CRIS

Permanent URI for this communityhttps://investigadores.udd.cl/handle/123456789/1

Browse

Search Results

Now showing 1 - 10 of 13

Some of the metrics are blocked by your
consent settings
Immunogenicity of the 9-valent human papillomavirus vaccine: Post hoc analysis from five phase 3 studies
(Informa UK Limited, 2025-01-22)
Anna R. Giuliano
;
Joel M. Palefsky
;
Stephen E. Goldstone
;
Jacob Bornstein
;
Ilse De Coster
Scopus© Citations 8 2
Some of the metrics are blocked by your
consent settings
Mutation in a SARS-CoV-2 Haplotype from Sub-Antarctic Chile Reveals New Insights into the Spike’s Dynamics
(2021)
Jorge González-Puelma
;
Jacqueline Aldridge
;
Marco Montes de Oca
;
Mónica Pinto
;
Roberto Uribe-Paredes
<jats:p>The emergence of SARS-CoV-2 variants, as observed with the D614G spike protein mutant and, more recently, with B.1.1.7 (501Y.V1), B.1.351 (501Y.V2) and B.1.1.28.1 (P.1) lineages, represent a continuous threat and might lead to strains of higher infectivity and/or virulence. We report on the occurrence of a SARS-CoV-2 haplotype with nine mutations including D614G/T307I double-mutation of the spike. This variant expanded and completely replaced previous lineages within a short period in the subantarctic Magallanes Region, southern Chile. The rapid lineage shift was accompanied by a significant increase of cases, resulting in one of the highest incidence rates worldwide. Comparative coarse-grained molecular dynamic simulations indicated that T307I and D614G belong to a previously unrecognized dynamic domain, interfering with the mobility of the receptor binding domain of the spike. The T307I mutation showed a synergistic effect with the D614G. Continuous surveillance of new mutations and molecular analyses of such variations are important tools to understand the molecular mechanisms defining infectivity and virulence of current and future SARS-CoV-2 strains.</jats:p>
1Scopus© Citations 9
Some of the metrics are blocked by your
consent settings
Seroprevalence of Natural and Acquired Immunity against the SARS-CoV-2 Virus in a Population Cohort from Two Chilean Cities, 2020–2022
(2023)
Loreto Núñez-Franz
;
Muriel Ramírez-Santana
;
RUBILAR RAMIREZ, PAOLA
;
Macarena Said
;
VIAL COX, MARIA CECILIA
<jats:p>Background: Chile has achieved the highest coverage for vaccines against the SARS-CoV-2 virus worldwide. Objective: To assess the progression of immunity (natural and acquired by vaccine) in a cohort from two Chilean cities. Methods: Individuals (n = 386) who participated in three phases of population-based serial prevalence studies were included (2020–2021 and 2022). Presence of SARS-CoV-2 antibodies was measured in serum. Data including time of vaccination and type of vaccine received were analysed with descriptive statistics. Results: Seroprevalence was 3.6% in the first round and increased to 96.9% in the second and 98.7% in the third. In the third round, 75% of individuals who had received the basal full scheme were seropositive at 180 days or more since their last dose; 98% of individuals who received one booster dose were seropositive at 180 days or more, and 100% participants who received two boosters were seropositive, regardless of time since their last dose. Participants receiving mRNA vaccines had higher seroprevalence rates over time. Conclusions: The high vaccination coverage in Chile enabled the population to maintain high levels of antibodies. Vaccination boosters are essential to maintain immunity over time, which also depends on the type of vaccine administered.</jats:p>
1Scopus© Citations 12
Some of the metrics are blocked by your
consent settings
Neutralizing antibodies induced by homologous and heterologous boosters in CoronaVac vaccines in Chile
(2023)
ACEVEDO ROMO, JOHANNA PATRICIA
;
Mónica L. Acevedo
;
Aracelly Gaete-Argel
;
ARAOS BRALIC, RAFAEL IGNACIO
;
Cecilia Gonzalez
Scopus© Citations 4 21
Some of the metrics are blocked by your
consent settings
Three-Year Follow-up of 2-Dose Versus 3-Dose HPV Vaccine
(2021)
Jacob Bornstein
;
Surita Roux
;
Lone Kjeld Petersen
;
Li-Min Huang
;
Simon R. Dobson
<jats:sec> <jats:title /> </jats:sec> <jats:sec> <jats:title>BACKGROUND AND OBJECTIVES:</jats:title> <jats:p>Human papillomavirus (HPV) antibody responses to the 9-valent human papillomavirus (9vHPV) vaccine among girls and boys (aged 9–14 years) receiving 2-dose regimens (months 0, 6 or 0, 12) were noninferior to a 3-dose regimen (months 0, 2, 6) in young women (aged 16–26 years) 4 weeks after last vaccination in an international, randomized, open-label trial (NCT01984697). We assessed response durability through month 36.</jats:p> </jats:sec> <jats:sec> <jats:title>METHODS:</jats:title> <jats:p>Girls received 2 (months 0 and 6 [0, 6]: n = 301; months 0 and 12 [0, 12]: n = 151) or 3 doses (months 0,2, and 6 [0, 2, 6]: n = 301); boys received 2 doses ([0, 6]: n = 301; [0, 12]: n = 150); and young women received 3 doses ([0, 2, 6]: n = 314) of 9vHPV vaccine. Anti-HPV geometric mean titers (GMTs) were assessed by competitive Luminex immunoassay (cLIA) and immunoglobulin G-Luminex immunoassay (IgG-LIA) through month 36.</jats:p> </jats:sec> <jats:sec> <jats:title>RESULTS:</jats:title> <jats:p>Anti-HPV GMTs were highest 1 month after the last 9vHPV vaccine regimen dose, decreased sharply during the subsequent 12 months, and then decreased more slowly. GMTs 2 to 2.5 years after the last regimen dose in girls and boys given 2 doses were generally similar to or greater than GMTs in young women given 3 doses. Across HPV types, most boys and girls who received 2 doses (cLIA: 81%–100%; IgG-LIA: 91%–100%) and young women who received 3 doses (cLIA: 78%–98%; IgG-LIA: 91%–100%) remained seropositive 2 to 2.5 years after the last regimen dose.</jats:p> </jats:sec> <jats:sec> <jats:title>CONCLUSIONS:</jats:title> <jats:p>Antibody responses persisted through 2 to 2.5 years after the last dose of a 2-dose 9vHPV vaccine regimen in girls and boys. In girls and boys, antibody responses generated by 2 doses administered 6 to 12 months apart may be sufficient to induce high-level protective efficacy through at least 2 years after the second dose.</jats:p> </jats:sec>
13 1Scopus© Citations 18
Some of the metrics are blocked by your
consent settings
Longitudinal assessment of SARS-CoV-2 IgG seroconversionamong front-line healthcare workers during the first wave of the Covid-19 pandemic at a tertiary-care hospital in Chile
(2021)
IRURETAGOYENA BRUCE, MIRENTXU INES
;
Macarena R. Vial
;
Maria Spencer-Sandino
;
Pablo Gaete
;
Anne Peters
<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background</jats:title> <jats:p>Healthcare workers (HCWs) are at high risk of exposure to SARS-CoV-2. Cross-sectional studies have provided variable rates of seroprevalence in HCWs. Longitudinal assessments of the serological response to Covid-19 among HCWs are crucial to understanding the risk of infection and changes in antibody titers over time. We aimed to investigate seroprevalence and risk factors associated with seroconversion in a prospective cohort of HCWs during the peak of the first wave of the Covid-19 pandemic.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>We conducted a longitudinal study among 446 front-line HCWsin a tertiary-care hospital in Chile from April to July 2020. IgG was determined monthly using two different ELISAs in serum samples of HCWs, during the three-month period. In each visit, demographic data, symptoms, risk factors, and exposure risks were also assessed.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>The overall seroprevalence at the end of the study period was 24% (95% CI20.2–28.3), with 43% of seropositive HCWs reporting no prior symptoms. Seroconversion rates significantly differed over the study period, from 2.1% to as high as 8.8% at the peak of the epidemic. There were no statistically significant differences observed between HCWs in direct clinical care of patients with Covid-19 and those working in low risk areas. Antibody titers appeared to wane over time.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>HCWs were severely affected with a high rate of seroconversion that appeared to mirror the local epidemiological situation. A significant amount of participants underwent an asymptomatic infection, highlighting the need for improved surveillance policies. Antibody titers appear to wane over time; further studies to understand this finding’s impact on the risk of reinfection are warranted.</jats:p> </jats:sec>
1Scopus© Citations 21 2
Some of the metrics are blocked by your
consent settings
Safety and Immunogenicity of an Inactivated Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine in a Subgroup of Healthy Adults in Chile
(2021)
Susan M Bueno
;
Katia Abarca
;
GONZALEZ, PABLO
;
Nicolás M S Gálvez
;
Jorge A Soto
<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>The development of effective vaccines against coronavirus disease 2019 is a global priority. CoronaVac is an inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine with promising safety and immunogenicity profiles. This article reports safety and immunogenicity results obtained for healthy Chilean adults aged ≥18 years in a phase 3 clinical trial.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Volunteers randomly received 2 doses of CoronaVac or placebo, separated by 2 weeks. A total of 434 volunteers were enrolled, 397 aged 18–59 years and 37 aged ≥60 years. Solicited and unsolicited adverse reactions were registered from all volunteers. Blood samples were obtained from a subset of volunteers and analyzed for humoral and cellular measures of immunogenicity.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>The primary adverse reaction in the 434 volunteers was pain at the injection site, with a higher incidence in the vaccine than in the placebo arm. Adverse reactions observed were mostly mild and local. No severe adverse events were reported. The humoral evaluation was performed on 81 volunteers. Seroconversion rates for specific anti-S1-receptor binding domain (RBD) immunoglobulin G (IgG) were 82.22% and 84.44% in the 18–59 year age group and 62.69% and 70.37% in the ≥60 year age group, 2 and 4 weeks after the second dose, respectively. A significant increase in circulating neutralizing antibodies was detected 2 and 4 weeks after the second dose. The cellular evaluation was performed on 47 volunteers. We detected a significant induction of T-cell responses characterized by the secretion of interferon-γ (IFN-γ) upon stimulation with Mega Pools of peptides from SARS-CoV-2.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Immunization with CoronaVac in a 0–14 schedule in Chilean adults aged ≥18 years is safe, induces anti-S1-RBD IgG with neutralizing capacity, activates T cells, and promotes the secretion of IFN-γ upon stimulation with SARS-CoV-2 antigens.</jats:p> </jats:sec>
Scopus© Citations 75 1
Some of the metrics are blocked by your
consent settings
Inactivated Vaccine-Induced SARS-CoV-2 Variant-Specific Immunity in Children
(2022)
Jorge A. Soto
;
Felipe Melo-González
;
Cristián Gutierrez-Vera
;
Bárbara M. Schultz
;
Roslye V. Berríos-Rojas
<jats:p>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.</jats:p>
1Scopus© Citations 20 16
Some of the metrics are blocked by your
consent settings
Serological study of CoronaVac vaccine and booster doses in Chile: immunogenicity and persistence of anti-SARS-CoV-2 spike antibodies
(2022)
Leonardo Vargas
;
Nicolás Valdivieso
;
Fabián Tempio
;
Valeska Simon
;
Daniela Sauma
<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background</jats:title> <jats:p>Chile was severely affected by COVID19 outbreaks but was also one of the first countries to start a nationwide program to vaccinate against the disease. Furthermore, Chile became one of the fastest countries to inoculate a high percentage of the target population and implemented homologous and heterologous booster schemes in late 2021 to prevent potential immunological waning. The aim of this study is to compare the immunogenicity and time course of the humoral response elicited by the CoronaVac vaccine in combination with homologous versus heterologous boosters.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>We compared the immunogenicity of two doses of CoronaVac and BNT162b2 vaccines and one homologous or heterologous booster through an ELISA assay directed against the ancestral spike protein of SARS-CoV-2. Sera were collected from individuals during the vaccination schedule and throughout the implementation of homologous and heterologous booster programs in Chile.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Our findings demonstrate that a two-dose vaccination scheme with CoronaVac induces lower levels of anti-SARS-CoV-2 spike antibodies than BNT162b2 in a broad age range (median age 42 years; interquartile range (IQR) 27-61). Furthermore, antibody production declines with time in individuals vaccinated with CoronaVac and less noticeably, with BNT162b2. Analysis of booster schemes revealed that individuals vaccinated with two doses of CoronaVac generate immunological memory against the SARS-CoV-2 ancestral strain, which can be re-activated with homologous or heterologous (BNT162b2 and ChAdOx1) boosters. Nevertheless, the magnitude of the antibody response with the heterologous booster regime was considerably higher (induction fold BNT162b2: 11.2x; ChAdoX1; 12.4x; CoronaVac: 6.0x) than the responses induced by the homologous scheme. Both homologous and heterologous boosters induced persistent humoral responses (median 122 days, IQR (108-133)), although heterologous boosters remained superior in activating a humoral response after 100 days.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Two doses of CoronaVac induces antibody titers against the SARS-CoV-2 ancestral strain which are lower in magnitude than those induced by the BNT162b2 vaccine. However, the response induced by CoronaVac can be greatly potentiated with a heterologous booster scheme with BNT162b2 or ChAdOx1 vaccines. Furthermore, the heterologous and homologous booster regimes induce a durable antibody response which does not show signs of decay 3 months after the booster dose.</jats:p> </jats:sec>
Scopus© Citations 14 1
Some of the metrics are blocked by your
consent settings
Evaluation of the Immune Response Induced by CoronaVac 28-Day Schedule Vaccination in a Healthy Population Group
(2022)
Alejandro Escobar
;
Felipe E. Reyes-López
;
Mónica L. Acevedo
;
Luis Alonso-Palomares
;
Fernando Valiente-Echeverría
<jats:p>CoronaVac vaccine from Sinovac Life Science is currently being used in several countries. In Chile, the effectiveness of preventing hospitalization is higher than 80% with a vaccination schedule. However, to date, there are no data about immune response induction or specific memory. For this reason, we recruited 15 volunteers without previous suspected/diagnosed COVID-19 and with negative PCR over time to evaluate the immune response to CoronaVac 28 and 90 days after the second immunization (dpi). The CoronaVac administration induces total and neutralizing anti-spike antibodies in all vaccinated volunteers at 28 and 90 dpi. Furthermore, using ELISpot analysis to assay cellular immune responses against SARS-CoV-2 spike protein, we found an increase in IFN-gamma- and Granzyme B-producing cells in vaccinated volunteers at 28 and 90 dpi. Together, our results indicate that CoronaVac induces a robust humoral immune response and cellular immune memory of at least 90 dpi.</jats:p>
23Scopus© Citations 19

CRIS

Browse

Filters

Settings

Sort By

Results per page

Search Results