Accuracy of Self-Reported COVID-19 Vaccination Status Compared With a Public Health Vaccination Registry in Québec: Observational Diagnostic Study

Parent and family characteristics associated with reported pediatric influenza vaccination in a sample of Canadian digital vaccination platform users. An exploratory, cross-sectional study in the 2018-2019 influenza season

Seasonal vaccination remains one of the best interventions to prevent morbidity and mortality from influenza in children. Understanding the characteristics of parents who vaccinate their children can inform communication strategies to encourage immunization. Using a cross-sectional study, we described parental characteristics of people who reported vaccinating their children against influenza during 2018/2019 in a cohort of Canadian digital immunization record users. Data was collected from a free, Pan-Canadian digital vaccination tool, CANImmunize. Eligible accounts contained at least one parental and one "child/dependent" record. Each parental characteristic (gender, age, family size, etc) was tested for association with pediatric influenza vaccination, and a multivariate logistic regression model was fit. A total of 6,801 CANImmunize accounts met inclusion criteria. After collapsing the dataset, the final sample contained 11,381 unique dyads. Influenza vaccination was reported for 32.3% of the children and 42.0% of the parents. In the multivariate logistic regression analysis, parents receiving the seasonal influenza vaccine were most strongly associated with reporting pediatric influenza vaccination (OR 17.05, 95% CI 15.08, 19.28). Having a larger family size and fewer transactions during the study period was associated with not reporting pediatric influenza vaccination. While there are several limitations to this large-scale study, these results can help inform future research in the area. Digital technologies may provide a unique and valuable source of vaccine coverage data and to explore associations between individual characteristics and immunization behavior. Policy makers considering digital messaging may want to tailor their efforts based on parental characteristics to further improve pediatric seasonal influenza vaccine uptake.

Leveraging a clinical emergency department dataset to estimate two-dose COVID-19 vaccine effectiveness and duration of protection in Canada

BACKGROUND

During the COVID-19 pandemic, clinical care shifted toward virtual and Emergency Department care. We explored the feasibility of mRNA vaccine effectiveness (VE) estimation against SARS-CoV-2-related Emergency Department visits and hospitalizations using prospectively collected Emergency Department data.

METHODS

We estimated two-dose VE using a test-negative design and data from 10 participating sites of the Canadian COVID-19 Emergency Department Rapid Response Network (CCEDRRN). We included Emergency Department patients presenting with COVID-19 symptoms and nucleic acid amplification testing for SARS-CoV-2 between July 19 and December 31, 2021. We excluded patients with unclear vaccination and one or more than 2 vaccine doses by their Emergency Department visit.

RESULTS

Among 3,405 eligible patients, adjusted two-dose mRNA VE against SARS-CoV-2-related Emergency Department visits was 93.3 % (95 % CI 87.9-96.3 %) between 7-55 days, sustained over 80 % through 139 days post-vaccination. In stratified analyses, VE was similar among patients with select immune-compromising conditions, chronic kidney disease, lung disease, unstable housing, and reported illicit substance use.

CONCLUSIONS

Two-dose mRNA VE against SARS-CoV-2-related Emergency Department visit was high and sustained, including among vulnerable subgroups. Compared to administrative datasets, active Emergency Department enrolment enables standardization for testing access and indication and supports separate VE assessment among special population subgroups. Compared to other active enrolment settings, Emergency Departments more consistently function during crises when alternate healthcare sectors become variably closed.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT0470294.

Cervical Cancer Screening and Prevention Uptake in Females with Autism Spectrum Disorder

This study reports on uptake rates of cervical cancer prevention and screening in a clinically-referred cohort of adolescent and adult females with autism spectrum disorder (ASD). Females with ASD (11-65 years) were invited to participate in an online survey to report on uptake of the human papillomavirus (HPV) vaccination and cervical cancer screening. Participants also provided demographic and clinical information. Chi-square statistical analysis was utilized to examine the relationship between categorical variables and receipt of cervical cancer prevention and screening. Forty-one out of 73 (56%) of adolescent (11-17 years) and 51/108 (47%) of adult (≥ 18 years) females with ASD reported having received at least one dose of the HPV vaccine. Only 30/73 (41%) and 37/108 (34%) of adolescents and adults respectively, were fully vaccinated (≥ 2 doses). Language impairment was the only clinical factor found to be associated with non-receipt of the HPV vaccine. Thirty-one out of 82 (38%) adult females (≥ 21 years) with ASD had received at least one pap smear. Language impairment, intellectual disability, non-independent living, and lower level of education were all associated with not receiving a pap smear. Females with ASD are vulnerable to invasive cervical cancer disease due to low uptake rates of the HPV vaccine and routine pap smear screening.

Perceived Risk for Severe COVID-19 and Oral Antiviral Use Among Antiviral-Eligible US Adults

INTRODUCTION

Oral antiviral medications are important tools for preventing severe COVID-19 outcomes. However, their uptake remains low for reasons that are not entirely understood. Our study aimed to assess the association between perceived risk for severe COVID-19 outcomes and oral antiviral use among those who were eligible for treatment based on Centers for Disease Control and Prevention (CDC) guidelines.

METHODS

We surveyed 4034 non-institutionalized US adults in April 2023, and report findings from 934 antiviral-eligible participants with at least one confirmed SARS-CoV-2 infection since December 1, 2021 and no current long COVID symptoms. Survey weights were used to yield nationally representative estimates. The primary exposure of interest was whether participants perceived themselves to be "at high risk for severe COVID-19." The primary outcome was use of a COVID-19 oral antiviral within 5 days of suspected SARS-CoV-2 infection.

RESULTS

Only 18.5% of antiviral-eligible adults considered themselves to be at high risk for severe COVID-19 and 16.8% and 15.9% took oral antivirals at any time or within 5 days of SARS-CoV-2 infection, respectively. In contrast, 79.8% were aware of antiviral treatments for COVID-19. Perceived high-risk status was associated with being more likely to be aware (adjusted prevalence ratio [aPR]: 1.11 [95% confidence interval (CI) 1.03-1.20]), to be prescribed (aPR 1.47 [95% CI 1.08-2.01]), and to take oral antivirals at any time (aPR 1.61 [95% CI 1.16-2.24]) or within 5 days of infection (aPR 1.72 [95% CI 1.23-2.40]).

CONCLUSIONS

Despite widespread awareness of the availability of COVID-19 oral antivirals, more than 80% of eligible US adults did not receive them. Our findings suggest that differences between perceived and actual risk for severe COVID-19 (based on current CDC guidelines) may partially explain this low uptake.

Characteristics and outcomes of patients with COVID-19 who return to the emergency department: a multicentre observational study by the Canadian COVID-19 Emergency Department Rapid Response Network (CCEDRRN)

OBJECTIVE

Unplanned return emergency department (ED) visits can reflect clinical deterioration or unmet need from the original visit. We determined the characteristics and outcomes of patients with COVID-19 who return to the ED for COVID-19-related revisits.

METHODS

This retrospective observational study used data for all adult patients visiting 47 Canadian EDs with COVID-19 between 1 March 2020 and 31 March 2022. Multivariable logistic regression assessed the characteristics associated with having a no return visit (SV=single visit group) versus at least one return visit (MV=return visit group) after being discharged alive at the first ED visit.

RESULTS

39 809 patients with COVID-19 had 44 862 COVID-19-related ED visits: 35 468 patients (89%) had one visit (SV group) and 4341 (11%) returned to the ED (MV group) within 30 days (mean 2.2, SD=0.5 ED visit). 40% of SV patients and 16% of MV patients were admitted at their first visit, and 41% of MV patients not admitted at their first ED visit were admitted on their second visit. In the MV group, the median time to return was 4 days, 49% returned within 72 hours. In multivariable modelling, a repeat visit was associated with a variety of factors including older age (OR=1.25 per 10 years, 95% CI (1.22 to 1.28)), pregnancy (1.86 (1.46 to 2.36)) and presence of comorbidities (eg, 1.72 (1.40 to 2.10) for cancer, 2.01 (1.52 to 2.66) for obesity, 2.18 (1.42 to 3.36) for organ transplant), current/prior substance use, higher temperature or WHO severe disease (1.41 (1.29 to 1.54)). Return was less likely for females (0.82 (0.77 to 0.88)) and those boosted or fully vaccinated (0.48 (0.34 to 0.70)).

CONCLUSIONS

Return ED visits by patients with COVID-19 within 30 days were common during the first two pandemic years and were associated with multiple factors, many of which reflect known risk for worse outcomes. Future studies should assess reasons for revisit and opportunities to improve ED care and reduce resource use.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, NCT04702945.

Determinants of SARS-CoV-2 IgG response and decay in Canadian healthcare workers: A prospective cohort study

INTRODUCTION

Healthcare workers (HCWs) from an interprovincial Canadian cohort gave serial blood samples to identify factors associated with anti-receptor binding domain (anti-RBD) IgG response to the SARS-CoV-2 virus.

METHODS

Members of the HCW cohort donated blood samples four months after their first SARS-CoV-2 immunization and again at 7, 10 and 13 months. Date and type of immunizations and dates of SARS-CoV-2 infection were collected at each of four contacts, together with information on immunologically-compromising conditions and current therapies. Blood samples were analyzed centrally for anti-RBD IgG and anti-nucleocapsid IgG (Abbott Architect, Abbott Diagnostics). Records of immunization and SARS-CoV-2 testing from public health agencies were used to assess the impact of reporting errors on estimates from the random-effects multivariable model fitted to the data.

RESULTS

2752 of 4567 vaccinated cohort participants agreed to donate at least one blood sample. Modelling of anti-RBD IgG titer from 8903 samples showed an increase in IgG with each vaccine dose and with first infection. A decrease in IgG titer was found with the number of months since vaccination or infection, with the sharpest decline after the third dose. An immunization regime that included mRNA1273 (Moderna) resulted in higher anti-RBD IgG. Participants reporting multiple sclerosis, rheumatoid arthritis or taking selective immunosuppressants, tumor necrosis factor inhibitors, calcineurin inhibitors and antineoplastic agents had lower anti-RBD IgG. Supplementary analyses showed higher anti-RBD IgG in those reporting side-effects of vaccination, no relation of anti-RBD IgG to obesity and lower titers in women immunized in early or mid-pregnancy. Sensitivity analysis results suggested no important bias in the self-report data.

CONCLUSION

Creation of a prospective cohort was central to the credibility of results presented here. Serial serology assessments, with longitudinal analysis, provided effect estimates with enhanced accuracy and a clearer understanding of medical and other factors affecting response to vaccination.

Factors Associated with COVID-19 Vaccine Uptake Among High School Students in a Large, Diverse Metropolitan Area

BACKGROUND

Because previous studies on adolescent COVID-19 attitudes focused on intent to get vaccinated, this study examined attitudinal factors and racial/ethnic differences associated with vaccine uptake.

METHODS

In a cross-sectional survey of a metropolitan high school district, students were asked about their COVID-19 attitudes, information sources, and whether they had been vaccinated. Logistic regression predicted vaccination status and adjusted odds ratios (aOR) controlled for race/ethnicity.

RESULTS

Being unvaccinated was associated with themes of distrust with concerns about vaccine newness (aOR: 0.10; 95% confidence intervals [CI]: 0.06-0.15), side effects (aOR: 0.22; 95% CI: 0.15-0.33), efficacy (aOR: 0.25; 95% CI: 0.17-0.38), distrust of vaccines (aOR: 0.16; 95% CI: 0.09-0.27), government oversight (aOR: 0.19; 95% CI: 0.13-0.30), and politicization (aOR: 0.60; 95% CI: 0.41-0.88). Vaccine uptake was influenced by official information sources, school closures, and vaccine availability. The majority of vaccinated and unvaccinated students trusted primary care professionals as a source for COVID-19 information, but their influence varied across race/ethnic groups.

CONCLUSIONS

Trust and distrust were the main themes of vaccinated and unvaccinated students, respectively. Incorporating trusted information sources (primary care professionals) in information dissemination efforts may improve vaccine uptake.

Immune escape and waning immunity of COVID-19 monovalent mRNA vaccines against symptomatic infection with BA.1/BA.2 and BA.5 in Japan

BACKGROUND

Repeated emergence of variants with immune escape capacity and waning immunity from vaccination are major concerns for COVID-19. We examined whether the surge in Omicron subvariant BA.5 cases was due to immune escape or waning immunity through vaccine effectiveness (VE) evaluation.

METHODS

A test-negative case-control study was conducted in 16 clinics/hospitals during the BA.1/BA.2-dominant and BA.5-dominant periods. VE against symptomatic infection was estimated after adjusting for age, sex, comorbidity, occupation, testing frequency, prior infection, close contact history, clinic/hospital, week, and preventive measures. Absolute VE (aVE) was calculated for 2/3/4 doses, compared to the unvaccinated. Relative VE (rVE) was calculated, comparing 3 vs 2 and 4 vs 3 doses.

RESULTS

13,025 individuals were tested during the BA.1/BA.2-dominant and BA.5-dominant periods with similar baseline characteristics. For BA.1/BA.2, aVE was 52 % (95 %CI:34-66) 14 days-3 months post-dose 2, 42 % (29-52) > 6 months post-dose 2, 71 % (64-77) 14 days-3 months post-dose 3, and 68 % (52-79) 3-6 months post-dose 3. rVE was 49 % (38-57) 14 days-3 months post-dose 3 and 45 % (18-63) 3-6 months post-dose 3. For BA.5, aVE was 56 % (27-73) 3-6 months post-dose 2, 32 % (12-47) > 6 months post-dose 2, 70 % (61-78) 14 days-3 months post-dose 3, 59 % (48-68) 3-6 months post-dose 3, 50 % (29-64) > 6 months post-dose 3, and 74 % (61-83) ≥ 14 days post-dose 4. rVE was 56 % (45-65) 14 days-3 months post-dose 3, 39 % (27-48) 3-6 months post-dose 3, 25 % (-2-45) > 6 months post-dose 3, and 30 % (-6-54) ≥ 14 days post-dose 4.

CONCLUSIONS

Booster doses initially provided high protection against BA.5 at a level similar to that against BA.1/BA.2. However, the protection seemed shorter-lasting against BA.5, which likely contributed to the surge. Furthermore, rVE post-dose 4 was low even among recent vaccinees. These results support the introduction of variant-containing vaccines and emphasize the need for vaccines with longer duration of protection.