Effect of Vaccination on Transmission of SARS-CoV-2.
Ontology highlight
ABSTRACT:
SUBMITTER: Shah ASV
PROVIDER: S-EPMC8451182 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description: Not available
| S-EPMC8262621 | biostudies-literature
Project description:Effective vaccines protect individuals by not only reducing the susceptibility to infection, but also reducing the infectiousness of breakthrough infections in vaccinated cases. To disentangle the vaccine effectiveness against susceptibility to infection (VES) and vaccine effectiveness against infectiousness (VEI), we took advantage of Danish national data comprising 24,693 households with a primary case of SARS-CoV-2 infection (Delta Variant of Concern, 2021) including 53,584 household contacts. In this setting, we estimated VES as 61% (95%-CI: 59-63), when the primary case was unvaccinated, and VEI as 31% (95%-CI: 26-36), when the household contact was unvaccinated. Furthermore, unvaccinated secondary cases with an infection exhibited a three-fold higher viral load compared to fully vaccinated secondary cases with a breakthrough infection. Our results demonstrate that vaccinations reduce susceptibility to infection as well as infectiousness, which should be considered by policy makers when seeking to understand the public health impact of vaccination against transmission of SARS-CoV-2.
| S-EPMC9244879 | biostudies-literature
Project description:Hereby, we report a confirmed case of intrauterine SARS-CoV-2 transmission with rapid placental dysfunction and fetal distress.
| PRJEB40434 | ENA
Project description:A single SARS-CoV-2 vaccine dose reduces onward transmission from case-patients. We assessed the potential effects of receiving 2 doses on household transmission for case-patients in England and their household contacts. We used stratified Cox regression models to calculate hazard ratios (HRs) for contacts becoming secondary case-patients, comparing contacts of 2-dose vaccinated and unvaccinated index case-patients. We controlled for age, sex, and vaccination status of case-patients and contacts, as well as region, household composition, and relative socioeconomic condition based on household location. During the Alpha-dominant period, HRs were 0.19 (0.13-0.28) for contacts of 2-dose BNT162b2-vaccinated case-patients and 0.54 (0.41-0.69) for contacts of 2-dose Ch4dOx1-vaccinated case-patients; during the Delta-dominant period, HRs were higher, 0.74 (0.72-0.76) for BNT162b2 and 1.06 (1.04-1.08) for Ch4dOx1. Reduction of onward transmission was lower for index case-patients who tested positive ≥2 months after the second dose of either vaccine.
| S-EPMC9796187 | biostudies-literature
Project description:BackgroundCOVID-19 vaccination was expected to reduce SARS-CoV-2 transmission, but the relevance of this effect remains unclear. We aimed to estimate the effectiveness of COVID-19 vaccination of the index cases and their close contacts in reducing the probability of SARS-CoV-2 transmission.MethodsTransmission of SARS-CoV-2 infection was evaluated in two cohorts of adult close contacts of COVID-19 confirmed cases (social and household settings) by COVID-19 vaccination status of the index case and the close contact, from April to November 2021 in Navarre, Spain. The effects of vaccination of the index case and the close contact were estimated as (1-adjusted relative risk) × 100%.ResultsAmong 19,631 social contacts, 3257 (17%) were confirmed with SARS-CoV-2. COVID-19 vaccination of the index case reduced infectiousness by 44% (95% CI, 27-57%), vaccination of the close contact reduced susceptibility by 69% (95% CI, 65-73%), and vaccination of both reduced transmissibility by 74% (95% CI, 70-78%) in social settings, suggesting some synergy of effects. Among 20,708 household contacts, 6269 (30%) were infected, and vaccine effectiveness estimates were 13% (95% CI, -5% to 28%), 61% (95% CI, 58-64%), and 52% (95% CI, 47-56%), respectively. These estimates were lower in older people and had not relevant differences between the Alpha (April-June) and Delta (July-November) variant periods.ConclusionsCOVID-19 vaccination reduces infectiousness and susceptibility; however, these effects are insufficient for complete control of SARS-CoV-2 transmission, especially in older people and household setting. Relaxation of preventive behaviors after vaccination may counteract part of the vaccine effect on transmission.
| S-EPMC9876028 | biostudies-literature
Project description:Background Adults undergoing heart surgery are particularly vulnerable to respiratory complications, including COVID-19. Immunization can significantly reduce this risk; however, the effect of cardiopulmonary bypass (CPB) on immunization status is unknown. We sought to evaluate the effect of CPB on COVID-19 vaccination antibody concentration after cardiac surgery. Methods and Results This prospective observational clinical trial evaluated adult participants undergoing cardiac surgery requiring CPB at a single institution. All participants received a full primary COVID-19 vaccination series before CPB. SARS-CoV-2 spike protein-specific antibody concentrations were measured before CPB (pre-CPB measurement), 24 hours following CPB (postoperative day 1 measurement), and approximately 1 month following their procedure. Relationships between demographic or surgical variables and change in antibody concentration were assessed via linear regression. A total of 77 participants were enrolled in the study and underwent surgery. Among all participants, mean antibody concentration was significantly decreased on postoperative day 1, relative to pre-CPB levels (-2091 AU/mL, P<0.001). Antibody concentration increased between postoperative day 1and 1 month post CPB measurement (2465 AU/mL, P=0.015). Importantly, no significant difference was observed between pre-CPB and 1 month post CPB concentrations (P=0.983). Two participants (2.63%) developed symptomatic COVID-19 pneumonia postoperatively; 1 case of postoperative COVID-19 pneumonia resulted in mortality (1.3%). Conclusions COVID-19 vaccine antibody concentrations were significantly reduced in the short-term following CPB but returned to pre-CPB levels within 1 month. One case of postoperative COVID 19 pneumonia-specific mortality was observed. These findings suggest the need for heightened precautions in the perioperative period for cardiac surgery patients.
| S-EPMC10547352 | biostudies-literature
Project description:We studied the impact of a vaccine prime dose on CD8 T cell gene expression We first immunized mice with an Ad5-SARS CoV-2 spike vaccine and then evaluated gene expression on SARS CoV-2 specific CD8 T cells at week 4.
2021-08-11 | GSE173567 | GEO
Project description:The individual-level effectiveness of vaccines against clinical disease caused by SARS-CoV-2 is well-established. However, few studies have directly examined the effect of COVID-19 vaccines on transmission. We quantified the effectiveness of vaccination with BNT162b2 (Pfizer-BioNTech mRNA-based vaccine) against household transmission of SARS-CoV-2 in Israel. We fit two time-to-event models - a mechanistic transmission model and a regression model - to estimate vaccine effectiveness against susceptibility to infection and infectiousness given infection in household settings. Vaccine effectiveness against susceptibility to infection was 80-88%. For breakthrough infections among vaccinated individuals, the vaccine effectiveness against infectiousness was 41-79%. The overall vaccine effectiveness against transmission was 88.5%. Vaccination provides substantial protection against susceptibility to infection and slightly lower protection against infectiousness given infection, thereby reducing transmission of SARS-CoV-2 to household contacts.One-sentence summaryVaccination reduced both the rate of infection with SARS-CoV-2 and transmission to household contacts in Israel.
| S-EPMC8722617 | biostudies-literature
Project description:The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began proliferating widely throughout the world in late 2019/early 2020, creating a global pandemic and health crisis. Although vaccines became available to the public approximately one year after the onset of the pandemic, there still remains much hesitancy surrounding vaccination even two years into the pandemic. One key concern comes from reports of breakthrough infections among the vaccinated that show comparable levels of peak viral load as the unvaccinated, calling into question the ability of vaccines to slow or prevent transmission. Therefore young, healthy individuals who are at low risk of serious complications themselves have little incentive to receive a vaccine that they are not convinced will protect others around them. To address this important concern, this article analyzes COVID-19 incidence in the United States as a function of each state's vaccination rate. Results show that states with higher percentages of fully vaccinated individuals report fewer new cases among the remaining unvaccinated population. These data add to accumulating evidence that COVID-19 vaccinations can indeed slow the spread of SARS-CoV-2, and are an important tool in society's arsenal to put this pandemic behind us.
| S-EPMC8609904 | biostudies-literature
Project description:PurposeThe severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began proliferating widely throughout the world in late 2019/early 2020, creating a global pandemic and health crisis. Although vaccines became available to the public approximately 1 year after the onset of the pandemic, there still remains much hesitancy surrounding vaccination. One key concern comes from reports of breakthrough infections among the vaccinated that show comparable levels of peak viral load as the unvaccinated, calling into question the ability of vaccines to prevent transmission. Therefore young, healthy individuals who are at low risk of serious complications themselves have little incentive to receive a vaccine that they are not convinced will protect others around them. To address this important concern, this study aimed to evaluate the extent to which vaccination rates are associated with reduced SARS-CoV-2 transmission among the unvaccinated population.MethodsAn observational study was conducted in the United States of America throughout the months of June through September, 2021. Vaccination rate and incidence of coronavirus disease 2019 (COVID-19) were obtained for each state, along with a number of important control variables. Panel data regression was used to predict incidence among the unvaccinated based on each state's vaccination rate.ResultsStates with a higher proportion of fully vaccinated individuals reported fewer new cases among the remaining unvaccinated population.ConclusionThese data add to accumulating evidence that COVID-19 vaccinations can indeed slow the spread of SARS-CoV-2, and are an important tool in society's arsenal to put this pandemic behind us.
| S-EPMC8938221 | biostudies-literature