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2.
Can J Public Health ; 2022 Apr 27.
Article in English | MEDLINE | ID: covidwho-1818845

ABSTRACT

OBJECTIVE: To investigate COVID-19 vaccine uptake and intent among pregnant people in Canada, and determine associated factors. METHODS: We conducted a national cross-sectional survey among pregnant people from May 28 through June 7, 2021 (n = 193). Respondents completed a questionnaire to determine COVID-19 vaccine acceptance (defined as either received or intend to receive a COVID-19 vaccine during pregnancy), factors associated with vaccine acceptance, and rationale for accepting/not accepting the vaccine. RESULTS: Of 193 respondents, 57.5% (n = 111) reported COVID-19 vaccine acceptance. Among those who did not accept the vaccine, concern over vaccine safety was the most commonly cited reason (90.1%, n = 73), and 81.7% (n = 67) disagreed with receiving a vaccine that had not been tested in pregnant people. Confidence in COVID-19 vaccine safety (aOR 16.72, 95% CI: 7.22, 42.39), Indigenous self-identification (aOR 11.59, 95% CI: 1.77, 117.18), and employment in an occupation at high risk for COVID-19 exposure excluding healthcare (aOR 4.76, 95% CI: 1.32, 18.60) were associated with vaccine acceptance. Perceived personal risk of COVID-19 disease was not associated with vaccine acceptance in the multivariate model. CONCLUSION: Vaccine safety is a primary concern for this population. Safety information should be communicated to this population as it emerges, along with clear messaging on the benefits of vaccination, as disease risk is either poorly understood or poorly valued in this population.


RéSUMé: OBJECTIF: Examiner l'intention de se faire vacciner contre la COVID-19 et l'adoption du vaccin anti-COVID-19 chez les personnes enceintes au Canada, et déterminer les facteurs associés. MéTHODE: Du 28 mai au 7 juin 2021, nous avons mené un sondage transversal national auprès de personnes enceintes (n = 193). Les répondantes ont rempli un questionnaire pour nous permettre de déterminer l'acceptation du vaccin contre la COVID-19 (définie comme le fait d'avoir reçu ou l'intention de recevoir un vaccin anti-COVID-19 durant la grossesse), les facteurs associés à l'acceptation du vaccin et les motifs d'acceptation ou de refus du vaccin. RéSULTATS: Sur les 193 répondantes, 57,5 % (n = 111) ont dit accepter le vaccin contre la COVID-19. Chez celles qui n'acceptaient pas le vaccin, l'inquiétude face à son innocuité était la raison la plus souvent citée (90,1 %, n = 73), et 81,7 % (n = 67) n'acceptaient pas de recevoir un vaccin qui n'avait pas été testé sur des personnes enceintes. La confiance en l'innocuité du vaccin anti-COVID-19 (RCa 16,72, IC de 95 % : 7,22, 42,39), l'auto-identification en tant que personne autochtone (RCa 11,59, IC de 95 % : 1,77, 117,18) et l'emploi dans une profession à risque élevé d'exposition à la COVID-19, sauf les soins de santé (RCa 4,76, IC de 95 % : 1,32, 18,60) étaient associés à l'acceptation du vaccin. Le risque personnel perçu de tomber malade de la COVID-19 n'était pas associé à l'acceptation du vaccin dans notre modèle multivarié. CONCLUSION: L'innocuité du vaccin est une préoccupation majeure dans cette population. Des informations sur l'innocuité devraient être communiquées aux personnes enceintes au fur et à mesure qu'elles sont connues, ainsi que des messages clairs sur les avantages de la vaccination, car le risque de maladie est soit mal compris, soit déconsidéré dans cette population.

3.
Vaccine ; 40(24): 3305-3312, 2022 May 26.
Article in English | MEDLINE | ID: covidwho-1805293

ABSTRACT

BACKGROUND: Background incidence rates are critical in pharmacovigilance to facilitate identification of vaccine safety signals. We estimated background incidence rates of 11 adverse events of special interest related to COVID-19 vaccines in Ontario, Canada. METHODS: We conducted a population-based retrospective observational study using linked health administrative databases for hospitalizations and emergency department visits among Ontario residents. We estimated incidence rates of Bell's palsy, idiopathic thrombocytopenia, febrile convulsions, acute disseminated encephalomyelitis, myocarditis, pericarditis, Kawasaki disease, Guillain-Barré syndrome, transverse myelitis, acute myocardial infarction, and anaphylaxis during five pre-pandemic years (2015-2019) and 2020. RESULTS: The average annual population was 14 million across all age groups with 51% female. The pre-pandemic mean annual rates per 100,000 population during 2015-2019 were 191 for acute myocardial infarction, 43.9 for idiopathic thrombocytopenia, 28.8 for anaphylaxis, 27.8 for Bell's palsy, 25.0 for febrile convulsions, 22.8 for acute disseminated encephalomyelitis, 11.3 for myocarditis/pericarditis, 8.7 for pericarditis, 2.9 for myocarditis, 2.0 for Kawasaki disease, 1.9 for Guillain-Barré syndrome, and 1.7 for transverse myelitis. Females had higher rates of acute disseminated encephalomyelitis, transverse myelitis and anaphylaxis while males had higher rates of myocarditis, pericarditis, and Guillain-Barré syndrome. Bell's palsy, acute disseminated encephalomyelitis, and Guillain-Barré syndrome increased with age. The mean rates of myocarditis and/or pericarditis increased with age up to 79 years; males had higher rates than females: from 12 to 59 years for myocarditis and ≥12 years for pericarditis. Febrile convulsions and Kawasaki disease were predominantly childhood diseases and generally decreased with age. CONCLUSIONS: Our estimated background rates will permit estimating numbers of expected events for these conditions and facilitate detection of potential safety signals following COVID-19 vaccination.


Subject(s)
COVID-19 Vaccines , COVID-19 , Anaphylaxis/chemically induced , Anaphylaxis/epidemiology , Bell Palsy/chemically induced , Bell Palsy/epidemiology , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Vaccines/adverse effects , Encephalomyelitis, Acute Disseminated/chemically induced , Encephalomyelitis, Acute Disseminated/epidemiology , Female , Guillain-Barre Syndrome/chemically induced , Guillain-Barre Syndrome/epidemiology , Humans , Incidence , Male , Mucocutaneous Lymph Node Syndrome/chemically induced , Mucocutaneous Lymph Node Syndrome/epidemiology , Myelitis, Transverse/chemically induced , Myelitis, Transverse/epidemiology , Myocardial Infarction/chemically induced , Myocardial Infarction/epidemiology , Myocarditis/chemically induced , Myocarditis/epidemiology , Ontario/epidemiology , Pericarditis/chemically induced , Pericarditis/epidemiology , Purpura, Thrombocytopenic, Idiopathic/chemically induced , Retrospective Studies , Seizures, Febrile/chemically induced , Seizures, Febrile/epidemiology
4.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-334181

ABSTRACT

Background As of December 30, 2021, Ontario long-term care (LTC) residents who received a third dose of COVID-19 vaccine ≥84 days previously were offered a fourth dose to prevent a surge in COVID-19-related morbidity and mortality due to the Omicron variant. Methods We used a test-negative design and linked databases to estimate the marginal effectiveness (4 versus 3 doses) and vaccine effectiveness (VE;2, 3, or 4 doses versus no doses) of mRNA vaccines among Ontario LTC residents aged ≥60 years who were tested for SARS-CoV-2 between December 30, 2021 and March 2, 2022. Outcome measures included any Omicron infection, symptomatic infection, and severe outcomes (hospitalization or death). Results We included 9,957 Omicron cases and 46,849 test-negative controls. The marginal effectiveness of a fourth dose ≥7 days after vaccination versus a third dose received ≥84 days prior was 40% (95% Confidence Interval[CI], 34-45%) against infection, 63% (95%CI, 51-71%) against symptomatic infection, and 54% (95%CI, 31-70%) against severe outcomes. VE (compared to an unvaccinated group) increased with each additional dose, and for a fourth dose was 65% (95%CI, 60-70%), 87% (95%CI, 81-91%), and 92% (95%CI, 87-95%), against infection, symptomatic infection, and severe outcomes, respectively. Conclusions Our findings suggest that compared to a third dose received ≥84 days ago, a fourth dose recommendation for LTC residents improved protection against infection, symptomatic infection, and severe outcomes caused by Omicron. Compared to unvaccinated individuals, fourth doses provide strong protection against symptomatic infection and severe outcomes but the duration of protection remains unknown.

5.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-332806

ABSTRACT

Introduction Data on vaccine effectiveness (VE) against Omicron in adolescents are limited. We estimated 2-dose and 3-dose VE against Omicron and Delta in adolescents aged 12-17 years in Ontario, Canada. Methods We conducted a test-negative design study among SARS-CoV-2-tested adolescents aged 12-17 years between November 22, 2021 (date of first Omicron detection) and March 6, 2022;we assessed Delta outcomes prior to January 2, 2022. We used multivariable logistic regression to compare the odds of vaccination in cases to symptomatic test-negative controls and calculated VE as 1-adjusted odds ratio. Results VE was lower against symptomatic Omicron infection than against Delta and decreased more rapidly over time, from 51% (95%CI, 38-61%) in the 7-59 days following a second dose to 29% (95%CI, 17-38%) after 180 days, compared to 97% (95%CI, 94-99%) and 90% (95%CI, 79-95%) for the same intervals against symptomatic Delta infection. Overall, 2-dose VE against severe outcomes caused by Omicron was 85% (95%CI, 74-91%) ≥7 days following a second dose and estimates were similar over time. VE against symptomatic Omicron infection was 62% (95%CI, 49-72%) ≥7 days following a third dose. Discussion Two-dose VE against symptomatic Omicron infection wanes over time in adolescents. While lower than observed against Delta, protection against severe outcomes appears to be maintained over time. A third dose substantially improves protection against Omicron infection, but 3-dose VE is only moderate at approximately 60% in the early period following vaccination and the duration of this protection is unknown.

6.
JAMA ; 327(15): 1478-1487, 2022 04 19.
Article in English | MEDLINE | ID: covidwho-1756509

ABSTRACT

Importance: There is limited comparative epidemiological evidence on outcomes associated with COVID-19 vaccination during pregnancy; monitoring pregnancy outcomes in large populations is required. Objective: To evaluate peripartum outcomes following COVID-19 vaccination during pregnancy. Design, Setting, and Participants: Population-based retrospective cohort study in Ontario, Canada, using a birth registry linked with the provincial COVID-19 immunization database. All births between December 14, 2020, and September 30, 2021, were included. Exposures: COVID-19 vaccination during pregnancy, COVID-19 vaccination after pregnancy, and no vaccination. Main Outcomes and Measures: Postpartum hemorrhage, chorioamnionitis, cesarean delivery (overall and emergency cesarean delivery), admission to neonatal intensive care unit (NICU), and low newborn 5-minute Apgar score (<7). Linear and robust Poisson regression was used to generate adjusted risk differences (aRDs) and risk ratios (aRRs), respectively, comparing cumulative incidence of outcomes in those who received COVID-19 vaccination during pregnancy with those vaccinated after pregnancy and those with no record of COVID-19 vaccination at any point. Inverse probability of treatment weights were used to adjust for confounding. Results: Among 97 590 individuals (mean [SD] age, 31.9 [4.9] years), 22 660 (23%) received at least 1 dose of COVID-19 vaccine during pregnancy (63.6% received dose 1 in the third trimester; 99.8% received an mRNA vaccine). Comparing those vaccinated during vs after pregnancy (n = 44 815), there were no significantly increased risks of postpartum hemorrhage (incidence: 3.0% vs 3.0%; aRD, -0.28 per 100 individuals [95% CI, -0.59 to 0.03]; aRR, 0.91 [95% CI, 0.82-1.02]), chorioamnionitis (0.5% vs 0.5%; aRD, -0.04 per 100 individuals [95% CI, -0.17 to 0.09]; aRR, 0.92 [95% CI, 0.70-1.21]), cesarean delivery (30.8% vs 32.2%; aRD, -2.73 per 100 individuals [95% CI, -3.59 to -1.88]; aRR, 0.92 [95% CI, 0.89-0.95]), NICU admission (11.0% vs 13.3%; aRD, -1.89 per 100 newborns [95% CI, -2.49 to -1.30]; aRR, 0.85 [95% CI, 0.80-0.90]), or low Apgar score (1.8% vs 2.0%; aRD, -0.31 per 100 newborns [95% CI, -0.56 to -0.06]; aRR, 0.84 [95% CI, 0.73-0.97]). Findings were qualitatively similar when compared with individuals who did not receive COVID-19 vaccination at any point (n = 30 115). Conclusions and Relevance: In this population-based cohort study in Ontario, Canada, COVID-19 vaccination during pregnancy, compared with vaccination after pregnancy and with no vaccination, was not significantly associated with increased risk of adverse peripartum outcomes. Study interpretation should consider that the vaccinations received during pregnancy were primarily mRNA vaccines administered in the second and third trimester.


Subject(s)
COVID-19 Vaccines , COVID-19 , Chorioamnionitis , Infant, Newborn, Diseases , Postpartum Hemorrhage , Adult , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Vaccines/adverse effects , Chorioamnionitis/epidemiology , Chorioamnionitis/etiology , Cohort Studies , Female , Humans , Infant, Newborn , Infant, Newborn, Diseases/epidemiology , Ontario/epidemiology , Peripartum Period , Postpartum Hemorrhage/epidemiology , Postpartum Hemorrhage/etiology , Pregnancy , Pregnancy Outcome/epidemiology , Retrospective Studies , Vaccination/adverse effects , Vaccines, Synthetic
7.
PLoS One ; 17(3): e0264232, 2022.
Article in English | MEDLINE | ID: covidwho-1753189

ABSTRACT

BACKGROUND: Health care workers (HCWs) are particularly exposed to COVID-19 and therefore it is important to study preventive measures in this population. AIM: To investigate socio-demographic factors and professional practice associated with the risk of COVID-19 among HCWs in health establishments in Normandy, France. METHODS: A cross-sectional and 3 case-control studies using bootstrap methods were conducted in order to explore the possible risk factors that lead to SARS-CoV2 transmission within HCWs. Case-control studies focused on risk factors associated with (a) care of COVID-19 patients, (b) care of non COVID-19 patients and (c) contacts between colleagues. PARTICIPANTS: 2,058 respondents, respectively 1,363 (66.2%) and 695 (33.8%) in medical and medico-social establishments, including HCW with and without contact with patients. RESULTS: 301 participants (14.6%) reported having been infected by SARS-CoV2. When caring for COVID-19 patients, HCWs who declared wearing respirators, either for all patient care (ORa 0.39; 95% CI: 0.29-0.51) or only when exposed to aerosol-generating procedures (ORa 0.56; 95% CI: 0.43-0.70), had a lower risk of infection compared with HCWs who declared wearing mainly surgical masks. During care of non COVID-19 patients, wearing mainly a respirator was associated with a higher risk of infection (ORa 1.84; 95% CI: 1.06-3.37). An increased risk was also found for HCWs who changed uniform in workplace changing rooms (ORa 1.93; 95% CI: 1.63-2.29). CONCLUSION: Correct use of PPE adapted to the situation and risk level is essential in protecting HCWs against infection.


Subject(s)
COVID-19/prevention & control , Communicable Disease Control/instrumentation , Disease Transmission, Infectious/prevention & control , Health Personnel/classification , Occupational Exposure/prevention & control , Adult , COVID-19/epidemiology , Case-Control Studies , Cross-Sectional Studies , Disease Transmission, Infectious/statistics & numerical data , Female , France , Humans , Male , Middle Aged , Occupational Exposure/statistics & numerical data , Personal Protective Equipment , Professional Practice , Risk Reduction Behavior
8.
Emergency Medicine Journal : EMJ ; 39(3):252, 2022.
Article in English | ProQuest Central | ID: covidwho-1708940

ABSTRACT

Aims/Objectives/BackgroundThe non-specific symptoms of COVID-19 and the lack of a highly-sensitive point-of-care test make it difficult to reliably detect and diagnose in acute care settings. The early identification of COVID-19 using chest X-rays (CXR) in the Emergency Department (ED) is a crucial skill for frontline clinicians. We wanted to measure the accuracy of ED clinicians in detecting COVID-19 CXR changes and assess for improvement using an adaptive online learning module.Methods/DesignED clinicians working across five hospitals in the Thames Valley Emergency medicine Research Network (TaVERN) were recruited over six months. Participants’ reporting performance was assessed by interpreting 30 anonymised CXR via the Report and Image Quality Control (RAIQC) online platform, using an image bank which contained both COVID-19 and non-COVID-19 pathological findings. Participants subsequently completed an online training module, and repeated the assessment using different image sets. Diagnostic accuracy and speed of CXR reporting was assessed both before and after training, with results compared against radiologists. The ground truth for each case was established by consensus of three thoracic radiologists. RT-PCR results were reviewed for each case to ensure that all the COVID-19 cases were positive and all COVID-19 cases were negative.Results/ConclusionsED clinicians working in emergency departments across five hospitals in the Thames Valley Emergency Medicine Research Network (TaVERN) were recruited over a six month period. 112 clinicians completed the initial assessment. 56 clinicians completed all three training components. The initial mean accuracy for clinicians in identifying COVID-19 on chest X-rays was 43%. The mean accuracy was 57% amongst clinicians who completed all three online training components. These clinician showed improved reporting speed with mean time reduction to CXR interpretation from 69 to 50 seconds.ED clinicians do not perform well at detecting COVID-19 CXR related changes on CXR, but accuracy and speed can be improved by online training.

9.
BMJ Paediatrics Open ; 6(1), 2022.
Article in English | ProQuest Central | ID: covidwho-1685643

ABSTRACT

Paediatric emergency department (PED) attendances reduced worldwide during the COVID-19 pandemic (2020) but anecdotally babies under 30 days (BUD) appeared less affected. We collated monthly PED attendances (16 years and under) across four hospitals (three district general hospitals and a tertiary specialist PED) in England, UK from January 2017 to December 2020. Gross PED attendances dropped by 34% in 2020 (n=98 256) compared to 2019 (n=148 640). However, cumulative BUD attendances dropped by only 6% in 2020 (n=3922) compared to 2019 (n=4162). Monthly site-specific attendances showed marginal variation. PED attendances broadly decreased in 2020 with less of an impact on BUD.

10.
Nat Microbiol ; 7(3): 379-385, 2022 03.
Article in English | MEDLINE | ID: covidwho-1671571

ABSTRACT

SARS-CoV-2 variants of concern (VOC) are more transmissible and may have the potential for increased disease severity and decreased vaccine effectiveness. We estimated the effectiveness of BNT162b2 (Pfizer-BioNTech Comirnaty), mRNA-1273 (Moderna Spikevax) and ChAdOx1 (AstraZeneca Vaxzevria) vaccines against symptomatic SARS-CoV-2 infection and COVID-19 hospitalization or death caused by the Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1) and Delta (B.1.617.2) VOC in Ontario, Canada, using a test-negative design study. We identified 682,071 symptomatic community-dwelling individuals who were tested for SARS-CoV-2, and 15,269 individuals with a COVID-19 hospitalization or death. Effectiveness against symptomatic infection ≥7 d after two doses was 89-92% against Alpha, 87% against Beta, 88% against Gamma, 82-89% against Beta/Gamma and 87-95% against Delta across vaccine products. The corresponding estimates ≥14 d after one dose were lower. Effectiveness estimates against hospitalization or death were similar to or higher than against symptomatic infection. Effectiveness against symptomatic infection was generally lower for older adults (≥60 years) than for younger adults (<60 years) for most of the VOC-vaccine combinations. Our findings suggest that jurisdictions facing vaccine supply constraints may benefit from delaying the second dose in younger individuals to more rapidly achieve greater overall population protection; however, older adults would likely benefit most from minimizing the delay in receiving the second dose to achieve adequate protection against VOC.


Subject(s)
/immunology , COVID-19/prevention & control , SARS-CoV-2/immunology , /administration & dosage , Adolescent , Adult , Aged , Aged, 80 and over , /genetics , COVID-19/epidemiology , COVID-19/mortality , COVID-19/virology , /genetics , Female , Humans , Male , Middle Aged , Ontario/epidemiology , SARS-CoV-2/classification , SARS-CoV-2/genetics , Young Adult
11.
Diagn Microbiol Infect Dis ; 102(4): 115631, 2022 Apr.
Article in English | MEDLINE | ID: covidwho-1670407

ABSTRACT

One SARS-CoV-2-positive sample demonstrated impaired detection of the N1 target by RT-PCR using US CDC primer/probe sets. A 3 nucleotide deletion was discovered that overlaps the forward primer binding site. This finding underscores the importance of continued SARS-CoV-2 mutation surveillance and assessment of the impact on diagnostic test performance.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , DNA Primers/genetics , Humans , RNA, Viral/analysis , RNA, Viral/genetics , SARS-CoV-2/genetics , Sensitivity and Specificity
12.
Diagnostic microbiology and infectious disease ; 2021.
Article in English | EuropePMC | ID: covidwho-1602617

ABSTRACT

One SARS-CoV-2-positive sample demonstrated impaired detection of the N1 target by RT-PCR using US CDC primer/probe sets. A three nucleotide deletion was discovered that overlaps the forward primer binding site. This finding underscores the importance of continued SARS-CoV-2 mutation surveillance and assessment of the impact on diagnostic test performance.

13.
BMJ Open ; 11(12): e052019, 2021 12 17.
Article in English | MEDLINE | ID: covidwho-1583101

ABSTRACT

OBJECTIVE: The objective of this study was to estimate background rates of selected thromboembolic and coagulation disorders in Ontario, Canada. DESIGN: Population-based retrospective observational study using linked health administrative databases. Records of hospitalisations and emergency department visits were searched to identify cases using International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Canada diagnostic codes. PARTICIPANTS: All Ontario residents. PRIMARY OUTCOME MEASURES: Incidence rates of ischaemic stroke, intracerebral haemorrhage, subarachnoid haemorrhage, deep vein thrombosis, pulmonary embolism, idiopathic thrombocytopaenia, disseminated intravascular coagulation and cerebral venous thrombosis during five prepandemic years (2015-2019) and 2020. RESULTS: The average annual population was 14 million with 51% female. The mean annual rates per 100 000 population during 2015-2019 were 127.1 (95% CI 126.2 to 127.9) for ischaemic stroke, 22.0 (95% CI 21.6 to 22.3) for intracerebral haemorrhage, 9.4 (95% CI 9.2 to 9.7) for subarachnoid haemorrhage, 86.8 (95% CI 86.1 to 87.5) for deep vein thrombosis, 63.7 (95% CI 63.1 to 64.3) for pulmonary embolism, 6.1 (95% CI 5.9 to 6.3) for idiopathic thrombocytopaenia, 1.6 (95% CI 1.5 to 1.7) for disseminated intravascular coagulation, and 1.5 (95% CI 1.4 to 1.6) for cerebral venous thrombosis. Rates were lower in 2020 than during the prepandemic years for ischaemic stroke, deep vein thrombosis and idiopathic thrombocytopaenia. Rates were generally consistent over time, except for pulmonary embolism, which increased from 57.1 to 68.5 per 100 000 between 2015 and 2019. Rates were higher for females than males for subarachnoid haemorrhage, pulmonary embolism and cerebral venous thrombosis, and vice versa for ischaemic stroke and intracerebral haemorrhage. Rates increased with age for most of these conditions, but idiopathic thrombocytopaenia demonstrated a bimodal distribution with incidence peaks at 0-19 years and ≥60 years. CONCLUSIONS: Our estimated background rates help contextualise observed events of these potential adverse events of special interest and to detect potential safety signals related to COVID-19 vaccines.


Subject(s)
Brain Ischemia , COVID-19 , Disseminated Intravascular Coagulation , Pulmonary Embolism , Stroke , Adolescent , Adult , COVID-19 Vaccines , Child , Child, Preschool , Emergency Service, Hospital , Female , Hospitalization , Humans , Incidence , Infant , Infant, Newborn , Male , Ontario/epidemiology , Pulmonary Embolism/epidemiology , SARS-CoV-2 , Stroke/epidemiology , Young Adult
14.
2021.
Preprint in English | Other preprints | ID: ppcovidwho-295584

ABSTRACT

ABSTRACT SARS-CoV-2 variants of concern (VOC) are more transmissible and have the potential for increased disease severity and decreased vaccine effectiveness. We estimated the effectiveness of BNT162b2 (Pfizer-BioNTech Comirnaty), mRNA-1273 (Moderna Spikevax), and ChAdOx1 (AstraZeneca Vaxzevria) vaccines against symptomatic SARS-CoV-2 infection and COVID-19 hospitalization or death caused by the Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), and Delta (B.1.617.2) VOCs in Ontario, Canada using a test-negative design study. Effectiveness against symptomatic infection ≥7 days after two doses was 89–92% against Alpha, 87% against Beta, 88% against Gamma, 82–89% against Beta/Gamma, and 87–95% against Delta across vaccine products. The corresponding estimates ≥14 days after one dose were lower. Effectiveness estimates against hospitalization or death were similar to, or higher than, against symptomatic infection. Effectiveness against symptomatic infection is generally lower for older adults (≥60 years) compared to younger adults (<60 years) for most of the VOC-vaccine combinations.

15.
2021.
Preprint in English | Other preprints | ID: ppcovidwho-294487

ABSTRACT

ABSTRACT Objectives To estimate the effectiveness of mRNA COVID-19 vaccines against symptomatic infection and severe outcomes. Design We applied a test-negative design study to linked laboratory, vaccination, and health administrative databases, and used multivariable logistic regression adjusting for demographic and clinical characteristics associated with SARS-CoV-2 and vaccine receipt to estimate vaccine effectiveness (VE) against symptomatic infection and severe outcomes. Setting Ontario, Canada between 14 December 2020 and 19 April 2021. Participants Community-dwelling adults aged ≥16 years who had COVID-19 symptoms and were tested for SARS-CoV-2. Interventions Pfizer-BioNTech’s BNT162b2 or Moderna’s mRNA-1273 vaccine. Main outcome measures Laboratory-confirmed SARS-CoV-2 by RT-PCR;hospitalization/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 vaccine dose. Among test-positive cases, 2,479 (4.7%) had a severe outcome. VE against symptomatic infection ≥14 days 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. VE ≥7 days after 2 doses was 91% (95%CI, 89 to 93%). Against severe outcomes, VE ≥14 days after 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, whereas VE ≥7 days after 2 doses was 98% (95%CI, 88 to 100%). For adults aged ≥70 years, VE estimates were lower for intervals shortly after receiving 1 dose, but were comparable to younger adults for all intervals after 28 days. After 2 doses, we observed high VE against E484K-positive variants. Conclusions Two doses of mRNA COVID-19 vaccines are highly effective against symptomatic infection and severe outcomes. Single-dose effectiveness is lower, particularly for older adults shortly after the first dose.

16.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-294330

ABSTRACT

Structured Abstract Importance: Increased rates of myocarditis/pericarditis following COVID-19 mRNA vaccines have been observed. However, little data are available related to product-specific differences, which have important programmatic impacts. Objective: The objective of this study was to estimate reporting rates of myocarditis/pericarditis following COVID-19 mRNA vaccine by product, age, sex, and dose number, as well inter-dose interval. Design: We conducted a population-based cohort study using passive vaccine safety surveillance data. All individuals in Ontario, Canada who received at least one dose of COVID-19 mRNA vaccine between December 14, 2020 and September 4, 2021 were included. Setting: This study was conducted in Ontario, Canada (population: 14.7 million) using the provincial COVID-19 vaccine registry and provincial adverse events following immunization database. Participants: We included all individuals with a reported episode of myocarditis/pericarditis following COVID-19 vaccine in the study period. We obtained information on all doses administered in the province to calculate reporting rates. Exposure: Receipt of COVID-19 mRNA vaccine (mRNA-1273 [Moderna Spikevax] or BNT162b2 [Pfizer-BioNTech Comirnaty]). Main Outcome(s) and Measure(s): Reported rate of myocarditis/pericarditis meeting level 1-3 of the Brighton Collaboration case definitions. Results: There were 19,740,741 doses of mRNA vaccines administered and 297 reports of myocarditis/pericarditis meeting our inclusion criteria. Among these, 69.7% occurred following the second dose of COVID-19 mRNA vaccine and 76.8% occurred in males. The median age of individuals with a reported event was 24 years. The highest reporting rate of myocarditis/pericarditis was observed in males aged 18-24 years following mRNA-1273 as the second dose;the rate in this age group was 5.1 (95% CI 1.9-15.5) times higher than the rate following BNT162b2 as the second dose. Overall reporting rates were higher when the inter-dose interval was shorter (i.e., ≤30 days) for both vaccine products. Among individuals who received mRNA-1273 for the second dose, rates were higher for those who had a heterologous as opposed to homologous vaccine schedule. Conclusions and Relevance: Our results suggest that vaccine product, inter-dose interval and vaccine schedule combinations may play a role in the risk of myocarditis/pericarditis, in addition to age and sex. Certain programmatic strategies could reduce the risk of myocarditis/pericarditis following mRNA vaccines.

17.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-293525

ABSTRACT

Structured Abstract Importance: Increased rates of myocarditis/pericarditis following COVID-19 mRNA vaccines have been observed. However, little data are available related to product-specific differences, which have important programmatic impacts. Objective: The objective of this study was to estimate reporting rates of myocarditis/pericarditis following COVID-19 mRNA vaccine by product, age, sex, and dose number, as well inter-dose interval. Design: We conducted a population-based cohort study using passive vaccine safety surveillance data. All individuals in Ontario, Canada who received at least one dose of COVID-19 mRNA vaccine between December 14, 2020 and September 4, 2021 were included. Setting: This study was conducted in Ontario, Canada (population: 14.7 million) using the provincial COVID-19 vaccine registry and provincial adverse events following immunization database. Participants: We included all individuals with a reported episode of myocarditis/pericarditis following COVID-19 vaccine in the study period. We obtained information on all doses administered in the province to calculate reporting rates. Exposure: Receipt of COVID-19 mRNA vaccine (mRNA-1273 [Moderna Spikevax] or BNT162b2 [Pfizer-BioNTech Comirnaty]). Main Outcome(s) and Measure(s): Reported rate of myocarditis/pericarditis meeting level 1-3 of the Brighton Collaboration case definitions. Results: There were 19,740,741 doses of mRNA vaccines administered and 297 reports of myocarditis/pericarditis meeting our inclusion criteria. Among these, 69.7% occurred following the second dose of COVID-19 mRNA vaccine and 76.8% occurred in males. The median age of individuals with a reported event was 24 years. The highest reporting rate of myocarditis/pericarditis was observed in males aged 18-24 years following mRNA-1273 as the second dose;the rate in this age group was 5.1 (95% CI 1.9-15.5) times higher than the rate following BNT162b2 as the second dose. Overall reporting rates were higher when the inter-dose interval was shorter (i.e., ≤30 days) for both vaccine products. Among individuals who received mRNA-1273 for the second dose, rates were higher for those who had a heterologous as opposed to homologous vaccine schedule. Conclusions and Relevance: Our results suggest that vaccine product, inter-dose interval and vaccine schedule combinations may play a role in the risk of myocarditis/pericarditis, in addition to age and sex. Certain programmatic strategies could reduce the risk of myocarditis/pericarditis following mRNA vaccines.

18.
Clin Infect Dis ; 73(10): 1840-1848, 2021 11 16.
Article in English | MEDLINE | ID: covidwho-1522143

ABSTRACT

BACKGROUND: Within-household transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been identified as one of the main sources of spread of coronavirus disease 2019 (COVID-19) after lockdown restrictions and self-isolation guidelines are implemented. Secondary attack rates among household contacts are estimated to be 5-10 times higher than among non-household contacts, but it is unclear which individuals are more prone to transmit infection within their households. METHODS: Using address matching, a cohort was assembled of all individuals with laboratory-confirmed COVID-19 residing in private households in Ontario, Canada. Descriptive analyses were performed to compare characteristics of cases in households that experienced secondary transmission versus those that did not. Logistic regression models were fit to determine index case characteristics and neighborhood characteristics associated with transmission. RESULTS: Between January and July 2020, there were 26 714 individuals with COVID-19 residing in 21 226 households. Longer testing delays (≥5 vs 0 days; odds ratio [OR], 3.02; 95% confidence interval [CI], 2.53-3.60) and male gender (OR, 1.28; 95% CI, 1.18-1.38) were associated with greater odds of household secondary transmission, while being a healthcare worker (OR, .56; 95% CI, .50-.62) was associated with lower odds of transmission. Neighborhoods with larger average family size and a higher proportion of households with multiple persons per room were also associated with greater odds of transmission. CONCLUSIONS: It is important for individuals to get tested for SARS-CoV-2 infection as soon as symptoms appear, and to isolate away from household contacts; this is particularly important in neighborhoods with large family sizes and/or crowded households.


Subject(s)
COVID-19 , SARS-CoV-2 , Cohort Studies , Communicable Disease Control , Family Characteristics , Humans , Male , Ontario/epidemiology
19.
Vaccine ; 39(52): 7669-7676, 2021 12 20.
Article in English | MEDLINE | ID: covidwho-1458645

ABSTRACT

BACKGROUND: Vaccinating children (≤17 years old) is important for controlling the COVID-19 pandemic. As parents are primary decision makers for their children, we aimed to assess parents' perceptions and intentions regarding COVID-19 vaccination for their children, including for some underserved populations (e.g., newcomers, Indigenous peoples, and visible minority groups). METHODS: We conducted a cross-sectional national survey of Canadian parents in December 2020, just as COVID-19 vaccines were approved for adults, to assess intention to vaccinate their children (aged 0-17 years) against COVID-19, perceptions of COVID-19 disease and vaccines, previous uptake of influenza and routine vaccines, and sociodemographic characteristics. Binomial logistic regression was used to assess the association between parents' lack of COVID-19 vaccination intention for their children and various independent variables. RESULTS: Sixty-three percent of parents (1074/1702) intended to vaccinate their children against COVID-19. Those employed part-time (compared to full-time) had lower intention to vaccinate their children (aOR = 1.73, 95% CI: 1.06-2.84), while those who spoke languages other than English, French, or Indigenous languages were less likely to have low intention (aOR = 0.55, 95% CI: 0.32-0.92). Low vaccination intention was also associated with children not receiving influenza vaccine pre-pandemic (aOR = 1.51, 95% CI: 1.04-2.21), parents having low intention to vaccinate themselves against COVID-19 (aOR = 9.22, 95% CI: 6.43-13.34), believing COVID-19 vaccination is unnecessary (aOR = 2.59, 95% CI: 1.72-3.91) or unsafe (aOR = 4.21, 95% CI: 2.96-5.99), and opposing COVID-19 vaccine use in children without prior testing (aOR = 3.09, 95% CI: 1.87-5.24). INTERPRETATION: Parents' COVID-19 vaccination intentions for their children are better predicted by previous decisions regarding influenza vaccination than routine childhood vaccines, and other perceptions of COVID-19 vaccine-related factors. Public communication should highlight the safety and necessity of COVID-19 vaccination in children to support a return to normal activities. Further research should assess actual COVID-19 vaccination uptake in children, particularly for underserved populations.


Subject(s)
COVID-19 Vaccines , COVID-19 , Adolescent , Canada , Child , Cross-Sectional Studies , Humans , Intention , Pandemics , Parents , SARS-CoV-2 , Vaccination
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