scholarly journals Estimates of Single Dose and Full Dose BNT162b2 Vaccine Effectiveness among USAF Academy cadets, 1 Mar - 1 May 2021

2021 ◽  
Author(s):  
Douglas P Wickert ◽  
Erin Almand ◽  
Christopher A Cullenbine ◽  
Odaro J Huckstep ◽  
Joseph Rohrer ◽  
...  
Keyword(s):  
Young Adults ◽  
Single Dose ◽  
Confidence Interval ◽  
Military Training ◽  
Vaccine Dose ◽  
Infection Risk ◽  
Vaccine Effectiveness ◽  
Training Environment ◽  
Fold Reduction ◽  
University Setting

Beginning in early March 2021 and continuing through May 2021, the USAF Academy began vaccinating cadets for protection against the SARS-CoV-2 virus with the BNT162b2 (Pfizer-BioNTech) mRNA vaccine. During this period, vaccination of the almost 4200 cadet population increased from 3% to 85% and prevalence of COVID-19 in the cadet population was constant at approximately 0.4% as indicated by weekly surveillance testing. In this study, vaccine effectiveness at preventing infection is estimated by comparing infection risk as a function of time since vaccination. A statistically significant four-fold reduction in infection risk was observed 14 days after the first vaccine dose and an eleven-fold reduction in infection risk was observed in fully vaccinated cadets. Overall, the Pfizer-BioNTech vaccine was 91% (95% confidence interval = 55-99%) effective at preventing infection in healthy young adults (17-26 years of age) in a university setting and military training environment.

scholarly journals Comparative single-dose mRNA and ChAdOx1 vaccine effectiveness against SARS-CoV-2, including early variants of concern: a test-negative design, British Columbia, Canada

2021 ◽  
Author(s):  
Danuta M Skowronski ◽  
Solmaz Setayeshgar ◽  
Macy Zou ◽  
Natalie Prystajecky ◽  
John R Tyson ◽  
...  
Keyword(s):  
British Columbia ◽  
Single Dose ◽  
Genetic Characterization ◽  
Infection Risk ◽  
Vaccine Effectiveness ◽  
Rt Pcr ◽  
Randomized Controlled ◽  
Specimen Collection ◽  
Dose Vaccine

Introduction: In randomized controlled trials, single-dose efficacy against SARS-CoV-2 illness exceeded 90% for mRNA vaccines (BNT162b2 and mRNA-1273), and 75% for ChAdOx1. In British Columbia (BC), Canada second doses were deferred up to 16 weeks and ChAdOx1 was only initially recommended for adults 55 years of age and older. We compared single-dose vaccine effectiveness (VE) during the spring 2021 wave in BC when Alpha and Gamma variants of concern (VOC) predominated. Methods: VE was estimated against infection and hospitalization by test-negative design: cases were RT-PCR test-positive for SARS-CoV-2 and controls were test-negative. Adults 50-69 years old with specimen collection between April 4 and May 22 (weeks 14-20) were included. Variant-specific VE was estimated between weeks 17-20 when genetic characterization of all case viruses was performed, primarily through whole genome sequencing. Results: VE analyses included 7,116 (10%) cases and 60,958 controls. Three-quarters of vaccinated participants received mRNA vaccine (60% BNT162b2, 15% mRNA-1273) and 25% received ChAdOx1. Half of genetically characterized viruses were Alpha, with 38% Gamma, 4% Delta and 8% non-VOCs. Single-dose VE against any infection was 75% (95%CI: 72-78) for BNT162b2, 82% (95%CI: 76-87) for mRNA-1273 and 61% (95%CI: 54-66) for ChAdOx1. VE against hospitalization was 83% (95%CI: 76-89), 85% (95%CI: 63-94) and 96% (95%CI: 86-99), respectively. VE against Alpha vs. Gamma infections did not differ among mRNA (78%;95%CI: 73-82 and 80%;95%CI: 74-85) or ChAdOx1 (66%;95%CI: 57-74 and 60%;95%CI: 48-69) recipients. Conclusions: A single dose of mRNA vaccine reduced the SARS-CoV-2 infection risk by at least 75%, including infections due to early VOC. Although effectiveness of a single dose of ChAdOx1 was lower at 60% against infection, just one dose of any vaccine reduced the hospitalization risk by more than 80%. In the context of constrained vaccine supplies, these findings have implications for global vaccine deployment to reduce the overall burden of infections and hospitalizations due to SARS-CoV-2.

scholarly journals Single-dose mRNA vaccine effectiveness against SARS-CoV-2 in healthcare workers extending 16 weeks post-vaccination: a test-negative design from Quebec, Canada

2021 ◽  
Author(s):  
Sara Carazo ◽  
Denis Talbot ◽  
Nicole Boulianne ◽  
Marc Brisson ◽  
Rodica Gilca ◽  
...  
Keyword(s):  
Single Dose ◽  
Healthcare Workers ◽  
Conditional Logistic Regression ◽  
Vaccine Dose ◽  
Vaccine Effectiveness ◽  
Primary Analysis ◽  
Post Vaccination ◽  
Illness Onset ◽  
Outcome Severity ◽  
Specimen Collection

Abstract Introduction In Canada, first and second doses of mRNA vaccines against SARS-CoV-2 were uniquely spaced 16 weeks apart, but the duration of single-dose protection remains uncertain. We estimated one- and two-dose mRNA vaccine effectiveness (VE) among healthcare workers (HCWs) in Quebec, Canada including protection against varying outcome severity, variants of concern (VOC), and the stability of single-dose protection out to 16 weeks post-vaccination. Methods A test-negative design compared vaccination among SARS-CoV-2 test-positive and weekly-matched (10:1), randomly-sampled, test-negative HCWs using linked surveillance and immunization databases. Vaccine status was defined by one dose ≥14 days or two doses ≥7 days before illness onset or specimen collection. Adjusted VE was estimated by conditional logistic regression. Results Primary analysis included 5,316 cases and 53,160 controls. Single-dose VE was 70% (95%CI: 68-73) against SARS-CoV-2 infection, 73% (95%CI: 71-75) against COVID-19 illness and 97% (95%CI: 92-99) against associated hospitalization. Two-dose VE was 86% (95%CI: 81-90) and 93% (95%CI: 89-95), respectively, with no associated hospitalizations. VE was higher for non-VOC than VOC (73% Alpha) among single-dose (77%, 95%CI: 73-81 versus 63%, 95%CI: 57-67) but not two-dose recipients (87%, 95%CI: 57-96 versus 94%, 95%CI: 89-96). Across 16 weeks, no decline in single-dose VE was observed with appropriate stratification based upon prioritized vaccination determined by higher versus lower likelihood of direct patient contact. Conclusion One mRNA vaccine dose provided substantial and sustained protection to HCWs extending at least four months post-vaccination. In circumstances of vaccine shortage, delaying the second dose may be a pertinent public health strategy to consider.

scholarly journals BNT162b2 vaccine effectiveness in preventing asymptomatic infection with SARS-CoV-2 virus: a nationwide historical cohort study

2021 ◽  
Author(s):  
Galia Zacay ◽  
David Shasha ◽  
Ronen Bareket ◽  
Itai Kadim ◽  
Fabienne Hershkowitz Sikron ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Health Maintenance Organization ◽  
Vaccine Dose ◽  
Asymptomatic Infection ◽  
Vaccine Effectiveness ◽  
Study Cohort ◽  
Infection Rates ◽  
Symptomatic Infection ◽  
Historical Cohort ◽  
Health Maintenance

Abstract Background There is strong evidence regarding the efficacy and effectiveness of BNT162b2 vaccine in preventing symptomatic infection with SARS-CoV-2 virus. There is a relative paucity of data regarding effectiveness in prevention of asymptomatic infection. Methods In this real-world observational study, we identified a sub-population of individuals in a large health maintenance organization who were repeatedly tested for SARS-CoV-2 infection by PCR. We included these individuals in the study cohort, and compared those who were vaccinated with BNT162b2 mRNA vaccine to the unvaccinated ones. A positive SARS-CoV-2 PCR test result was used as the outcome. Follow-up period was from January 1,2021 until February 11, 2021. Findings 6,286 individuals were included in the cohort. Seven days following the second vaccine dose, a rate of six positive PCR tests per 10,000 person-days was recorded, compared with a rate of 53 positive tests per 10,000 person-days for the unvaccinated group. The estimated vaccine effectiveness against infection with SARS-CoV-2 virus after two vaccine doses was 89% (95% confidence interval 82%-94%). The estimated effectiveness two weeks following the first vaccine dose was 61% (95% confidence interval 49%-71%). Interpretation In this study, vaccination with BNT162b2 reduced infection rates among individuals who underwent screening by frequent SARS-CoV-2 PCR testing. Using a cohort of frequently tested individuals reduced the indication bias for the PCR testing, which enabled estimation of infection rates. Funding This study received no funding.

scholarly journals Single-dose mRNA vaccine effectiveness against SARS-CoV-2 in healthcare workers extending 16 weeks post-vaccination: a test-negative design from Quebec, Canada

2021 ◽  
Author(s):  
Sara Carazo ◽  
Denis Talbot ◽  
Nicole Boulianne ◽  
Marc Brisson ◽  
Rodica Gilca ◽  
...  
Keyword(s):  
Single Dose ◽  
Healthcare Workers ◽  
Conditional Logistic Regression ◽  
Vaccine Dose ◽  
Vaccine Effectiveness ◽  
Primary Analysis ◽  
Post Vaccination ◽  
Illness Onset ◽  
Outcome Severity ◽  
Specimen Collection

Introduction: In Canada, first and second doses of mRNA vaccines against SARS-CoV-2 were uniquely spaced 16 weeks apart, but the duration of single-dose protection remains uncertain. We estimated one- and two-dose mRNA vaccine effectiveness (VE) among healthcare workers (HCWs) in Quebec, Canada including protection against varying outcome severity, variants of concern (VOC), and the stability of single-dose protection out to 16 weeks post-vaccination. Methods: A test-negative design compared vaccination among SARS-CoV-2 test-positive and weekly-matched (10:1), randomly-sampled, test-negative HCWs using linked surveillance and immunization databases. Vaccine status was defined by one dose ≥14 days or two doses ≥7 days before illness onset or specimen collection. Adjusted VE was estimated by conditional logistic regression. Results: Primary analysis included 5,316 cases and 53,160 controls. Single-dose VE was 70% (95%CI: 68-73) against SARS-CoV-2 infection, 73% (95%CI: 71-75) against COVID-19 illness and 97% (95%CI: 92-99) against associated hospitalization. Two-dose VE was 86% (95%CI: 81-90) and 93% (95%CI: 89-95), respectively, with no associated hospitalizations. VE was higher for non-VOC than VOC (73% Alpha) among single-dose (77%, 95%CI: 73-81 versus 63%, 95%CI: 57-67) but not two-dose recipients (87%, 95%CI: 57-96 versus 94%, 95%CI: 89-96). Across 16 weeks, no decline in single-dose VE was observed with appropriate stratification based upon prioritized vaccination determined by higher versus lower likelihood of direct patient contact. Conclusion: One mRNA vaccine dose provided substantial and sustained protection to HCWs extending at least four months post-vaccination. In circumstances of vaccine shortage, delaying the second dose may be a pertinent public health strategy to consider.

Resistance-guided treatment of Mycoplasma genitalium infection at a UK sexual health centre

2021 ◽  
pp. 095646242098776
Author(s):  
Ruairi JH Conway ◽  
Seamus Cook ◽  
Cassandra Malone ◽  
Simon Bone ◽  
Mohammed Osman Hassan-Ibrahim ◽  
...  
Keyword(s):  
Single Dose ◽  
Confidence Interval ◽  
Sexual Health ◽  
Treatment Failure ◽  
Inflammatory Disease ◽  
Health Centre ◽  
Mycoplasma Genitalium ◽  
Macrolide Resistance ◽  
Fluoroquinolone Resistance ◽  
Treatment Failure Rate

We evaluated the ResistancePlus® MG assay in providing macrolide resistance-guided treatment (RGT) for Mycoplasma genitalium infection at a UK sexual health centre. M. genitalium–positive samples from men with urethritis and women with pelvic inflammatory disease (PID) were tested for macrolide resistance–mediating mutations (MRMMs). MRMM-positive infections were given moxifloxacin 400 mg; otherwise 2 g azithromycin (1 g single dose and then 500 mg OD) was given. Among 57  M. genitalium–positive patients (32 men and 25 women), MRMMs were detected in 41/57 (72% [95% confidence interval (95% CI) 58–83%). Thirty-two of 43 patients given RGT attended for test of cure. Treatment failure rate was significantly lower at 1/32 (3%) than 10/37 (27%) before RGT ( n = 37 [men = 23 and women = 17]; p = 0.008). Treatment failure was lower in male urethritis (0/15 vs. 7/21 p = 0.027) but not in female PID. There was a trend of a shorter time to negative test of cure (TOC) in male urethritis (55.1 [95% 43.7–66.4] vs. 85.1 [95% CI CI 64.1–106.0] days, p = 0.077) but not in female PID. Macrolide resistance is higher than previous UK reports and higher than expected. RGT reduces overall treatment failure and is particularly beneficial in M. genitalium urethritis. Fluoroquinolone resistance will continue to rise with increasing fluoroquinolone use, and RGT is critical to direct appropriate azithromycin use and prevent overuse of moxifloxacin.

Vaccine effectiveness of Pfizer-BioNTech and Oxford-AstraZeneca to prevent severe COVID-19 in Costa Rica: A nationwide, observational study of hospitalizations prevalence (Preprint)

2021 ◽  
Author(s):  
Luis Rosero-Bixby
Keyword(s):  
Single Dose ◽  
Costa Rica ◽  
Observational Study ◽  
Real World ◽  
Vaccine Coverage ◽  
Secondary Analysis ◽  
Vaccine Effectiveness ◽  
Costa Rican ◽  
Vaccination Program ◽  
Severe Illness

BACKGROUND The Costa Rican vaccination program uses Pfizer-BioNTech and Oxford-AstraZeneca vaccines. Real-world estimates of these vaccines effectiveness to prevent hospitalizations range from 90% to 98% for two doses and from 70% to 91% for a single dose. Almost all of these estimates predate the Delta variant. OBJECTIVE To estimate the dose-dependent effectiveness of coronavirus disease (COVID-19) vaccines to prevent severe illness in real-world conditions of Costa Rica, after the Delta variant became dominant. METHODS This observational study is a secondary analysis of hospitalizations prevalence. The participants are all 3.67 million adults residents in Costa Rica by mid-2021. The study is based on public aggregated data of 5978 COVID-19-related hospital records from 14th September to 20th October, 2021 and 6.1 million vaccination doses administered to determine hospitalization prevalence by dose-specific vaccination status. The intervention retrospectively evaluated is vaccination with Pfizer-BioNTech (78%) and Oxford-AstraZeneca (22%). The main outcome studied is being hospitalized. RESULTS Vaccine effectiveness to prevent hospitalization (VEH) was estimated as 93.4% (95% confidence interval [CI]: 93.0 to 93.9) for complete vaccination and 76.7% (CI: 75.0 to 78.3) for single-dose vaccination among adults of all ages. VEH was lower and more uncertain among older adults aged 58 years and above: 92% (CI: 91% to 93%) for those who had received full vaccination and 64% (CI: 58% to 69%) for those who had received partial vaccination. Single-dose VEH declined over time during the study period, especially in the older age group. Estimates were sensitive to possible errors in the population count used to determine the residual number of unvaccinated people when vaccine coverage is high. CONCLUSIONS The Costa Rican vaccination program that administered Pfizer and Oxford vaccines are highly effective to prevent COVID-19-related hospitalizations after the Delta variant had become dominant. Moreover, a single dose is reasonably effective, justifying the continuation of the national policy of postponing the application for the second dose of the Pfizer vaccine to accelerate the vaccination and increase the number of people being vaccinated. Timely monitoring of vaccine effectiveness is important to detect eventual failures and motivate the public based on information that the vaccinations are effective.

scholarly journals Measles Outbreak Associated With Low Vaccine Effectiveness Among Adults in Pohnpei State, Federated States of Micronesia, 2014

2016 ◽  
Vol 3 (2) ◽  
Author(s):  
Craig M. Hales ◽  
Eliaser Johnson ◽  
Louisa Helgenberger ◽  
Mark J. Papania ◽  
Maribeth Larzelere ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Vaccination Campaign ◽  
Vaccine Effectiveness ◽  
Mass Vaccination ◽  
Cold Chain ◽  
Primary Case ◽  
Federated States Of Micronesia ◽  
Measles Outbreak ◽  
Mass Vaccination Campaign ◽  
Vaccination Campaigns

Abstract Background.  A measles outbreak in Pohnpei State, Federated States of Micronesia in 2014 affected many persons who had received ≥1 dose of measles-containing vaccine (MCV). A mass vaccination campaign targeted persons aged 6 months to 49 years, regardless of prior vaccination. Methods.  We evaluated vaccine effectiveness (VE) of MCV by comparing secondary attack rates among vaccinated and unvaccinated contacts after household exposure to measles. Results.  Among 318 contacts, VE for precampaign MCV was 23.1% (95% confidence interval [CI], −425 to 87.3) for 1 dose, 63.4% (95% CI, −103 to 90.6) for 2 doses, and 95.9% (95% CI, 45.0 to 100) for 3 doses. Vaccine effectiveness was 78.7% (95% CI, 10.1 to 97.7) for campaign doses received ≥5 days before rash onset in the primary case and 50.4% (95% CI, −52.1 to 87.9) for doses received 4 days before to 3 days after rash onset in the primary case. Vaccine effectiveness for most recent doses received before 2010 ranged from 51% to 57%, but it increased to 84% for second doses received in 2010 or later. Conclusions.  Low VE was a major source of measles susceptibility in this outbreak; potential reasons include historical cold chain inadequacies or waning of immunity. Vaccine effectiveness of campaign doses supports rapid implementation of vaccination campaigns in outbreak settings.

scholarly journals Interim estimates of 2015/16 vaccine effectiveness against influenza A(H1N1)pdm09, Canada, February 2016

2016 ◽  
Vol 21 (11) ◽  
Author(s):  
Catharine Chambers ◽  
Danuta M Skowronski ◽  
Suzana Sabaiduc ◽  
Anne Luise Winter ◽  
James A Dickinson ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Northern Hemisphere ◽  
Influenza A ◽  
Vaccine Effectiveness ◽  
Genetic Evolution ◽  
Significant Protection ◽  
Surveillance Network ◽  
Potential Gain ◽  
Influenza A H1n1

Using a test-negative design, the Canadian Sentinel Practitioner Surveillance Network (SPSN) assessed interim 2015/16 vaccine effectiveness (VE) against influenza A(H1N1)pdm09 viruses. Adjusted VE showed significant protection of 64% (95% confidence interval (CI): 44–77%) overall and 56% (95%CI: 26–73%) for adults between 20 and 64 years-old against medically attended, laboratory-confirmed A(H1N1)pdm09 illness. Among the 67 A(H1N1)pdm09-positive specimens that were successfully sequenced, 62 (> 90%) belonged to the emerging genetic 6B.1 subclade, defined by S162N (potential gain of glycosylation) and I216T mutations in the haemagglutinin protein. Findings from the Canadian SPSN indicate that the 2015/16 northern hemisphere vaccine provided significant protection against A(H1N1)pdm09 illness despite genetic evolution in circulating viruses.

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