.
Topics: COVID-19; COVID-19 Vaccines; Feasibility Studies; Humans; Immunogenicity, Vaccine; Liposomes; Nanoparticles; SARS-CoV-2
PubMed: 34554905
DOI: 10.2174/1871526521666210923144837 -
Bulletin of the National Research Centre 2021High effectiveness of COVID-19 vaccines is essential for the pandemic control. This study systematically reviewed available evidence on effectiveness of ChAdOx1 and... (Review)
Review
BACKGROUND
High effectiveness of COVID-19 vaccines is essential for the pandemic control. This study systematically reviewed available evidence on effectiveness of ChAdOx1 and BNT162b2 vaccines in the general population, for improved vaccine policies and strategies.
MAIN BODY OF THE ABSTRACT
Using several keywords, a search of Scopus, PubMed, Google scholar and Hinari databases was conducted from December 1, 2020 to June 9, 2021. Eligible studies comprising original studies reporting effectiveness of the vaccines, were included following PRISMA guidelines. Individual studies were assessed for quality using National Heart, Lung and Blood Institute quality assessment tool. A total of 1766 titles were retrieved and 11 were included, out of which only 5 were peer-reviewed. Although data availability was limited, studies suggest equivalent effectiveness of BNT162b2 and ChAdOx1 COVID-19 vaccine against SARS-CoV-2 infection and COVID-19 related morbidity and mortality. Vaccine effectiveness increased steadily to about 35 days, with an enhanced effectiveness following the second dose.
SHORT CONCLUSION
BNT162 and ChAdOx1 vaccines were associated with equivalent and high effectiveness which increased with time and a second dose in the general population. This encourages continued practice of other preventive measures, particularly during the first week of vaccination, and reinforces the need for a second dose.
PubMed: 34456555
DOI: 10.1186/s42269-021-00607-w -
Journal of Advanced Pharmaceutical... 2021Search for an effective and safe vaccine to prevent transmission of current pandemic is an unmet need. This study reviews and compares the available early phase clinical... (Review)
Review
Search for an effective and safe vaccine to prevent transmission of current pandemic is an unmet need. This study reviews and compares the available early phase clinical data of vaccine candidates which have reached phase 3 of clinical development. The latest update of "DRAFT landscape of coronavirus (CoV) disease 2019 candidate vaccines (October 2, 2020)" released by the World Health Organization was accessed to identify the potential vaccine candidates. The full text articles (published and/or preprint) of data of early clinical trials of the selected vaccines were accessed from the links provided in the same document, PubMed and/or medRxiv.com. After extraction and synthesis, the data were critically evaluated for the study efficacy and safety outcomes. Of the total 193 candidate vaccines 10 were found to reach phase 3 of the clinical development. Nine of these were included in the evaluation process. In all of the included studies, immunogenicity and serious adverse events/local or systemic adverse events/laboratory parameters abnormality was considered as efficacy and safety outcomes respectively. Immunogenicity response with most of the vaccines was either higher than or similar to the respective controls except one (recombinant adenovirus type 26 COV2 [Ad26.COV2.S]) for which it was less than that in control. Overall adverse events (related and/or unrelated) were more with vaccines than those with respective control(s) in three studies, in other two, these were similar whereas in one study, the events were less in the vaccine group than in control group and in the rest, data described were descriptive only without any mention for the same for the control. In conclusion all studies showed immunogenic response to target protein of severe acute respiratory syndrome CoV-2 and which was higher than the respective control except for Ad26.CoV2.S. Many of the vaccines caused more adverse events than the controls, however most were mild and transient and/or manageable.
PubMed: 34345597
DOI: 10.4103/japtr.JAPTR_229_20