Factors associated with SARS-CoV-2 infection in unvaccinated children and young adults.

BACKGROUND AND OBJECTIVES: Pediatric COVID-19 cases are often mild or asymptomatic, which has complicated estimations of disease burden using existing testing practices. We aimed to determine the age-specific population seropositivity and risk factors of SARS-CoV-2 seropositivity among children and young adults during the pandemic in British Columbia (BC). METHODS: We conducted two cross-sectional serosurveys: phase 1 enrolled children and adults < 25 years between November 2020-May 2021 and phase 2 enrolled children < 10 years between June 2021-May 2022 in BC. Participants completed electronic surveys and self-collected finger-prick dried blood spot (DBS) samples. Samples were tested for immunoglobulin G antibodies against ancestral spike protein (S). Descriptive statistics from survey data were reported and two multivariable analyses were conducted to evaluate factors associated with seropositivity. RESULTS: A total of 2864 participants were enrolled, of which 95/2167 (4.4%) participants were S-seropositive in phase 1 across all ages, and 61/697 (8.8%) unvaccinated children aged under ten years were S-seropositive in phase 2. Overall, South Asian participants had a higher seropositivity than other ethnicities (13.5% vs. 5.2%). Of 156 seropositive participants in both phases, 120 had no prior positive SARS-CoV-2 test. Young infants and young adults had the highest reported seropositivity rates (7.0% and 7.2% respectively vs. 3.0-5.6% across other age groups). CONCLUSIONS: SARS-CoV-2 seropositivity among unvaccinated children and young adults was low in May 2022, and South Asians were disproportionately infected. This work demonstrates the need for improved diagnostics and reporting strategies that account for age-specific differences in pandemic dynamics and acceptability of testing mechanisms.

Adverse Events Following Immunization With mRNA and Viral Vector Vaccines in Individuals With Previous Severe Acute Respiratory Syndrome Coronavirus 2 Infection From the Canadian National Vaccine Safety Network.

BACKGROUND: Adults previously infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) develop short-term immunity and may have increased reactogenicity to coronavirus disease 2019 (COVID-19) vaccines. This prospective, multicenter, active-surveillance cohort study examined the short-term safety of COVID-19 vaccines in adults with a prior history of SARS-CoV-2. METHODS: Canadian adults vaccinated between 22 December 2020 and 27 November 2021 were sent an electronic questionnaire 7 days post-dose 1, dose 2, and dose 3 vaccination. The main outcome was health events occurring in the first 7 days after each vaccination that prevented daily activities, resulted in work absenteeism, or required a medical consultation, including hospitalization. RESULTS: Among 684 998 vaccinated individuals, 2.6% (18 127/684 998) reported a prior history of SARS-CoV-2 infection a median of 4 (interquartile range: 2-6) months previously. After dose 1, individuals with moderate (bedridden) to severe (hospitalized) COVID-19 who received BNT162b2, mRNA-1273, or ChAdox1-S vaccines had higher odds of a health event preventing daily activities, resulting in work absenteeism or requiring medical consultation (adjusted odds ratio [95% confidence interval]: 3.96 [3.67-4.28] for BNT162b2, 5.01 [4.57-5.50] for mRNA-1273, and 1.84 [1.54-2.20] for ChAdox1-S compared with no infection). Following dose 2 and 3, the greater risk associated with previous infection was also present but was attenuated compared with dose 1. For all doses, the association was lower or absent after mild or asymptomatic infection. CONCLUSIONS: Adults with moderate or severe previous SARS-CoV-2 infection were more likely to have a health event sufficient to impact routine activities or require medical assessment in the week following each vaccine dose.

Antibiotic use in children hospitalised for influenza, 2010-2021: the Canadian Immunization Monitoring Program Active (IMPACT).

PURPOSE: To determine characteristics associated with inappropriate antibiotic use amongst children hospitalised for influenza. METHODS: We performed active surveillance for laboratory-confirmed influenza hospitalizations amongst children ≤ 16 years old at the 12 Canadian Immunization Monitoring Program Active hospitals, from September 2010 to August 2021. Antibiotic use was presumed appropriate if any of the following indications were met: age < 1 month, immunocompromised, hemoglobinopathy, laboratory-confirmed bacterial infection, radiographically confirmed pneumonia, admission to an intensive care unit and mechanical ventilation. Regression analyses were used to identify baseline and clinical characteristics associated with antibiotic use amongst patients without an appropriate indication. RESULTS: Amongst 8971 children, 6424 (71.6%) received any antibiotics during their hospitalisation. Amongst the 4429 children without an appropriate indication, 2366 (53.2%) received antibiotics. Antibiotic use amongst children without appropriate indication differed between study centres, ranging from 33.2% to 66.1% (interquartile range [IQR] 50.6-56.3%); it did not change significantly over time (p-value for trend = 0.28). In multivariable analyses, older age (adjusted odds ratio [aOR] 0.97, 95% confidence interval [CI] 0.96-0.99), presence of any high-risk condition (aOR 0.80, 95% CI 0.70-0.92), influenza virus type B (aOR 0.8, 95% CI 0.70-0.91) and croup (aOR 0.64, 95% CI 0.49-0.83) were associated with less, whilst fever ≥ 38.5 °C (aOR 1.82, 95% CI 1.42-2.35) and hospitalisation duration (aOR 1.12, 95% CI 1.09-1.15) were associated with more inappropriate antibiotic use. CONCLUSIONS: Over two-third of children hospitalised for influenza received antibiotics, including over half of those without an appropriate indication for antibiotic treatment. Differences amongst study centres suggest the importance of contextual determinants of antibiotic use.

Parent and healthcare provider views of live varicella vaccination of pediatric solid organ transplant recipients.

BACKGROUND: Live attenuated varicella vaccine (LAVV) has historically been contraindicated in children who are immunocompromised due to solid organ transplant (SOT) because of safety concerns. Recently, clinical guidelines were developed that support post-transplant varicella vaccination in selected SOT recipients based on emerging evidence of LAVV safety. This qualitative study sought to explore barriers and facilitators to implementing the new guidelines, as well as acceptability of LAVV among healthcare providers (HCPs) and parents. METHODS: HCPs and parents of transplant recipients were recruited from four sites using purposive sampling. Data from semi-structured interviews were analyzed using an Interpretive Description approach that incorporated data from the interviews, academic knowledge and clinical experience, and drew from Grounded Theory and Thematic Analysis. The theoretical framework used was Adaptive Leadership. RESULTS: Thirty-four participants (16 HCPs and 18 parents) were included in the analysis. Parents developed skills in adaptive leadership that included strategies to protect their child against infectious diseases. Foundational information that live vaccines were absolutely contraindicated post-transplant "stuck" with parents and led them to develop strategies other than vaccination to keep their child safe. Some parents struggled to understand that information previously presented as a certainty (contraindication of LAVV) could change. Their approach to adaptive leadership informed their appraisal of the new vaccination guidelines and willingness to accept vaccination. CONCLUSIONS: HCPs should adopt a family-centered approach to communicating changing guidelines that considers parents' approach to adaptive leadership and discusses the changing nature of medical evidence. Trust between HCPs and parents can facilitate these conversations.

"Ultimately, the choice is theirs": Informed choice vaccine conversations and Canadian midwives.

BACKGROUND: In Canada, vaccination that protects against pertussis and influenza is recommended in every pregnancy, but uptake remains low. Communicating the risks and benefits of vaccination is key to clinical conversations about vaccination, which may influence the uptake of pregnancy and subsequent infant vaccines. Canadian midwives use an informed choice model of care, which is distinct from informed consent and prioritizes client autonomy in decision-making. METHODS: Using institutional ethnography, which treats lived experience as expertise, we aimed to understand how Canadian midwives, governed by intersecting professional standards and regulations, navigate vaccine discussions with their clients. We conducted interviews with individuals involved in midwifery training, regulation, and continuing education, as well as key public health professionals with expertise in immunization training. Following the phases of thematic analysis outlined by Braun and Clarke, data were analyzed holistically, emergent themes identified, and coding categories developed. RESULTS: Two types of confidence emerged as important to midwives' ability to conduct a thoroughly informed choice discussion about vaccines: confidence in vaccination itself (vaccine confidence), and confidence in vaccine knowledge and counseling skills (vaccine counseling confidence). A deferred or shortened vaccine discussion could be the result of either vaccine hesitancy or counseling hesitancy. DISCUSSION: Currently, available clinical communication tools and recommended techniques for addressing vaccine hesitancy do not always adapt well to the needs of midwives working to support clients' informed choice decisions. Our findings suggest that Canadian midwives require more and clearer resources on both the risks and benefits of vaccination in pregnancy.

Lessons learned from the experiences and perspectives of frontline healthcare workers on the COVID-19 response: a qualitative descriptive study.

BACKGROUND: During the COVID-19 pandemic, healthcare systems and healthcare workers (HCWs) faced significant demands and unique challenges. In this qualitative study, we explore the effects of the COVID-19 public health policies on British Columbia's frontline HCWs, describe what worked in the management of the pandemic, and elucidate the lessons learned that could be applied to future pandemic preparedness, recovery and response. METHODS: This qualitative descriptive study is part of a larger, national multi-case study on pandemic policy communication and uptake. Semi-structured interviews were conducted from November 2020- June 2021 with fourteen HCWs working in long-term care (LTC), acute care and public health settings. Data were inductively coded, and analyzed following a resilience framework for public health emergency preparedness, which emphasizes the essential elements of a public health system, vital to all phases of health emergency management, readiness, response and recovery. RESULTS: HCWs experienced confusion, frustration, uncertainty, anxiety, fatigue and stress, during the pandemic and detailed challenges that affected policy implementation. This included communication and coordination inconsistencies between the province and regional health authorities; lack of involvement of frontline staff in pandemic planning; inadequate training and support; inadequate personal protective equipment resource capacity and mobilization; and staffing shortages. HCWs recommended increased collaboration between frontline staff and policy makers, investment in preparing and practicing pandemic plans, and the need for training in emergency management and infection prevention and control. CONCLUSIONS: Pandemic planning, response and recovery should include inputs from actors/key stakeholders at the provincial, regional and local levels, to facilitate better coordination, communication and outcomes. Also, given the critical roles of frontline HCWs in policy implementation, they should be adequately supported and consideration must be given to how they interpret and act on policies. Bi-directional communication channels should be incorporated between policymakers and frontline HCWs to verify the appropriate adoption of policies, reflective learning, and to ensure policy limitations are being communicated and acted upon by policy makers.

Revaccination and Adverse Event Recurrence in Patients with Adverse Events following Immunization.

OBJECTIVES: To estimate the risk of recurrence of adverse events following immunization (AEFIs) upon revaccination and to determine among patients with suspected vaccine allergy whether allergy skin test positivity was associated with AEFI recurrence. STUDY DESIGN: This prospective observational study included patients assessed in the Canadian Special Immunization Clinic Network from 2013 to 2019 with AEFIs who required revaccination with the vaccine temporally associated with their AEFI. Participants underwent standardized assessment and data collection. Special Immunization Clinic physicians used guidelines to inform their recommendations. Participants were followed up after revaccination to capture AEFI recurrences. Data were transferred to a central database for descriptive analysis. RESULTS: Overall, 588 participants were assessed for 627 AEFIs; 570 (91%) AEFIs occurred in children <18 years of age. AEFIs included immediate hypersensitivity (130/627; 21%), large local reactions (110/627; 18%), nonurticarial rash (51/627; 8%), seizures (26/627; 4%), and thrombocytopenia (11/627; 2%). Revaccination was recommended to 513 of 588 (87%) participants. Among participants recommended and due for revaccination during the study period, 63% (299/477) were revaccinated. AEFI recurrence was 10% (31/299) overall, 31% (15/49) for large local reactions, and 7% (5/66) for immediate hypersensitivity. No recurrence was serious. Among 92 participants with suspected vaccine allergy who underwent skin testing and were revaccinated, the negative predictive value of skin testing for AEFI recurrence was 96% (95% CI 92.5%-99.5%). CONCLUSIONS: Most individuals with AEFIs were safely revaccinated. Among those with suspected vaccine allergy, skin testing may help determine the safety of revaccination.

Parents' perceptions on COVID-19 vaccination as the new routine for their children ≤ 11 years old.

Canadian children 5-11 years old became eligible for COVID-19 vaccination on November 19, 2021, with eligibility for younger children expected later. We aimed to descriptively assess parents' COVID-19 vaccine intentions and acceptability of future doses, including co-administration and annual vaccination for their children. We conducted a cross-sectional Canadian online survey of parents from October 14-November 12, 2021, just prior to authorization of the pediatric formulation of the BNT162b2 COVID-19 vaccine for children aged 5-11 years. We assessed parents' intention to vaccinate their children aged 5-11 years, 2-4 years, and 6-23 months; reasons for their intention; and preferences for delivery and access to vaccines. Of 1129 parents, 56% intended to vaccinate their child aged 5-11 years against COVID-19; intentions were lower for children aged 6-23 months (41.9%) and 2-4 years (45.4%). Most parents who intended to vaccinate supported co-administration with routine (61.1%) or influenza (55.4%) vaccines, administration at school (63.6%), receipt of booster doses of COVID-19 vaccine (57.8%), and annual vaccination (56.4%) for their child. Despite parents' high COVID-19 vaccination uptake for themselves (88.8%), intentions for children aged 5-11 years was low. Currently, 56.9% of Canadian children aged 5-11 years have received one dose of a COVID-19 vaccine, and only 37.1% are fully vaccinated. Given that intentions for children <5 years was lower than those 5-11 years, we can also expect low uptake in this group. Parents' preferences regarding delivery and access to COVID-19 vaccination should be considered by public health officials when planning vaccination strategies for children.

Is the pre-natal period a missed opportunity for communicating with parents about immunizations? Evidence from a longitudinal qualitative study in Victoria, British Columbia.

BACKGROUND: Growing evidence shows that many parents begin the decision-making process about infant vaccination during pregnancy and these decisions - once established - may be resistant to change. Despite this, many interventions targeting vaccination are focused on communicating with parents after their baby is born. This suggests that the prenatal period may constitute a missed opportunity for communicating with expectant parents about infant vaccination. METHODS: Using a longitudinal qualitative design, we conducted two interviews (prepartum and postpartum) with women (n = 19) to explore the optimal timing of vaccination information. The data were analyzed thematically, and examined across all sets of pre- and post-partum interviews as well as within each individual participant to draw out salient themes. RESULTS: Most participants formed their intentions to vaccinate before the baby was born and indicated that they would welcome information about vaccination from their maternity care providers. However, few individuals recalled their maternity care providers initiating vaccination-related conversations with them. CONCLUSION: The prenatal period is an important time to begin conversations with expectant parents about vaccinating their infants, particularly if these conversations are initiated by trusted maternity care providers. More information is needed on how maternity care providers can be better supported to have these conversations with their patients.

Exploring vaccination practices of midwives in British Columbia.

BACKGROUND: Registered midwives in British Columbia (BC) are primary health care practitioners for healthy people throughout pregnancy and for approximately 6 weeks postpartum. BC registered midwives are authorized to prescribe and administer certain vaccines to adults under their care during the perinatal period and hepatitis B vaccine to high-risk newborns. However, little has been documented about their recommendations for, and administration of, prenatal and infant vaccinations. This study surveyed midwives currently practicing in British Columbia to understand their vaccination practices. METHODS: An online survey was administered to the members of the Midwives Association of BC in spring 2018. Outcome measures were the proportion of midwives who discussed, recommended, and administered the following vaccines: influenza, varicella, rubella, and infant hepatitis B. The proportion of midwives who discussed and recommended infant vaccines was measured. Barriers to discussion, recommendation, and administration of vaccines were captured. RESULTS: Sixty-three percent of 108 respondents administered vaccines to their clients. Hepatitis B and rubella were the most frequent vaccines administered. Logistical concerns were the greatest barrier to vaccine administration. This was followed by the perception that vaccine administration is not within the scope of practice of midwives, especially for influenza vaccine. Midwives who administered vaccines were significantly more likely to discuss and recommend vaccines to their clients and their infants. CONCLUSIONS: The majority of BC midwives discuss, recommend, and administer vaccines to their clients. Our survey highlighted key areas to address to strengthen midwifery capacity to discuss, recommend, and provide prenatal and infant vaccines.

Listeriosis in infants: Prospective surveillance studies in Canada and Switzerland.

OBJECTIVES: International data on listeriosis during infancy from large populations are essential to guide evidence-based empiric antibiotic guidelines for sepsis in infancy. We aimed to determine the incidence, clinical manifestations, and outcome of listeriosis in infants <6 months of age in Canada and Switzerland. METHODS: Prospective, active surveillance of listeriosis in infants <6 months of age was conducted through the Canadian Paediatric Surveillance Program (May 2015 to April 2017) and the Swiss Paediatric Surveillance Unit (April 2017 to March 2018). Confirmed and probable cases were included. RESULTS: In Canada, eight sporadic listeriosis cases were reported (incidence, 1.1/100,000 live births/year). In Switzerland, four cases were reported (incidence, 4.5/100,000 live births/year) of which three were part of a confirmed outbreak with an unclear source. In the two countries, eight of the 12 cases (66.6%) presented as early-onset disease (within the first 7 days of life) and none presented after 28 days life. CONCLUSIONS: Neonatal listeriosis is rare. Infants presenting with sepsis, especially after 4 weeks of life, may not routinely require empiric antibiotic coverage for listeriosis. Outbreak-related cases still occur. Continued surveillance is important.

Immunogenicity of 2 and 3 Doses of the Quadrivalent Human Papillomavirus Vaccine up to 120 Months Postvaccination: Follow-up of a Randomized Clinical Trial.

BACKGROUND: Several countries have implemented a 2-dose (2D) human papillomavirus (HPV) vaccination schedule for adolescents based on immunobridging studies. We compared immunogenicity of 2D vs 3-dose (3D) schedules of the quadrivalent vaccine (4vHPV) up to 10 years after the first dose. METHODS: Girls aged 9-13 years were randomized to receive 2D or 3D and were compared with women aged 16-26 receiving 3D at day 1 and months 7, 24, and 120 after the first dose. Antibody levels for HPV6/11/16/18 were evaluated using the competitive Luminex immunoassay (cLIA) and total immunoglobulin G assay. Geometric mean titers (GMTs) and seropositivity rates were compared between the different groups at different time points. Noninferiority of GMT ratios was defined as the lower bound of the 2-sided 95% confidence interval (CI) being greater than 0.5. Kinetics of antibody titers over time among study groups were examined. RESULTS: At 120 months, data from 35 2D girls, 38 3D girls, and 30 3D women were used for analyses. cLIA seropositivity rates were above 95% for all HPV vaccine types and all schedules, except HPV18, with the lowest seropositivity observed among 3D women (60.0%; 95% CI, 40.6%-77.3%). GMT ratios (cLIA) for both 2D and 3D girls were noninferior to 3 doses in women for HPV6/11/16/18. Trends were comparable between assays. CONCLUSIONS: GMTs for HPV6/11/16/18 after 2D or 3D of 4vHPV in girls were noninferior to 3D in adult women up to 120 months postvaccination. This study demonstrates long-term immunogenicity of the 2D HPV vaccine schedule.

Randomized Trial of 2 Schedules of Meningococcal B Vaccine in Adolescents and Young Adults, Canada1.

Emergency vaccination programs often are needed to control outbreaks of meningococcal disease caused by Neisseria meningitidis serogroup B (MenB) on college campuses. Such campaigns expend multiple campus and public health resources. We conducted a randomized, controlled, multicenter, observer-blinded trial comparing immunogenicity and tolerability of an accelerated vaccine schedule of 0 and 21 days to a longer interval of 0 and 60 days for 4-component MenB vaccine (MenB-4C) in students 17-25 years of age. At day 21 after the first MenB-4C dose, we observed protective human serum bactericidal titers >4 to MenB strains 5/99, H44/76, and NZ 98/254 in 98%-100% of participants. Geometric mean titers increased >22-fold over baseline. At day 180, >95% of participants sustained protective titers regardless of their vaccine schedule. The most common adverse event was injection site pain. An accelerated MenB-4C immunization schedule could be considered for rapid control of campus outbreaks.

A Web Application About Herd Immunity Using Personalized Avatars: Development Study.

BACKGROUND: Herd immunity or community immunity refers to the reduced risk of infection among susceptible individuals in a population through the presence and proximity of immune individuals. Recent studies suggest that improving the understanding of community immunity may increase intentions to get vaccinated. OBJECTIVE: This study aims to design a web application about community immunity and optimize it based on users' cognitive and emotional responses. METHODS: Our multidisciplinary team developed a web application about community immunity to communicate epidemiological evidence in a personalized way. In our application, people build their own community by creating an avatar representing themselves and 8 other avatars representing people around them, for example, their family or coworkers. The application integrates these avatars in a 2-min visualization showing how different parameters (eg, vaccine coverage, and contact within communities) influence community immunity. We predefined communication goals, created prototype visualizations, and tested four iterative versions of our visualization in a university-based human-computer interaction laboratory and community-based settings (a cafeteria, two shopping malls, and a public library). Data included psychophysiological measures (eye tracking, galvanic skin response, facial emotion recognition, and electroencephalogram) to assess participants' cognitive and affective responses to the visualization and verbal feedback to assess their interpretations of the visualization's content and messaging. RESULTS: Among 110 participants across all four cycles, 68 (61.8%) were women and 38 (34.5%) were men (4/110, 3.6%; not reported), with a mean age of 38 (SD 17) years. More than half (65/110, 59.0%) of participants reported having a university-level education. Iterative changes across the cycles included adding the ability for users to create their own avatars, specific signals about who was represented by the different avatars, using color and movement to indicate protection or lack of protection from infectious disease, and changes to terminology to ensure clarity for people with varying educational backgrounds. Overall, we observed 3 generalizable findings. First, visualization does indeed appear to be a promising medium for conveying what community immunity is and how it works. Second, by involving multiple users in an iterative design process, it is possible to create a short and simple visualization that clearly conveys a complex topic. Finally, evaluating users' emotional responses during the design process, in addition to their cognitive responses, offers insights that help inform the final design of an intervention. CONCLUSIONS: Visualization with personalized avatars may help people understand their individual roles in population health. Our app showed promise as a method of communicating the relationship between individual behavior and community health. The next steps will include assessing the effects of the application on risk perception, knowledge, and vaccination intentions in a randomized controlled trial. This study offers a potential road map for designing health communication materials for complex topics such as community immunity.

Active surveillance of acute paediatric hospitalisations demonstrates the impact of vaccination programmes and informs vaccine policy in Canada and Australia.

Sentinel surveillance of acute hospitalisations in response to infectious disease emergencies such as the 2009 influenza A(H1N1)pdm09 pandemic is well described, but recognition of its potential to supplement routine public health surveillance and provide scalability for emergency responses has been limited. We summarise the achievements of two national paediatric hospital surveillance networks relevant to vaccine programmes and emerging infectious diseases in Canada (Canadian Immunization Monitoring Program Active; IMPACT from 1991) and Australia (Paediatric Active Enhanced Disease Surveillance; PAEDS from 2007) and discuss opportunities and challenges in applying their model to other contexts. Both networks were established to enhance capacity to measure vaccine preventable disease burden, vaccine programme impact, and safety, with their scope occasionally being increased with emerging infectious diseases' surveillance. Their active surveillance has increased data accuracy and utility for syndromic conditions (e.g. encephalitis), pathogen-specific diseases (e.g. pertussis, rotavirus, influenza), and adverse events following immunisation (e.g. febrile seizure), enabled correlation of biological specimens with clinical context and supported responses to emerging infections (e.g. pandemic influenza, parechovirus, COVID-19). The demonstrated long-term value of continuous, rather than incident-related, operation of these networks in strengthening routine surveillance, bridging research gaps, and providing scalable public health response, supports their applicability to other countries.

2017/18 and 2018/19 seasonal influenza vaccine safety surveillance, Canadian National Vaccine Safety (CANVAS) Network.

BackgroundThe Canadian National Vaccine Safety (CANVAS) network monitors the safety of seasonal influenza vaccines in Canada.AimTo provide enhanced surveillance for seasonal influenza and pandemic influenza vaccines.MethodsIn 2017/18 and 2018/19 influenza seasons, adults (≥ 15 years of age) and parents of children vaccinated with the seasonal influenza vaccine participated in an observational study using web-based active surveillance. Participants completed an online survey for health events occurring in the first 7 days after vaccination. Participants who received the influenza vaccine in the previous season, but had not yet been vaccinated for the current season, were unvaccinated controls.ResultsIn 2017/18, 43,751 participants and in 2018/19, 47,798 completed the online safety survey. In total, 957 of 30,173 participants vaccinated in 2017/18 (3.2%; 95% confidence interval (CI): 3.0-3.4) and 857 of 25,799 participants vaccinated in 2018/19 (3.3%; 95% CI: 3.1-3.5) reported a health problem of sufficient intensity to prevent their normal daily activities and/or cause them to seek medical care (including hospitalisation). This compared to 323 of 13,578 (2.4%; 95% CI: 2.1-2.6) and 544 of 21,999 (2.5%; 95% CI: 2.3-2.7) controls in each respective season. The event rate in vaccinated adults and children was higher than the background rate and was associated with specific influenza vaccines. The higher rate of events was associated with systemic symptoms and migraines/headaches.ConclusionIn 2017/18 and 2018/19, higher rates of events were reported following seasonal influenza vaccination than in the pre-vaccination period. This signal was associated with several seasonal influenza vaccine products.

Systematic review searches must be systematic, comprehensive, and transparent: a critique of Perman et al.

A high quality systematic review search has three core attributes; it is systematic, comprehensive, and transparent. The current over-emphasis on the primacy of systematic reviews over other forms of literature review in health research, however, runs the risk of encouraging publication of reviews whose searches do not meet these three criteria under the guise of being systematic reviews. This correspondence comes in response to Perman S, Turner S, Ramsay AIG, Baim-Lance A, Utley M, Fulop NJ. School-based vaccination programmes: a systematic review of the evidence on organization and delivery in high income countries. 2017; BMC Public Health 17:252, which we assert did not meet these three important quality criteria for systematic reviews, thereby leading to potentially unreliable conclusions. Our aims herein are to emphasize the importance of maintaining a high degree of rigour in the conduct and publication of systematic reviews that may be used by clinicians and policy-makers to guide or alter practice or policy, and to highlight and discuss key evidence omitted in the published review in order to contextualize the findings for readers. By consulting a research librarian, we identified limitations in the search terms, the number and type of databases, and the screening methods used by Perman et al. Using a revised Ovid MEDLINE search strategy, we identified an additional 1016 records in that source alone, and highlighted relevant literature on the organization and delivery of school-based immunization program that was omitted as a result. We argue that a number of the literature gaps noted by Perman et al. may well be addressed by existing literature found through a more systematic and comprehensive search and screening strategy. We commend both the journal and the authors, however, for their transparency in supplying information about the search strategy and providing open access to peer reviewer and editor's comments, which enabled us to understand the reasons for the limitations of that review.

Vaccination Against Influenza in Pregnancy: A Survey of Canadian Maternity Care Providers.

OBJECTIVE: Influenza vaccine uptake among Canadian pregnant individuals is suboptimal. Failure to incorporate vaccination into routine prenatal care and a lack of recommendations from healthcare providers are recognized as barriers to vaccination. The aim of this study was to assess Canadian maternity care providers' knowledge, attitudes, and practices regarding influenza vaccination in pregnancy. METHODS: A cross-sectional Web-based questionnaire was sent during July and August 2017 to family physicians, obstetricians-gynaecologists, midwives, pharmacists, and nurses who care for pregnant individuals. A multivariable logistic regression model was used to determine variables independently associated with providers' recommendation of the influenza vaccine in pregnancy. RESULTS: The analysis included 1061 providers. Most participants (85%) reported being vaccinated against influenza themselves, and 72% reported recommending the influenza vaccine to all of their pregnant patients during the previous influenza season. Participants' attitudes regarding influenza vaccination during pregnancy were generally positive: 64% strongly agreed that pregnant individuals are at an increased risk of complications from influenza, and 69% strongly agreed that it is safe to vaccinate pregnant individuals against influenza. The main determinants of participants' recommendations for influenza vaccination to all pregnant patients were following official recommendations on influenza vaccination, discussing vaccines with most or all pregnant individuals seen in their practice, and being vaccinated themselves during the previous influenza season. CONCLUSION: Enhancing influenza vaccine uptake in pregnancy is largely dependent on maternity care providers' recommendations. This study provides valuable insight on providers' knowledge, attitudes, and practices.

Neurodevelopmental outcome of HIV-exposed but uninfected infants in the Mother and Infants Health Study, Cape Town, South Africa.

OBJECTIVES: To compare neurodevelopmental outcomes of HIV-exposed uninfected (HEU) and HIV-unexposed uninfected (HUU) infants in a peri-urban South African population. HEU infants living in Africa face unique biological and environmental risks, but uncertainty remains regarding their neurodevelopmental outcome. This is partly due to lack of well-matched HUU comparison groups needed to adjust for confounding factors. METHODS: This was a prospective cohort study of infants enrolled at birth from a low-risk midwife obstetric facility. At 12 months of age, HEU and HUU infant growth and neurodevelopmental outcomes were compared. Growth was evaluated as WHO weight-for-age, length-for-age, weight-for-length and head-circumference-for-age Z-scores. Neurodevelopmental outcomes were evaluated using the Bayley scales of Infant Development III (BSID) and Alarm Distress Baby Scale (ADBB). RESULTS: Fifty-eight HEU and 38 HUU infants were evaluated at 11-14 months of age. Performance on the BSID did not differ in any of the domains between HEU and HUU infants. The cognitive, language and motor scores were within the average range (US standardised norms). Seven (12%) HEU and 1 (2.6%) HUU infant showed social withdrawal on the ADBB (P = 0.10), while 15 (26%) HEU and 4 (11%) HUU infants showed decreased vocalisation (P = 0.06). There were no growth differences. Three HEU and one HUU infant had minor neurological signs, while eight HEU and two HUU infants had macrocephaly. CONCLUSIONS: Although findings on the early neurodevelopmental outcome of HEU infants are reassuring, minor differences in vocalisation and on neurological examination indicate a need for reassessment at a later age.