Influenza-like illness in Norway: clinical course, attitudes towards vaccination and preventive measures during the 2009 pandemic

The Norwegian PraksisNett: a nationwide practice-based research network with a novel IT infrastructure

PURPOSE

Clinical research in primary care is relatively scarce. Practice-based research networks (PBRNs) are research infrastructures to overcome hurdles associated with conducting studies in primary care. In Norway, almost all 5.4 million inhabitants have access to a general practitioner (GP) through a patient-list system. This gives opportunity for a PBRN with reliable information about the general population. The aim of the current paper is to describe the establishment, organization and function of PraksisNett (the Norwegian Primary Care Research Network).

MATERIALS AND METHODS

We describe the development, funding and logistics of PraksisNett as a nationwide PBRN.

RESULTS

PraksisNett received funding from the Research Council of Norway for an establishment period of five years (2018-2022). It is comprised of two parts; a human infrastructure (employees, including academic GPs) organized as four regional nodes and a coordinating node and an IT infrastructure comprised by the Snow system in conjunction with the Medrave M4 system. The core of the infrastructure is the 92 general practices that are contractually linked to PraksisNett. These include 492 GPs, serving almost 520,000 patients. Practices were recruited during 2019-2020 and comprise a representative mix of rural and urban settings spread throughout all regions of Norway.

CONCLUSION

Norway has established a nationwide PBRN to reduce hurdles for conducting clinical studies in primary care. Improved infrastructure for clinical studies in primary care is expected to increase the attractiveness for studies on the management of disorders and diseases in primary care and facilitate international research collaboration. This will benefit both patients, GPs and society in terms of improved quality of care.Key pointsPractice-based research networks (PBRNs) are research infrastructures to overcome hurdles associated with conducting studies in primary careImproved infrastructure for clinical studies in primary care is expected to increase the attractiveness for studies on the management of disorders and diseases in primary care and facilitate international research collaborationWe describe PraksisNett, a Norwegian PBRN consisting of 92 general practices including 492 GPs, serving almost 520,000 patientsAn advanced and secure IT infrastructure connects the general practices to PraksisNett and makes it possible to identify and recruit patients in a novel way, as well as reuse clinical dataPraksisNett will benefit both patients, GPs and society in terms of improved quality of careThis paper may inform and inspire initiatives to establish PBRNs elsewhere.

Does C-reactive protein predict time to recovery and benefit from oseltamivir treatment in primary care patients with influenza-like illness? A randomized controlled trial secondary analysis

OBJECTIVE

Recovery time and treatment effect of oseltamivir in influenza-like illness (ILI) differs between patient groups. A point-of-care test to better predict ILI duration and identify patients who are most likely to benefit from oseltamivir treatment would aid prescribing decisions in primary care. This study aimed to investigate whether a C-reactive protein (CRP) concentration of ≥30 mg/L can predict (1) ILI disease duration, and (2) which patients are most likely to benefit from oseltamivir treatment.

DESIGN

Secondary analysis of randomized controlled trial data.

SETTING

Primary care in Lithuania, Sweden and Norway during three consecutive influenza seasons 2016-2018.

SUBJECTS

A total of 277 ILI patients aged one year or older and symptom duration of ≤72 h.

MAIN OUTCOME MEASURES

Capillary blood CRP concentration at baseline, and ILI recovery time defined as having 'returned to usual daily activity' with residual symptoms minimally interfering.

RESULTS

At baseline, 20% (55/277) had CRP concentrations ≥30mg/L (range 0-210). CRP concentration ≥30 mg/L was not associated with recovery time (adjusted hazards ratio (HR) 0.80: 95% CI 0.50-1.3; p = 0.33). Interaction analysis of CRP concentration ≥30 mg/L and oseltamivir treatment did not identify which patients benefit more from oseltamivir treatment (adjusted HR 0.69: 95% CI 0.37-1.3; p = 0.23).

CONCLUSION

There was no association between CRP concentration of ≥30 mg/L and recovery time from ILI. Furthermore, CRP could not predict which ILI patients benefit more from oseltamivir treatment. Hence, we do not recommend CRP testing for predicting ILI recovery time or identifying patients who will receive particular benefit from oseltamivir treatment.Key PointsPredicting disease course of influenza-like illness (ILI), and identifying which patients benefit from oseltamivir treatment is a challenge for physicians.• There was no association between CRP concentration at baseline and recovery time in patients consulting with ILI in primary care.• There was no association between CRP concentration at baseline and benefit from oseltamivir treatment.• We, therefore, do not recommend CRP testing for predicting recovery time or in decision-making concerning oseltamivir prescribing in ILI patients.

Compliance with preventative measures during the COVID-19 pandemic in the USA and Canada: Results from an online survey

This study explored people's compliance with recommended preventative measures during early stages of the COVID-19 pandemic. An online survey was administered in June 2020 in the USA and Canada (N = 1,405). Regression analysis found that when controlling for other factors, age and political ideology were significant predictors of compliance with preventative measures. A content analysis of narrative answers of compliance/noncompliance found that the majority of individuals intended to comply with preventative measures, with primary reasons as social responsibility, self-protection, and protection of family members. Reasons identified for not complying were viewing preventative practices as unnecessary, getting mixed messages from various sources about effectiveness, distrust in government and inability to comply. This study informs social workers on intervention strategies on micro, mezzo and macro levels of practice.

Antibody levels in a cohort of pregnant women after the 2009 influenza A(H1N1) pandemic: Waning and association with self-reported severity and duration of illness

BACKGROUND

A population-based pregnancy cohort was established in Norway to study potential effects of exposure to the 2009 influenza pandemic or pandemic vaccination during pregnancy.

OBJECTIVES

We studied maternal A(H1N1)pdm09-specific hemagglutination inhibition (HI)-titer levels and waning in women with influenza-like illness (ILI) in pregnancy compared to vaccinated women. Moreover, we studied the association between HI-titers and self-reported severity and duration of ILI.

METHODS

HI-titers against the pandemic virus were measured in maternal blood samples obtained at birth, 3-9 months after exposure, and linked with information about pregnancy, influenza and vaccination from national registries and a cohort questionnaire.

RESULTS

Among 1821 pregnant women included, 43.7% were unvaccinated and 19.3% of these had ILI. HI-titers were low (geometric mean titer (GMT) 11.3) in the unvaccinated women with ILI. Higher HI-titers (GMT 37.8) were measured in the vaccinated women. Estimated HI-titer waning was similar for vaccinated women and women with ILI. Most ILI episodes were moderate and lasted 3-5 days. Women with ILI reporting specific influenza symptoms such as fever or cough had higher HI-titers than women without these symptoms. Women who reported being "very ill" or illness duration of >5 days had higher HI-titers than women reporting less severe illness or illness of shorter duration, respectively.

CONCLUSIONS

Antibody waning was similar in vaccinated women and women with ILI. More severe ILI or longer duration of illness was associated with higher HI-titers. Most unvaccinated pregnant women with ILI had low HI-titers, probably due to moderate illness and HI-titer waning between exposure and sampling.

Pandemic influenza and subsequent risk of type 1 diabetes: a nationwide cohort study

AIMS/HYPOTHESIS

Case reports have linked influenza infections to the development of type 1 diabetes. We investigated whether pandemic and seasonal influenza infections were associated with subsequent increased risk of type 1 diabetes.

METHODS

In this population-based registry study, we linked individual-level data from national health registries for the entire Norwegian population under the age of 30 years for the years 2006-2014 (2.5 million individuals). Data were obtained from the National Registry (population data), the Norwegian Patient Registry (data on inpatient and outpatient specialist care), the Primary Care Database, the Norwegian Prescription Database and the Norwegian Surveillance System for Communicable Diseases. Pandemic influenza was defined as either a clinical influenza diagnosis during the main pandemic period or a laboratory-confirmed test. Seasonal influenza was defined by a clinical diagnosis of influenza between 2006 and 2014. We used Cox regression to estimate HRs for new-onset type 1 diabetes after an influenza infection, adjusted for year of birth, sex, place of birth and education.

RESULTS

The adjusted HR for type 1 diabetes after pandemic influenza infection was 1.19 (95% CI 0.97, 1.46). In the subgroup with laboratory-confirmed influenza A (H1N1), influenza was associated with a twofold higher risk of subsequent type 1 diabetes before age 30 years (adjusted HR: 2.26, 95% CI 1.51, 3.38).

CONCLUSIONS/INTERPRETATION

Overall, we could not demonstrate a clear association between clinically reported pandemic influenza infection and incident type 1 diabetes. However, we found a twofold excess of incident diabetes in the subgroup with laboratory-confirmed pandemic influenza A (H1N1).

Could information about herd immunity help us achieve herd immunity? Evidence from a population representative survey experiment

AIMS

Immunisation causes dramatic reductions in morbidity and mortality from infectious diseases; however, resistance to vaccination is nonetheless widespread. An understudied issue - explored here - is whether appeals to collective as opposed to individual benefits of vaccination encourage people to vaccinate. Knowledge of this is important not least with respect to the design of public health campaigns, which often lack information about the collective benefits of vaccination.

METHODS

Using a between-subjects experimental survey design, we test whether information about the effects of herd immunity influences people's decision to vaccinate. A representative sample of Norwegians was confronted with a hypothetical scenario in which a new and infectious disease is on its way to Norway. The sample was split in three - a control group and two treatment groups. The one treatment group was provided information about collective benefits of vaccination; the other was provided information about the individual benefits of vaccination.

RESULTS

Both treatments positively affect people's decision to vaccinate; however, informing about the collective benefits has an even stronger effect than informing about the individual benefits.

CONCLUSIONS

Our results suggest that people's decision about whether to vaccinate and thus contribute to herd immunity is influenced by concern for others. Thus, stressing the collective benefits of vaccination could increase the effectiveness of health campaigns.

Influenza and risk of later celiac disease: a cohort study of 2.6 million people

OBJECTIVES

Influenza has been linked to autoimmune conditions, but its relationship to subsequent celiac disease (CD) is unknown. Our primary aim was to determine the risk of CD after influenza. A secondary analysis examined the risk of CD following pandemic influenza vaccination.

METHODS

This nationwide register-based cohort study included 2,637,746 Norwegians (born between 1967-2013) followed during 2006-2014 with information on influenza diagnosed in primary or non-primary care, pandemic vaccination (Pandemrix), and subsequent CD. Cox regression yielded hazard ratios adjusted (HR) for socio-demographic characteristics and earlier healthcare use.

RESULTS

During 13,011,323 person-years of follow-up 7321 individuals were diagnosed with CD (56/100,000 person-years). There were 351,666 individuals diagnosed with influenza, including 82,980 during the 2009-2010 pandemic, and 969,968 individuals were vaccinated. Compared with participants without influenza, who had a CD incidence of 55/100,000 person-years, those diagnosed with seasonal and pandemic influenza had a rate of 68 and 78, per 100,000 person-years, respectively. The HR for CD was 1.29 (95%CI, 1.21-1.38) after seasonal influenza and 1.29 (95%CI, 1.15-1.44) after pandemic influenza; HRs remained significantly increased one year after exposure, when restricted to laboratory-confirmed influenza, and after multivariate adjustments. The reverse association, i.e., risk of influenza after CD, was not significant (HR 1.05; 95%CI, 0.98-1.12). The HR for CD after pandemic vaccination was 1.08 (95%CI, 1.03-1.14).

CONCLUSION

A positive association with influenza diagnosis is consistent with the hypothesis that infections may play a role in CD development. We could neither confirm a causal association with pandemic vaccination, nor refute entirely a small excess risk.

A systematic review of factors affecting intended and actual adherence with antiviral medication as treatment or prophylaxis in seasonal and pandemic flu

The aim of this review was to identify factors predicting actual or intended adherence to antivirals as treatment or prophylaxis for influenza. Literature from inception to March 2015 was systematically reviewed to find studies reporting predictors of adherence to antivirals and self‐reported reasons for non‐adherence to antivirals. Twenty‐six studies were included in the review; twenty identified through the literature search and six through other means. Of these studies, 18 assessed predictors of actual adherence to antivirals, whereas eight assessed predictors of intended adherence. The most commonly found predictor of, and self‐reported reason for, non‐adherence was the occurrence of side effects. Other predictors include perceptions surrounding self‐efficacy, response efficacy and perceived personal consequences as well as social influences of others' experiences of taking antivirals. Predictors identified in this review can be used to help inform communications to increase adherence to antivirals in both seasonal and pandemic influenza.

The swine flu vaccine, public attitudes, and researcher interpretations: a systematic review of qualitative research

BACKGROUND

During pandemics, health authorities may be uncertain about the spread and severity of the disease and the effectiveness and safety of available interventions. This was the case during the swine flu (H1N1) pandemic of 2009-2010, and governments were forced to make decisions despite these uncertainties. While many countries chose to implement wide scale vaccination programmes, few accomplished their vaccination goals. Many research studies aiming to explore barriers and facilitators to vaccine uptake have been conducted in the aftermath of the pandemic, including several qualitative studies.

AIMS

1. To explore public attitudes to the swine flu vaccine in different countries through a review of qualitative primary studies. 2. To describe and discuss the implications drawn by the primary study authors.

METHODS

Systematic review of qualitative research studies, using a broadly comparative cross case-study approach. Study quality was appraised using an adaptation of the Critical Appraisal Skills Programme (CASP) quality assessment tool.

RESULTS

The review indicates that the public had varying opinions about disease risk and prevalence and had concerns about vaccine safety. Most primary study authors concluded that participants were uninformed, and that more information about the disease and the vaccine would have led to an increase in vaccine uptake. We find these conclusions problematic. We suggest instead that people's questions and concerns were legitimate given the uncertainties of the situation at the time and the fact that the authorities did not have the necessary information to convince the public. Our quality assessment of the included studies points to a lack of reflexivity and a lack of information about study context. We suggest that these study weaknesses are tied to primary study authors' lack of acknowledgement of the uncertainties surrounding the disease and the vaccine.

CONCLUSION

While primary study authors suggest that authorities could increase vaccine uptake through increased information, we suggest instead that health authorities should be more transparent in their information and decision-making processes in future pandemic situations.

Influenza in workplaces: transmission, workers' adherence to sick leave advice and European sick leave recommendations

Background: Knowledge about influenza transmission in the workplace and whether staying home from work when experiencing influenza-like illness can reduce the spread of influenza is crucial for the design of efficient public health initiatives. Aim: This review synthesizes current literature on sickness presenteeism and influenza transmission in the workplace and provides an overview of sick leave recommendations in Europe for influenza. Methods: A search was performed on Medline, Embase, PsychINFO, Cinahl, Web of Science, Scopus and SweMed to identify studies related to workplace contacts, -transmission, -interventions and compliance with recommendations to take sick leave. A web-based survey on national recommendations and policies for sick leave during influenza was issued to 31 European countries. Results: Twenty-two articles (9 surveys; 13 modelling articles) were eligible for this review. Results from social mixing studies suggest that 20–25% of weekly contacts are made in the workplace, while modelling studies suggest that on average 16% (range 9–33%) of influenza transmission occurs in the workplace. The effectiveness of interventions to reduce workplace presenteeism is largely unknown. Finally, estimates from studies reporting expected compliance with sick leave recommendations ranged from 71 to 95%. Overall, 18 countries participated in the survey of which nine (50%) had issued recommendations encouraging sick employees to stay at home during the 2009 A(H1N1) pandemic, while only one country had official recommendations for seasonal influenza. Conclusions: During the 2009 A(H1N1) pandemic, many European countries recommended ill employees to take sick leave. Further research is warranted to quantify the effect of reduced presenteeism during influenza illness.

Characteristics of patients and physicians correlated with regular influenza vaccination in patients treated for type 2 diabetes: a follow-up study from 2008 to 2011 in southeastern France

We studied a cohort of 110 823 patients treated with oral hypoglycaemic agents for type 2 diabetes in southeastern France from 1 January 2008 to 31 December 2011, to identify influenza vaccination coverage trends and the patient and physician correlates of influenza vaccine (IFV) uptake. We used French national health insurance fund (NHIF) databases to identify these patients and collect data on their IFV reimbursement claims (IFVC) and patient and physician characteristics. We used multilevel multivariate polytomous logistic regressions to test the correlates of IFVC. Between 2008 and 2011 the annual IFVC rate varied from 33.7% to 32.3% in the 18-64 age group and from 69.5% to 61.1% in the 65 + age group, among whom we saw a clear trend towards reduced vaccination after 2008. In the younger group, the probability of regular vaccination each year from 2008 to 2011 increased with diabetes severity and duration, comorbidities, and the number of general practitioner and nurse visits; it was higher among patients seeing endocrinologists and lower among low-income patients than in other patients. In the older group, there was no association with either diabetes severity or physician specialty. These results suggest different patterns of correlates of influenza vaccination according to age. Endocrinologists might help to improve IFV uptake in the younger group of patients with type 2 diabetes. Communication strategies regarding influenza vaccination should be adapted to age, and collaboration between healthcare professionals should be reinforced to achieve vaccination objectives for these patients.

Intentions to perform non-pharmaceutical protective behaviors during influenza outbreaks in Sweden: a cross-sectional study following a mass vaccination campaign

Failure to incorporate the beliefs and attitudes of the public into theoretical models of preparedness has been identified as a weakness in strategies to mitigate infectious disease outbreaks. We administered a cross-sectional telephone survey to a representative sample (n = 443) of the Swedish adult population to examine whether self-reported intentions to improve personal hygiene and increase social distancing during influenza outbreaks could be explained by trust in official information, self-reported health (SF-8), sociodemographic factors, and determinants postulated in protection motivation theory, namely threat appraisal and coping appraisal. The interviewees were asked to make their appraisals for two scenarios: a) an influenza with low case fatality and mild lifestyle impact; b) severe influenza with high case fatality and serious disturbances of societal functions. Every second respondent (50.0%) reported high trust in official information about influenza. The proportion that reported intentions to take deliberate actions to improve personal hygiene during outbreaks ranged between 45–85%, while less than 25% said that they intended to increase social distancing. Multiple logistic regression models with coping appraisal as the explanatory factor most frequently contributing to the explanation of the variance in intentions showed strong discriminatory performance for staying home while not ill (mild outbreaks: Area under the curve [AUC] 0.85 (95% confidence interval 0.82;0.89), severe outbreaks AUC 0.82 (95% CI 0.77;0.85)) and acceptable performance with regard to avoiding public transportation (AUC 0.78 (0.74;0.82), AUC 0.77 (0.72;0.82)), using handwash products (AUC 0.70 (0.65;0.75), AUC 0.76 (0.71;0.80)), and frequently washing hands (AUC 0.71 (0.66;0.76), AUC 0.75 (0.71;0.80)). We conclude that coping appraisal was the explanatory factor most frequently included in statistical models explaining self-reported intentions to carry out non-pharmaceutical health actions in the Swedish outlined context, and that variations in threat appraisal played a smaller role in these models despite scientific uncertainties surrounding a recent mass vaccination campaign.

Capacity and adaptations of general practice during an influenza pandemic

Background

GPs play a major role in influenza epidemics, and most patients with influenza-like-illness (ILI) are treated in general practice or by primary care doctors on duty in out-of-hours services (OOH). Little is known about the surge capacity in primary care services during an influenza pandemic, and how the relationship between them changes.

Aim

To investigate how general practice and OOH services were used by patients during the 2009 pandemic in Norway and the impact of the pandemic on primary care services in comparison to a normal influenza season.

Materials

Data from electronic remuneration claims from all OOH doctors and regular GPs for 2009.

Methods

We conducted a registry-based study of all ILI consultations in the 2009 pandemic with the 2008/09 influenza season (normal season) as baseline for comparison.

Results

The majority (82.2%) of ILI consultations during the 2009 pandemic took place in general practice. The corresponding number in the 2008/09 season was 89.3%. Compared with general practice, the adjusted odds ratio for ILI with all other diagnoses as reference in OOH services was 1.23 (95% CI, 1.18, 1.27) for the 2008/2009 season and 1.87 (95% CI, 1.84, 1.91) for the pandemic influenza season. In total there was a 3.3-fold increase in ILI consultations during the pandemic compared to the 2008/09 season. A 5.5-fold increase of ILI consultations were observed in OOH services in comparison to the 2008/09 season. Children and young adults with ILI were the most frequent users of OOH services during influenza periods.

Conclusions

The autumn pandemic wave resulted in a significantly increased demand on primary care services. However, GPs in primary care services in Norway showed the ability to increase capacity in a situation with increased patient demand.

Pandemic 2009 H1N1 influenza among health care workers

To evaluate factors associated with pandemic influenza among health care workers (HCWs), a case-case-control study was conducted with 52 confirmed cases, 120 influenza-negative cases, and 102 controls. Comorbidities (odds ratio [OR], 19.05; 95% confidence interval [95% CI]: 4.75-76.41), male sex (OR, 5.11; 95% CI: 1.80-14.46), and being a physician (OR, 8.58; 95% CI: 2.52-29.27) were independent risk factors for pandemic influenza infection among HCWs. Contact with symptomatic coworker or social contact was protective (OR, 0.11; 95% CI: 0.04-0.29). To our knowledge, this is the first study of factors associated with acquiring influenza involving HCW in nonsevere cases.

Prevention of influenza among travellers attending at a UK travel clinic: beliefs and perceptions. A cross-sectional study

BACKGROUND

Travellers' compliance with measures to prevent influenza through the use of antivirals and influenza vaccine remains very poor despite influenza being one of the commonest travel and vaccine-preventable diseases. A study was undertaken to assess travellers' beliefs, perceptions and intentions to take antivirals for the treatment and prevention of influenza during the H1N1 pandemic.

METHODS

A cross-sectional survey (n = 96) of travellers who attended the Royal Free Travel Health Centre, London, UK was undertaken in September 2009. A self-administered questionnaire was completed by a traveller in advance of their pre-travel health consultation. Logistic regression identified variables independently associated with compliance.

RESULTS

Influenza vaccination uptake for the 5 years preceding the study was found to be 20·8%. This was statistically significantly higher for older travellers and those with underlying health conditions (P < 0·005). Mean intention to comply with antiviral drugs on a preventive and therapeutic basis was 58% and 72%, respectively, and this varied markedly with age and with dispensed antimalarial chemoprophylaxis.

CONCLUSION

This study identifies some beliefs and perceptions travellers consider with regard to the therapeutic and preventive influenza use of antivirals during the H1N1 pandemic; it underscores the importance of travellers receiving hemisphere appropriate influenza vaccination. The external validity of these study findings requires further corroboration involving other travel clinics and different cohorts of travellers during seasonal activity or outbreaks of influenza. These findings could guide the development of future strategies for the prevention of influenza in travellers.