The temporal trend of influenza-associated morbidity and the impact of early appearance of antigenic drifted strains in a Southeast Asian country

Association between Otosclerosis and Rubella in Taiwan: A Nationwide Case-Control Study

Otosclerosis is an early adult-onset disease that is associated with 5-9% and 18-22% of all cases of hearing and conductive hearing loss, respectively, and it is suspected to have a viral etiology. However, the role of viral infection in otosclerosis is still inconclusive. This study aimed to investigate whether rubella infection was associated with otosclerosis risk. We conducted a nationwide case-control study in Taiwan. Data were retrospectively analyzed from the Taiwan National health Insurance Research Database. Cases consisted of all patients who were aged ≥6 years and had a first-time diagnosis of otosclerosis for the period between 2001 and 2012. The controls were exact matched to cases in a 4:1 ratio by birth year, sex, and must survive in the index year of their matched cases. Adjusted odds ratio (OR) and 95% confidence interval (CI) were estimated by using conditional logistic regression. We examined 647 otosclerosis cases and 2588 controls without otosclerosis. Among the 647 patients with otosclerosis, 241 (37.2%) were male and 406 (62.8%) were female, with most aged between 40 and 59 years, with a mean age of 44.9 years. After adjusting for age and sex, conditional logistic regression revealed that exposure to rubella was not associated with a significant increase in otosclerosis risk (adjusted OR, 2.0; 95% CI, 0.18-22.06, p = 0.57). In conclusion, this study did not show that rubella infection was associated with the risk of otosclerosis in Taiwan.

Association Between the Use of Antibiotics, Antivirals, and Hospitalizations Among Patients With Laboratory-confirmed Influenza

BACKGROUND

Clinicians may prescribe antibiotics to influenza patients at high risk for bacterial complications. We explored the association between antibiotics, antivirals, and hospitalization among people with influenza.

METHODS

A retrospective cohort study of patients with confirmed influenza with encounters during January 2011-January 2019 was conducted using data from the Veterans Affairs Informatics and Computing Infrastructure (VINCI). We compared inpatient hospitalizations (all-cause and respiratory) within 30 days of influenza diagnosis between 4 patient cohorts: (1) no treatment (n = 4228); (2) antibiotic only (n = 671); (3) antiviral only (n = 6492); and (4) antibiotic plus antiviral (n = 1415). We estimated relative risk for hospitalization using Poisson generalized linear model and robust standard errors.

RESULTS

Among 12 806 influenza cases, most were white men (mean age, 57-60 years). Those with antivirals only, antibiotic plus antiviral, and antibiotics only all had a statistically significant lower risk of all-cause and respiratory hospitalization compared to those without treatment. Comparing the antibiotic plus antiviral cohort to those who were prescribed an antiviral alone, there was a 47% lower risk for respiratory hospitalization (relative risk, 0.53 [95% confidence interval, .31-.94]), and no other statistical differences were detected.

CONCLUSIONS

Those prescribed an antiviral, antibiotic, or both had a lower risk of hospitalization within 30 days compared to those without therapy. Furthermore, intervention with both an antibiotic and antiviral had a lower risk of respiratory hospitalization within 30 days compared to those with an antiviral alone. Importantly, the absolute magnitude of decreased risk with antibiotic plus antiviral therapy is small and must be interpreted within the context of the overall risk of antibiotic usage.

A Population-Based Propensity Score-Matched Study to Assess the Impact of Repeated Vaccination on Vaccine Effectiveness for Influenza-Associated Hospitalization Among the Elderly

Background

Influenza is a major cause of morbidity and mortality in the elderly worldwide. Influenza vaccination can prevent morbidity/mortality from influenza infection. A gap of 1–2 years, before an epidemic strain is recommended by the World Health Organization (WHO) to be the vaccine strain in Southeast Asia, has been reported; this results in a high rate of vaccine mismatch and excess influenza-associated morbidity. The aim of the current study was to evaluate the effect of repeated vaccination on vaccine effectiveness (VE) among the elderly in Taiwan, during years with and without early appearance of antigenically drifted strains.

Methods

A historical cohort study was conducted to evaluate the impact of repeated vaccination on the reduction of influenza-associated hospitalization among persons older than 64 years over two influenza seasons: 2007–08, with all circulating virus strains mismatched, and 2008–09, with all virus strains matched with the vaccine strains, considering four exposure effects, namely current vaccine effect, sequential vaccination effect, residual protection effect and no vaccination effect. Propensity score matching on vaccination status was performed to ensure similar baseline characteristics between the groups that received and did not receive vaccination.

Results

Only current-year vaccination in combination with prior history of annual revaccination significantly reduced the risk of hospitalization, with adjusted hazard ratios of 0.68 (95% CI: 0.54, 0.85) and 0.74 (95% CI: 0.57, 0.95) during the 2007–08 and 2008–09 influenza seasons, respectively. Further stratification showed that even during the 2007–08 influenza season, when all vaccinations were mismatched with the circulating strains, sequential vaccinations still significantly reduced influenza-associated hospitalization in the female population aged 68–74 and 75–84 years, with adjusted VE of 25.2% (95% CI: −9.6, 49.0%) and 36.9% (95% CI: 17.1, 52.0%), respectively.

Conclusion

Our study supports the recommendation of annual revaccination against influenza in the elderly, even though the circulating strain of influenza virus was antigenically mismatched with the vaccine strains.

A Matched Influenza Vaccine Strain Was Effective in Reducing the Risk of Acute Myocardial Infarction in Elderly Persons: A Population-Based Study

The aim of this study was to explore whether matched or mismatched strains of influenza vaccines (IVs) are beneficial at reducing the risk of acute myocardial infarction (AMI) in elderly persons.Data were obtained from the Longitudinal Health Database 2005 (LHID 2005) which is maintained by the National Health Insurance Research Institute in Taiwan. The analytical data included individuals who were vaccinated with mismatched vaccines during the October 2007 to December 2007 season and individuals vaccinated with matched strains during the October 2008 to December 2008 season. All participants were 65 years of age and older. In this analysis, individuals were considered to be exposed if their records showed that they were vaccinated against influenza, and they were considered to be nonexposed if they were not vaccinated during these seasons. A Cox hazard model was used to estimate AMI hazard ratio.This study enrolled 93,051 exposed and 109,007 unexposed individuals. The AMI hazards ratios (HRs) for the men and women exposed to mismatched vaccine (in 2007) were 0.990 (95% confidence interval [CI], 0.745-1.316) and 1.102 (95% CI: 0.803-1.513), respectively. Men exposed to matched vaccines (in 2008) had significant HRs (HR: 0.681; 95% CI: 0.509-0.912) while the HRs in the women were barely significant (HR: 0.737; 95% CI: 0.527-1.029).AMI risk could be particularly reduced in men if the IV matches well with the circulating strains in elderly people 65 years of age and older.

Recording of Influenza-Like Illness in UK Primary Care 1995-2013: Cohort Study

BACKGROUND

There is a lack of recent studies examining recording of influenza-like illness (ILI) in primary care in the UK over time and according to population characteristics. Our aim was to determine time trends and socio-demographic patterns of ILI recorded consultations in primary care.

METHODS

We used The Health Improvement Network (THIN) UK primary care database and extracted data on all ILI consultations between 1995 and 2013. We estimated ILI recorded consultation rates per 100,000 person-weeks (pw) by age, gender, deprivation and winter season. Negative binomial regression models were used to examine time trends and the effect of socio-demographic characteristics. Trends in ILI recorded consultations were compared to trends in consultations with less specific symptoms (cough or fever) recorded.

RESULTS

The study involved 7,682,908 individuals in 542 general practices. The ILI consultation rate decreased from 32.5/100,000 pw (95% confidence interval (CI) 32.1, 32.9) in 1995-98 to 15.5/100,000 pw (95% CI 15.4, 15.7) by 2010-13. The decrease occurred prior to 2002/3, and rates have remained largely stable since then. Declines were evident in all age groups. In comparison, cough or fever consultation rates increased from 169.4/100,000 pw (95% CI 168.6, 170.3) in 1995-98 to 237.7/100,000 pw (95% CI 237.2, 238.2) in 2010-13. ILI consultation rates were highest among individuals aged 15-44 years, higher in women than men, and in individuals from deprived areas.

CONCLUSION

There is substantial variation in ILI recorded consultations over time and by population socio-demographic characteristics, most likely reflecting changing recording behaviour by GPs. These results highlight the difficulties in using coded information from electronic primary care records to measure the severity of influenza epidemics across time and assess the relative burden of ILI in different population subgroups.