COVID-19 vaccines and adverse events of special interest: A multinational Global Vaccine Data Network (GVDN) cohort study of 99 million vaccinated individuals

BACKGROUND

The Global COVID Vaccine Safety (GCoVS) Project, established in 2021 under the multinational Global Vaccine Data Network™ (GVDN®), facilitates comprehensive assessment of vaccine safety. This study aimed to evaluate the risk of adverse events of special interest (AESI) following COVID-19 vaccination from 10 sites across eight countries.

METHODS

Using a common protocol, this observational cohort study compared observed with expected rates of 13 selected AESI across neurological, haematological, and cardiac outcomes. Expected rates were obtained by participating sites using pre-COVID-19 vaccination healthcare data stratified by age and sex. Observed rates were reported from the same healthcare datasets since COVID-19 vaccination program rollout. AESI occurring up to 42 days following vaccination with mRNA (BNT162b2 and mRNA-1273) and adenovirus-vector (ChAdOx1) vaccines were included in the primary analysis. Risks were assessed using observed versus expected (OE) ratios with 95 % confidence intervals. Prioritised potential safety signals were those with lower bound of the 95 % confidence interval (LBCI) greater than 1.5.

RESULTS

Participants included 99,068,901 vaccinated individuals. In total, 183,559,462 doses of BNT162b2, 36,178,442 doses of mRNA-1273, and 23,093,399 doses of ChAdOx1 were administered across participating sites in the study period. Risk periods following homologous vaccination schedules contributed 23,168,335 person-years of follow-up. OE ratios with LBCI > 1.5 were observed for Guillain-Barré syndrome (2.49, 95 % CI: 2.15, 2.87) and cerebral venous sinus thrombosis (3.23, 95 % CI: 2.51, 4.09) following the first dose of ChAdOx1 vaccine. Acute disseminated encephalomyelitis showed an OE ratio of 3.78 (95 % CI: 1.52, 7.78) following the first dose of mRNA-1273 vaccine. The OE ratios for myocarditis and pericarditis following BNT162b2, mRNA-1273, and ChAdOx1 were significantly increased with LBCIs > 1.5.

CONCLUSION

This multi-country analysis confirmed pre-established safety signals for myocarditis, pericarditis, Guillain-Barré syndrome, and cerebral venous sinus thrombosis. Other potential safety signals that require further investigation were identified.

Prospective monitoring of adverse events following vaccination with Modified vaccinia Ankara - Bavarian Nordic (MVA-BN) administered to a Canadian population at risk of Mpox: A Canadian Immunization Research Network study

MVA-BN is an orthopoxvirus vaccine that provides protection against both smallpox and mpox. In June 2022, Canada launched a publicly-funded vaccination campaign to offer MVA-BN to at-risk populations including men who have sex with men (MSM) and sex workers. The safety of MVA-BN has not been assessed in this context. To address this, the Canadian National Vaccine Safety Network (CANVAS) conducted prospective safety surveillance during public health vaccination campaigns in Toronto, Ontario and in Vancouver, British Columbia. Vaccinated participants received a survey 7 and 30 days after each MVA-BN dose to elicit adverse health events. Unvaccinated individuals from a concurrent vaccine safety project evaluating COVID-19 vaccine safety were used as controls. Vaccinated and unvaccinated participants that reported a medically attended visit on their 7-day survey were interviewed. Vaccinated participants and unvaccinated controls were matched 1:1 based on age group, gender, sex and provincial study site. Overall, 1,173 vaccinated participants completed a 7-day survey, of whom 75 % (n = 878) also completed a 30-day survey. Mild to moderate injection site pain was reported by 60 % of vaccinated participants. Among vaccinated participants 8.4 % were HIV positive and when compared to HIV negative vaccinated individuals, local injection sites were less frequent in those with HIV (48 % vs 61 %, p = 0.021), but health events preventing work/school or requiring medical assessment were more frequent (7.1 % vs 3.1 %, p = 0.040). Health events interfering with work/school, or requiring medical assessment were less common in the vaccinated group than controls (3.3 % vs. 7.1 %, p < 0.010). No participants were hospitalized within 7 or 30 days of vaccination. No cases of severe neurological disease, skin disease, or myocarditis were identified. Our results demonstrate that the MVA-BN vaccine appears safe when used for mpox prevention, with a low frequency of severe adverse events and no hospitalizations observed.

Background rates of adverse events of special interest for COVID-19 vaccines: A multinational Global Vaccine Data Network (GVDN) analysis

BACKGROUND

The Global COVID Vaccine Safety (GCoVS) project was established in 2021 under the multinational Global Vaccine Data Network (GVDN) consortium to facilitate the rapid assessment of the safety of newly introduced vaccines. This study analyzed data from GVDN member sites on the background incidence rates of conditions designated as adverse events of special interest (AESI) for COVID-19 vaccine safety monitoring.

METHODS

Eleven GVDN global sites obtained data from national or regional healthcare databases using standardized methods. Incident events of 13 pre-defined AESI were included for a pre-pandemic period (2015-19) and the first pandemic year (2020). Background incidence rates (IR) and 95% confidence intervals (CI) were calculated for inpatient and emergency department encounters, stratified by age and sex, and compared between pre-pandemic and pandemic periods using incidence rate ratios.

RESULTS

An estimated 197 million people contributed 1,189,652,926 person-years of follow-up time. Among inpatients in the pre-pandemic period (2015-19), generalized seizures were the most common neurological AESI (IR ranged from 22.15 [95% CI 19.01-25.65] to 278.82 [278.20-279.44] per 100,000 person-years); acute disseminated encephalomyelitis was the least common (<0.5 per 100,000 person-years at most sites). Pulmonary embolism was the most common thrombotic event (IR 45.34 [95% CI 44.85-45.84] to 93.77 [95% CI 93.46-94.08] per 100,000 person-years). The IR of myocarditis ranged from 1.60 [(95% CI 1.45-1.76) to 7.76 (95% CI 7.46-8.08) per 100,000 person-years. The IR of several AESI varied by site, healthcare setting, age and sex. The IR of some AESI were notably different in 2020 compared to 2015-19.

CONCLUSION

Background incidence of AESIs exhibited some variability across study sites and between pre-pandemic and pandemic periods. These findings will contribute to global vaccine safety surveillance and research.

Vaccine acceptance, hesitancy and refusal in Canada: Challenges and potential approaches

"Vaccine hesitancy" is a concept used frequently in vaccination discourse and is challenging previously held perspective that individual vaccination attitudes and behaviours are a simple dichotomy of accept or reject. Given the importance of achieving high vaccine coverage in Canada to avoid vaccine preventable diseases and their consequences, vaccine hesitancy is an important issue that needs to be addressed. This article describes the scope and causes of vaccine hesitancy in Canada and proposes potential approaches to address it.

Intention of parents to have male children vaccinated with the human papillomavirus vaccine

BACKGROUND

Although already approved for use in males in some jurisdictions, there is little information about parental attitudes toward having their sons receive the human papillomavirus (HPV) vaccine. The goal of this study was to ascertain parental intentions to vaccinate their sons with an HPV vaccine and to determine factors that predict this intention.

METHODS

Parents of children aged 8-18 years were recruited from across Canada through random digit dialling. Participants were asked to respond to a series of questions in the context of a Grade 6 (age 11/12 years old), publicly funded school-based HPV vaccine programme, including their intention to vaccinate their sons with the HPV vaccine. Parents were also asked about a series of characteristics thought to predict intention to vaccinate as well as demographic characteristics. Backwards logistic regression was conducted to calculate adjusted odds ratios (AOR) to identify the factors that are predictive of parents' intention to vaccinate their son(s) against HPV.

RESULTS

Of the 1381 respondents with male children, 67.8% (95% CI 65.3 to 70.3) intend to vaccinate their son(s) against HPV. Parents who had positive attitudes toward vaccines and the HPV vaccine in particular (AOR 41.5, 95% CI 9.5 to 181.7), parents who were influenced by subjective norms (AOR 7.8, 95% CI 5.8 to 10.5), parents who felt that the vaccine had limited influence on sexual behaviour (AOR 2.3, 95% CI 1.6 to 3.3) and parents who were aware of HPV (AOR 1.4, 95% CI 1.1 to 2.0) were significantly more likely to report an intention to vaccinate boys against HPV. In contrast, residence in British Columbia compared to Atlantic Canada (AOR 0.4, 95% CI 0.2 to 0.8) and higher education (AOR 0.7, 95% CI 0.5 to 0.9) were negatively associated with intention to vaccinate. Parents who reported an intention to vaccinate their daughters were also highly likely to report an intention to vaccinate their sons (kappa = 0.9, p<0.001).

DISCUSSION

The majority of Canadian parents would intend to have their male children receive the HPV vaccine in the context of a publicly funded school-based immunisation programme. Overall attitudes toward vaccine, recommendations from health professionals and impact of the vaccine on sexual practices are important predictors of intention to have a male child receive the HPV vaccine.

Health behavior associated with influenza vaccination among healthcare workers in long-term-care facilities

OBJECTIVE

To investigate the health behavior associated with influenza vaccination among healthcare workers (HCWs) in long-term-care facilities.

DESIGN

A cross-sectional, self-administered survey of HCWs, augmented with focus groups to further examine attitudes toward influenza vaccination.

SETTING

Two long-term-care facilities participated in the survey. The focus groups were held at one of the two facilities.

PARTICIPANTS

All HCWs were invited to participate in the survey and all nonmanagerial staff members were invited to participate in the focus groups. The response rate for the survey was 58% (231 of 401).

RESULTS

Vaccinated HCWs had a more positive attitude toward influenza vaccination and a greater belief that the vaccine is effective. This was not accompanied by differences in vaccine knowledge or values of potential preventive outcomes. Nonvaccinated respondents were more likely to believe that other preventive measures, such as washing hands, taking vitamins and supplements, eating a nutritious diet, exercising, and taking homeopathic or naturopathic medications, were more effective than vaccination. Additional findings from the focus groups suggest that HCWs believe that the main purpose of influenza vaccination programs is to protect residents' health at the expense, potential harm, and burden of responsibility of the staff.

CONCLUSIONS

This study identifies challenges to and opportunities for improving vaccination rates among HCWs. A message that emphasizes the health benefits of vaccination to staff members, such as including vaccination as part of a staff "wellness" program, may improve the credibility of influenza immunization programs and coverage rates.

Prevention of influenza and pneumococcal pneumonia in Canadian long-term care facilities: how are we doing?

BACKGROUND

Influenza and pneumococcal pneumonia are serious health problems among elderly people and a major cause of death in long-term care facilities. We describe the results of serial surveys of vaccination coverage and influenza outbreak management in Canadian long-term care facilities over the last decade.

METHODS

Cross-sectional surveys consisting of questionnaires mailed to all Canadian residential long-term care facilities for elderly people in 1991 and to a random sample of respondents in 1995 and 1999.

RESULTS

The response rates were 83% (430/515) in 1995 and 75% (380/506) in 1999. In 1999 the mean reported rates of influenza vaccination were 83% among residents and 35% among staff, and the mean rate of pneumococcal vaccination among residents was 71%; all 3 rates were significantly higher than those in 1991. The rates were also higher in facilities with an infection control practitioner than in those without such an individual (88% v. 82% for influenza vaccination among residents [p < 0.001], 42% v. 35% for influenza vaccination among staff [p = 0.008] and 75% v. 63% for pneumococcal vaccination among residents [p < 0.001]). Obtaining consent for vaccination on admission to the facility was associated with higher influenza and pneumococcal vaccination rates among residents (p = 0.04 and p < 0.001 respectively). Facilities with higher influenza vaccination rates among residents and staff reported lower rates of influenza outbreaks (p = 0.08 and 0.03 respectively). Despite recommendations from the National Advisory Committee on Immunization, only 50% of the facilities had policies for amantadine prophylaxis during influenza A outbreaks. Amantadine was judged effective in controlling 76% of the influenza A outbreaks and was discontinued because of side effects in 3% of the residents.

INTERPRETATION

Influenza and pneumococcal vaccination rates among residents and staff in Canadian long-term care facilities have increased over the last decade but remain suboptimal. Vaccination of residents and staff against influenza is associated with a reduced risk of influenza outbreaks. Amantadine is effective in controlling influenza outbreaks in long-term care facilities.

Expanding the epidemiologic profile: risk factors for active tuberculosis in people immigrating to Ontario

BACKGROUND

Many people immigrating to Canada come from countries with a high burden of tuberculosis. The aim of this study was to develop a detailed epidemiologic profile of foreign-born people with tuberculosis living in Ontario.

METHODS

In this population-based case-control study, cases of tuberculosis diagnosed in 1994-1995 were identified from the database of the Ontario Reportable Disease Information Service and were considered eligible for analysis if a record of landing (receipt of permission to establish residence in Canada) from the period 1986-1995 was found in the Citizenship and Immigration Canada (CIC) database, if the person was at least 11 years of age at the time their visa was issued, and if the person had not been diagnosed with tuberculosis before becoming legally landed in Canada. Control subjects, who met the same criteria as the case subjects but who did not have tuberculosis in 1994-1995, were identified from a CIC database for landed immigrants.

RESULTS

A total of 1341 cases of tuberculosis in foreign-born people were reported in Ontario in 1994-1995. A record of landing was found in CIC databases for 1099 of these people, 224 of whom were not legally landed at the time of diagnosis. In total, 602 cases met the inclusion criteria. The 2 strongest determinants of risk among those who had become landed within the preceding 10 years were referral for medical surveillance by immigration officials (odds ratio [OR] 3.8, 95% confidence interval [CI] 2.6-6.0) and world region of origin (Somalia [OR 67.7, 95% CI 31.3-154.9], Vietnam [OR 25.0, 95% CI 12.5-50.0], the Philippines [OR 11.9, 95% CI 6.0-23.3], other sub-Saharan African countries [OR 11.6, 95% CI 5.7-23.2], India [OR 9.7, 95% CI 4.9-18.9], China [OR 6.1, 95% CI 3.1-12.1], other Asian countries [OR 4.7, 95% CI 2.4-9.1], the Middle East [OR 4.1, 95% CI 2.0-8.3], Latin America [OR 1.9, 95% CI 0.9-3.8), and the former socialist countries of Europe [OR 1.8, 95% CI 0.8-3.8]; the reference category was countries with established market economies). Low socioeconomic status was an independent risk factor.

INTERPRETATION

The risk of tuberculosis in groups of people migrating to Ontario is highly variable and is influenced by several factors. Successful population-based tuberculosis prevention strategies will need to accommodate this variability.

Protection after two doses of measles vaccine is independent of interval between doses

The protection provided by one or two doses of measles vaccine was compared, as was the effect of the timing of delivery of the doses on the protection provided. A total of 5542 measles cases occurred in Ontario, Canada, between January 1990 and December 1996. Three controls per case were matched for age and residence. Children who received a single dose at age 15 months and older were 5 times more likely to contract measles than were children who received two doses of vaccine after their first birthday. Among children given two doses of vaccines, the risk of measles was 3 times greater in those who had their first vaccination at age 11 months compared with children who first received vaccine after age 1 year, but the protection was independent of the interval between doses. Delaying the second dose >6 months after the first does not increase protection.

Outcome of pulmonary tuberculosis treatment in the tertiary care setting--Toronto 1992/93. Tuberculosis Treatment Completion Study Group

BACKGROUND

Completion of treatment of active cases of tuberculosis (TB) is the most important priority of TB control programs. This study was carried out to assess treatment completion for active cases of pulmonary TB in Toronto.

METHODS

Consecutive cases of culture-proven pulmonary TB were obtained from the microbiology laboratories of 5 university-affiliated tertiary care centres in Toronto in 1992/93. A standard data-collection tool was used to abstract information from inpatient and outpatient charts. For patients who were transferred to other treatment centres or lost to follow-up, the local health unit was contacted for information about treatment completion. If incomplete information was obtained from these sources, data from the provincial Reportable Disease Information System were also reviewed. The main outcome analysed was treatment outcome, with cases classified as completed (record of treatment completion noted), transferred (patient transferred to another centre but no treatment results available), defaulted (record of defaulting in patient chart but no record of treatment completion elsewhere, or patient still receiving treatment more than 15 months after diagnosis) or dead (patient died before treatment completion).

RESULTS

Of the 145 patients 84 (58%) completed treatment, 25 (17%) died, 22 (15%) defaulted and 14 (10%) were transferred. The corresponding values for the 22 patients with HIV coinfection were 6 (27%), 5 (23%), 8 (36%) and 3 (14%). Independent predictors of failure to complete treatment were injection drug use (adjusted odds ratio [OR] 5.7, 95% confidence interval [CI] 1.5 to 22.0), HIV infection (adjusted OR 4.6, 95% CI 1.4 to 14.7) and adverse drug reaction (adjusted OR 2.9, 95% CI 1.1 to 7.9). Independent predictors of death included age more than 50 years (adjusted OR 16.7, 95% CI 2.6 to 105.1), HIV infection (adjusted OR 16.1, 95% CI 3.9 to 66.4), immunosuppressive therapy (adjusted OR 8.0, 95% CI 1.9 to 34.4) and infection with a multidrug-resistant organism (adjusted OR 30.7, 95% CI 1.5 to 623.0).

INTERPRETATION

Treatment completion rates in tertiary care hospitals in Toronto in 1992/93 were below the rate recommended by the World Health Organization. Careful surveillance of treatment completion is necessary for the management of TB in metropolitan centres in Canada.

Vaccine storage and handling. Knowledge and practice in primary care physicians' offices

OBJECTIVE

To assess the knowledge and practice of vaccine storage and handling in primary care physicians' offices.

DESIGN

A cross-sectional study was conducted from August to December 1992. Staff responsible for vaccine storage were interviewed about their knowledge and practices of vaccine handling and storage. Refrigerators were inspected to document refrigerator temperature and vaccine storage conditions.

SETTING

General and pediatric practices in 12 regions of Ontario.

PARTICIPANTS

Practices outside metropolitan Toronto were selected by choosing every 10th physician who ordered vaccine from the local health department in 1992. Practices chosen in metropolitan Toronto were a random selection of physicians affiliated with a Toronto teaching hospital. Eighteen pediatric and 138 general practices were approached to participate; 12 pediatric and 123 general practices participated in the study. The overall response rate was 86.5%.

MAIN OUTCOME MEASURES

Survey responses and temperature and storage conditions of refrigerators upon inspection.

RESULTS

Fewer than seven (6%) practices answered all questions related to vaccine storage and handling correctly, and only 11 (10%) refrigerators had thermometers. One-third of refrigerators had temperatures outside the recommended range of 2 degrees C to 8 degrees C. Older refrigerators were more likely to have inappropriate temperatures than newer ones.

CONCLUSIONS

Knowledge and practice of vaccine storage and handling are often inadequate in primary care physicians' offices.

Tuberculosis surveillance practices in long-term care institutions

OBJECTIVES

To identify the tuberculosis (TB) skin-testing practices of long-term care facilities for the elderly in Toronto, Ontario.

DESIGN

A telephone survey using a 25-item questionnaire.

SETTING

Twenty-nine nursing homes (NHs) and 26 Homes for the Aged (HFAs) in metropolitan Toronto.

RESULTS

Thirty-one percent of facilities (17 of 55) had no formal tuberculin skin-testing program, including 52% of NHs (15 of 29) versus 8% of HFAs (2 of 26; P = 0.001). Ninety-two percent of HFAs (24 of 26), compared with 45% of NHs (13 of 29), obtained preadmission or admission skin-test status of residents (P = 0.0005). Annual testing was performed at 46% of HFAs (12 of 26) and 27% of NHs (8 of 29; P = 0.28). Of facilities that carried out any skin testing, 64% of HFAs (16 of 25) versus 32% of NHs (6 of 19) measured induration to establish test positivity (P = 0.068). Fifty-two percent of HFAs (13 of 25), compared with 21% of NHs (4 of 19), recorded the actual size of induration in the patient record (P = 0.085). Only 28% of HFAs (7 of 25) and 21% of NHs (4 of 19) correctly defined a positive tuberculin skin test.

CONCLUSIONS

TB surveillance practices in long-term care institutions in Toronto are inadequate and often yield results that do not predict the risk of infection and cannot be used to investigate outbreaks. Tuberculin skin-testing practices were better at HFAs, which are subject to provincial legislation regarding TB surveillance, than at NHs, which are not subject to this legislation. Staff at HFAs and NHs require education regarding tuberculin skin-testing policies and procedures.

Occupational exposure to Mycobacterium bovis infection in deer and elk in Ontario

In late 1991, two herds of deer and elk were depopulated at a slaughtering plant in Ontario, followed by processing of infected animals at a rendering plant. We conducted a questionnaire plus tuberculin skin-test survey of 104 exposed slaughtering and rendering plant workers, and government veterinarians and inspectors. Overall, 17 participants were skin-test positive, one of 51 initially skin-test negative subjects tested a second time three months later became positive, consistent with the risk associated with occupational exposure during the depopulation of tuberculous elk previously observed in Alberta. Deer farming is widespread, with 263 herds in Ontario. The likely route of transmission is through aerosols. Possible reasons for the low conversion rate include the use of respiratory protection, absence of a tanning plant, an enclosed rendering plant process, and late skin testing which may have underestimated the number of conversions. Recommendations for prevention are summarized; in particular, respiratory protection for work with infected herds should probably include high efficiency particulate face masks.

Partner notification for sexually transmitted diseases: proposed practice guidelines

Using the results of an analysis of available scientific evidence and a survey of current practice in Canada, as well as expert opinion, these guidelines attempt to consider current partner notification practice in Canada and recommend an approach to determining practice which is flexible enough to address local circumstances. Priority areas for future research were also identified.

A survey of public health partner notification for sexually transmitted diseases in Canada

OBJECTIVE

To describe the range of practice for sexually transmitted disease (STD) contact tracing/partner notification (PN) by public health agencies in Canada.

METHODS

A two-level mailed survey, using two different questionnaires, was conducted from Aug. 1991 to Feb. 1992, directed to: 1) provincial and territorial epidemiologists/directors of STD control, asking about program organization; and 2) 154 local health units/provincially run PN programs, asking about practice patterns of STD partner notification.

CONCLUSIONS

In Canada, STD PN by public health agencies is routinely practised in most provinces. PN efforts vary by the STD; less PN effort goes to chlamydia despite a high burden of illness; HIV PN is frequently perceived to be within the responsibility of the physician. For STDs with higher PN effort, the preferred method is provider referral. Targeting is seldom utilized, and there are little available data at a local level monitoring even process measures of effectiveness.

Partner notification for sexually transmitted diseases: an overview of the evidence

OBJECTIVE

To compare the effectiveness of alternative partner notification strategies for gonorrhea, chlamydia, syphilis, HIV and hepatitis B.

DATA SOURCES

Studies were identified using MEDLINE, EMBASE, SCISEARCH and other databases, review of reference lists and personal contact with over 80 international experts.

STUDY SELECTION

Studies with at least two comparison groups exposed to different partner notification strategies were included.

DATA EXTRACTION

Methodological rigor was assessed, and information regarding study populations, interventions and outcomes was extracted independently by two reviewers.

MAIN RESULTS

Twelve studies met our inclusion criteria; five were methodologically strong; seven provided data on the referral process; four provided data on trained interviewers compared with routine care providers; and three provided data on the interview process.

CONCLUSIONS

Only limited, broad conclusions regarding the effectiveness of various partner notification approaches could be drawn from these comparative studies. Until newer data become available, practice guidelines must be based to a large extent on other grounds.