scholarly journals An outbreak caused by the SARS-CoV-2 Delta (B.1.617.2) variant in a care home after partial vaccination with a single dose of the COVID-19 vaccine Vaxzevria, London, England, April 2021

2021 ◽  
Vol 26 (27) ◽  
Author(s):  
Sarah V Williams ◽  
Amoolya Vusirikala ◽  
Shamez N Ladhani ◽  
Elena Fernandez Ruiz De Olano ◽  
Nalini Iyanger ◽  
...  
Keyword(s):  
Single Dose ◽  
Attack Rate ◽  
Care Home ◽  
Vaccine Dose

We investigated a COVID-19 outbreak of the SARS-CoV-2 Delta variant of concern in a London care home, where 8/21 residents and 14/21 staff had received a single dose of Vaxzevria (ChAdOx1-S; AstraZeneca) vaccine. We identified 24 SARS-CoV-2 infections (16 residents, 8 staff) among 40 individuals (19 residents, 21 staff); four (3 residents, 1 staff) were hospitalised, and none died. The attack rate after one vaccine dose was 35.7% (5/14) for staff and 81.3% (13/16) for residents.

scholarly journals Safety and Humoral Responses to SARS-CoV-2 mRNA Vaccination of Previously Infected and Naive Populations

2021 ◽  
Author(s):  
Shai Efrati ◽  
Merav Catalogna ◽  
Ramzia Abu Hamed ◽  
Amir Hadanny ◽  
Adina Bar-Chaim ◽  
...  
Keyword(s):  
Single Dose ◽  
Vaccine Dose ◽  
Medical Attention ◽  
Evaluation Procedure ◽  
Short Term ◽  
Serological Tests ◽  
Safety Issues ◽  
Infected Population ◽  
Group A ◽  
Humoral Responses

Abstract Since COVID-19 risk of reinfection is of great concern, the safety and efficacy of the mRNA-based vaccines in previously infected populations should be assessed. We studied 78 individuals previously infected with SARS-CoV-19, who received a single dose of BNT162b2 mRNA COVID-19 vaccine, and 1:2 ratio matched infection-naïve cohort who received two injections. The evaluation procedure included symptom monitoring, and serological tests. Among the post-infected population, the median IgG-S response after the first vaccine dose was 2260 AU/ml, compared to 238 AU/ml after the second vaccine injection in the infection naive group. A strong correlation was demonstrated between IgG-S level before vaccination, and the corresponding responses after a single vaccine dose (r = 0.8, p < 0.001) in the post infected population. Short-term severe symptoms that required medical attention were found in 6.8% among the post-infected individuals, while none were found in the infection naïve population. Our data suggest that a single vaccine dose is sufficient to induce an intense immune response in post-infected population regardless of seropositivity. Although some short-term safety issues were observed compared to the infection naïve population, a single dose regimen can be considered safe in post-infected populations.

scholarly journals Mapping of safe and early chemo-attenuated live Plasmodium falciparum immunization identifies immune signature of vaccine efficacy

2020 ◽  
Author(s):  
Steffen Borrmann ◽  
Zita Sulyok ◽  
Katja Müller ◽  
Mihaly Sulyok ◽  
Rolf Fendel ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Single Dose ◽  
Vaccine Efficacy ◽  
Human Subjects ◽  
Vaccine Dose ◽  
Effector Memory ◽  
Liver Stage ◽  
Rodent Malaria ◽  
Immune Signatures ◽  
Malaria Model

AbstractPotent protection against malaria can be induced by attenuated live-immunization with Plasmodium falciparum (Pf) sporozoites (SPZ). However, a better understanding of the critical processes involved in the establishment of protective immunity is needed. We explored the safety and vaccine efficacy of early chemo-attenuation of PfSPZ under atovaquone-proguanil (AP). AP caused early arrest of P. berghei liver stages. Despite the absence of replication, robust protection in mice correlated with parasite-specific effector-memory CD8+ T-cell responses. In a phase I clinical trial a single dose of AP prevented Pf infections in the liver of adult, human subjects who received three doses of 5.12×104 or 1.5×105 PfSPZ by direct venous inoculation combined with oral AP. However, only 2 of 8 (25%) and 2 of 10 (20%), respectively, were protected against controlled human malaria infection (CHMI) 10 weeks after the last vaccine dose, despite levels of IgG antibodies to the Pf circumsporozoite protein (PfCSP) comparable to those achieved in fully protected volunteers after immunization with 5.12×104 PfSPZ with chloroquine chemoprophylaxis active only against subsequent blood stages. We identify lower IgG recognition of the secreted liver stage-specific antigens LISP2 and LSA1 and the multi-stage antigen MSP5 as immune signatures of inferior vaccine efficacy compared to PfSPZ with chloroquine chemoprophylaxis. In conclusion, we show that immune signatures of liver stage antigens, but neither an established rodent malaria model nor concentrations of antibodies against the major surface protein of sporozoites, permit prediction of vaccine efficacy. Thus, this study provides a clear rationale for the development of live sporozoite vaccination protocols that boost exposure to Pf liver stage antigens.Significance StatementOur research demonstrates that attenuation of liver infection of high doses of Plasmodium falciparum sporozoites by concomitant single-dose administration of atovaquone-proguanil is safe in humans. However, vaccine efficacy was modest when compared to an identical protocol using chloroquine that acts only on the subsequent blood infection. Immune signatures of secreted P. falciparum liver stage antigens, but neither an established rodent malaria model nor concentrations of sporozoite antibodies, permit prediction of vaccine efficacy.

scholarly journals Effectiveness of BNT162b2 and mRNA-1273 COVID-19 vaccines against symptomatic SARS-CoV-2 infection and severe COVID-19 outcomes in Ontario, Canada

2021 ◽  
Author(s):  
Hannah Chung ◽  
Siyi He ◽  
Sharifa Nasreen ◽  
Maria Sundaram ◽  
Sarah A Buchan ◽  
...  
Keyword(s):  
Older Adults ◽  
Logistic Regression ◽  
Single Dose ◽  
Outcome Measures ◽  
Vaccine Dose ◽  
Community Dwelling ◽  
Administrative Databases ◽  
Rt Pcr ◽  
Symptomatic Infection ◽  
Younger Adults

Objectives: To estimate the effectiveness of one and two doses of mRNA COVID-19 vaccines against symptomatic infection and severe outcomes. Design: Using a test-negative design study and linked laboratory, vaccination, and health administrative databases, we estimated adjusted vaccine effectiveness (aVE) against symptomatic infection and severe outcomes (hospitalization or death) using multivariable logistic regression. Setting: Ontario, Canada between 14 December 2020 and 19 April 2021. Participants: Community-dwelling adults aged ≥16 years who were tested for SARS-CoV-2 and had COVID-19 symptoms. Interventions: Pfizer-BioNTech's BNT162b2 or Moderna's mRNA-1273 vaccine. Main outcome measures: Laboratory-confirmed SARS-CoV-2 identified by RT-PCR; hospitalization or death associated with SARS-CoV-2 infection. Results: Among 324,033 symptomatic individuals, 53,270 (16.4%) were positive for SARS-CoV-2 and 21,272 (6.6%) received 1 or more vaccine dose. Among test-positive cases, 2,479 (4.7%) had a severe outcome. aVE against symptomatic infection 14 days or more after receiving only 1 dose was 60% (95%CI, 57 to 64%), increasing from 48% (95%CI, 41 to 54%) at 14-20 days after the first dose to 71% (95%CI, 63 to 78%) at 35-41 days. aVE 7 days or more after receiving 2 doses was 91% (95%CI, 89 to 93%). Against severe outcomes, aVE 14 days or more after receiving 1 dose was 70% (95%CI, 60 to 77%), increasing from 62% (95%CI, 44 to 75%) at 14-20 days to 91% (95%CI, 73 to 97%) at 35 days or more, whereas aVE 7 days or more after receiving 2 doses was 98% (95%CI, 88 to 100%). For adults aged 70 years and older, aVE estimates were lower after receiving 1 dose, but were comparable to younger adults after 28 days. After 2 doses, we observed high aVE against E484K-positive variants. Conclusions: Two doses of BNT162b2 and mRNA-1273 vaccines are highly effective against both symptomatic infection and severe outcomes. Effectiveness is lower after only a single dose, particularly for older adults shortly after the first dose.

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 Pertussis outbreak in Southern Ethiopia: challenges of detection, management and response

2020 ◽  
Author(s):  
Aychiluhim Damtew Mitiku ◽  
Mesele Damte Argaw ◽  
Binyam Fekadu Desta ◽  
Zergu Taffesse Tsegaye ◽  
Afework Ayele Atsa ◽  
...  
Keyword(s):  
Attack Rate ◽  
Health Workers ◽  
Vaccine Dose ◽  
Lessons Learned ◽  
Cold Chain ◽  
Southern Ethiopia ◽  
Cross Sectional ◽  
Middle Income ◽  
Middle Income Countries ◽  
Low And Middle Income

Abstract Background: Despite the availability of effective vaccines, pertussis remains endemic with high fatality rates in low and middle-income countries (LMIC).This study aims to describe an outbreak of pertussis in a health district of Ethiopia. The study highlights the challenges faced by the health system in identifying pertussis cases and appropriately responding to the outbreak at the district level. Methods: a descriptive cross-sectional study was conducted using data sourced from the District Public Health Emergency and Management (PHEM) surveillance service and outbreak management field reports. Stratified attack rates and fatality rates for pertussis are described. Systemic problems leading to the outbreak are explored and narrated. A modified CDC pertussis case definition was employed with a polymerase chain reaction used to confirm cases. Results: From September 2018 to January 2019, 1840 suspected, probable, and confirmed pertussis cases and six deaths were identified. Pertussis cases ranged from 1 month to 51 years in age and an outbreak occurred in 14 out of the 24 villages of Dara Malo district. The overall attack rate was 1708 per 100,000 population with a fatality rate of 3.3 per 1,000 pertussis cases. The highest attack rate of 12,689/100,000 was seen in infants. Among confirmed, probable and suspected pertussis cases, only 41.1% had completed the three-dose pertussis vaccine's primary schedule. The household survey revealed the population coverage of 73.4% and 40.8% for Pentavalent vaccine dose one and three respectively. Investigations suggested the existence of a poor cold chain management system in the study area. Conclusions: There is an urgent need to build capacity to strengthen routine vaccination services and improving the maintenance of the vaccine cold chain. Other Low-and Middle -Income Countries (LMICs), are urged to take lessons learned from this outbreak and strengthen their own vaccination programs and capacitate health workers to manage local outbreaks.

scholarly journals Robust spike antibody responses and increased reactogenicity in seropositive individuals after a single dose of SARS-CoV-2 mRNA vaccine

2021 ◽  
Author(s):  
Florian Krammer ◽  
Komal Srivastava ◽  
Viviana Simon ◽  
Keyword(s):  
Single Dose ◽  
Antibody Response ◽  
Vaccine Dose ◽  
Antibody Responses ◽  
Short Report ◽  
The Past ◽  
Antibody Titers

AbstractAn important question is arising as COVID-19 vaccines are getting rolled out: Should individuals who already had a SARS-CoV-2 infection receive one or two shots of the currently authorized mRNA vaccines. In this short report, we show that the antibody response to the first vaccine dose in individuals with pre-existing immunity is equal to or even exceeds the titers found in naïve individuals after the second dose. We also show that the reactogenicity is significantly higher in individuals who have been infected with SARS-CoV-2 in the past. Changing the policy to give these individuals only one dose of vaccine would not negatively impact on their antibody titers, spare them from unnecessary pain and free up many urgently needed vaccine doses.

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 Immunogenicity and reactogenicity of the adult tetanus–diphtheria vaccine. How many doses are necessary?

2001 ◽  
Vol 127 (3) ◽  
pp. 451-460 ◽  
Author(s):  
J. M. BAYAS ◽  
A. VILELLA ◽  
M. J. BERTRAN ◽  
J. VIDAL ◽  
J. BATALLA ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Single Dose ◽  
Vaccine Dose ◽  
Age Group ◽  
Adult Type ◽  
Group I ◽  
Dtp Vaccine ◽  
Group Ii ◽  
Young Subjects ◽  
Tetanus Antibodies

The immunogenicity and reactogenicity of the tetanus–diphtheria adult type vaccine was compared in two groups: group I (n = 201, 18–30 years old, presumably vaccinated with the DTP vaccine) and group II (n = 147, [ges ] 45 years old, without vaccination antecedents). Before vaccination, the seroprotection levels for tetanus were 90·5% (group I) and 30·6% (group II). These rose to 99·5% and 81·7%, respectively, after administration of one vaccine dose. For diphtheria, prevaccination seroprotection levels were 38·3% (group I) and 19·0% (group II). These rose to 85·8% and 65·7%, respectively, after vaccination. The logistic regression analysis showed an association between antibody titre and age. In group II, 3 doses of Td vaccine were needed to reach titres similar to those achieved in group I with a single dose. Stated reactogenicity was greater in: young subjects, women, those with higher titres of tetanus antibodies and those receiving other vaccines simultaneously. These results confirm the need for vaccination schedules adapted to the characteristics of each population age-group.

scholarly journals 2754. Phase 1 Trial of an mRNA-Based Combination Vaccine Against hMPV and PIV3

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S970-S970 ◽  
Author(s):  
Christine Shaw ◽  
Heather Lee ◽  
Conor Knightly ◽  
Shiva Kalidindi ◽  
Tal Zaks ◽  
...  
Keyword(s):  
Single Dose ◽  
Respiratory Tract ◽  
Neutralizing Antibodies ◽  
Phase 1 ◽  
Geometric Mean ◽  
Vaccine Dose ◽  
Neutralizing Antibody ◽  
Combination Vaccine ◽  
Tract Infections ◽  
Dose Levels

Abstract Background Human metapneumovirus (hMPV) and parainfluenza virus type 3 (PIV3) are important causes of upper and lower respiratory tract infections, particularly in young children. Despite their public health impact, no effective therapeutic or preventive options are available. mRNA-1653 is a mRNA-based investigational combination vaccine against hMPV and PIV3, and consists of two distinct mRNA sequences encoding the fusion proteins of hMPV and PIV3, co-formulated in lipid nanoparticles. Methods This phase 1, first-in-human, randomized, placebo-controlled, dose-ranging study assesses the safety and immunogenicity of mRNA-1653 in healthy adults aged 18–49. The 124-subject study evaluates four vaccine dose levels (25, 75, 150, and 300 µg) administered intramuscularly in either single-dose or two-dose (Day 1, Month 1) vaccination schedules, with follow-up through 1 year after the last vaccination. Objectives include safety and immunogenicity measured by hMPV- and PIV3-specific neutralizing antibody titers. Results An interim analysis demonstrated that the mRNA-1653 vaccine was generally well-tolerated at all dose levels. Neutralizing antibodies against hMPV and PIV3 were present at baseline in all subjects, consistent with prior exposure to both viruses. A single dose of mRNA-1653 boosted serum neutralization titers against both hMPV and PIV3, and the magnitude of boosting was similar at all dose levels. The geometric mean ratio of Month 1 to baseline titers was approximately 6 for hMPV and 3 for PIV3. A second dose of mRNA-1653 at Month 1 was not associated with further increase of hMPV or PIV3 neutralization titers. Conclusion mRNA-1653 is well-tolerated and induces a functional immune response, and is therefore a promising vaccine candidate for the prevention of pediatric respiratory tract diseases caused by hMPV and PIV3. Disclosures All authors: No reported disclosures.

scholarly journals Immune responses to a single dose of the AZD1222/Covishield vaccine in health care workers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chandima Jeewandara ◽  
Achala Kamaladasa ◽  
Pradeep Darshana Pushpakumara ◽  
Deshni Jayathilaka ◽  
Inoka Sepali Aberathna ◽  
...  
Keyword(s):  
Health Care ◽  
Single Dose ◽  
Health Care Workers ◽  
Ex Vivo ◽  
Vaccine Dose ◽  
Neutralization Assay ◽  
Wild Type Virus ◽  
Care Workers ◽  
And Gender ◽  
Blocking Antibodies

AbstractSeveral COVID-19 vaccines have received emergency approval. Here we assess the immunogenicity of a single dose of the AZD1222 vaccine, at one month, in a cohort of health care workers (HCWs) (629 naïve and 26 previously infected). 93.4% of naïve HCWs seroconverted, irrespective of age and gender. Haemagglutination test for antibodies to the receptor binding domain (RBD), surrogate neutralization assay (sVNT) and ex vivo IFNγ ELISpot assays were carried out in a sub-cohort. ACE2 blocking antibodies (measured by sVNT) were detected in 67/69 (97.1%) of naïve HCWs. Antibody levels to the RBD of the wild-type virus were higher than to RBD of B.1.1.7, and titres to B.1.351 were very low. Ex vivo T cell responses were observed in 30.8% to 61.7% in naïve HCWs. Previously infected HCWs, developed significantly higher (p < 0.0001) ACE2 blocking antibodies and antibodies to the RBD for the variants B.1.1.7 and B.1.351. This study shows high seroconversion after one vaccine dose, but also suggests that one vaccine dose may be insufficient to protect against emerging variants.

Sign in / Sign up

Export Citation Format

Share Document