Impacts of a mass vaccination campaign against pandemic H1N1 2009 influenza in Taiwan: a time-series regression analysis

Preventing and controlling intra-hospital spread of COVID-19 in Taiwan - Looking back and moving forward

COVID-19 has exposed major weaknesses in the healthcare settings. The surge in COVID-19 cases increases the demands of health care, endangers vulnerable patients, and threats occupational safety. In contrast to a hospital outbreak of SARS leading to a whole hospital quarantined, at least 54 hospital outbreaks following a COVID-19 surge in the community were controlled by strengthened infection prevention and control measures for preventing transmission from community to hospitals as well as within hospitals. Access control measures include establishing triage, epidemic clinics, and outdoor quarantine stations. Visitor access restriction is applied to inpatients to limit the number of visitors. Health monitoring and surveillance is applied to healthcare personnel, including self-reporting travel declaration, temperature, predefined symptoms, and test results. Isolation of the confirmed cases during the contagious period and quarantine of the close contacts during the incubation period are critical for containment. The target populations and frequency of SARS-CoV-2 PCR and rapid antigen testing depend on the level of transmission. Case investigation and contact tracing should be comprehensive to identify the close contacts to prevent further transmission. These facility-based infection prevention and control strategies help reduce hospital transmission of SARS-CoV-2 to a minimum in Taiwan.

Impact of prior infection and repeated vaccination on post-vaccination antibody titers of the influenza A(H1N1)pdm09 strain in Taiwan schoolchildren: Implications for public health

BACKGROUND

The objective of this study was to evaluate the effects of prior-infection and repeated vaccination on post-vaccination antibody titers.

METHODS

A(H1N1)pdm09 strain was included in 2009 pandemic monovalent, 2010-2011, and 2011-2012 trivalent influenza vaccines (MIVpdm09, TIV10/11, TIV11/12) in Taiwan. During the 2011-2012 influenza season, we conducted a prospective sero-epidemiological cohort study among schoolchildren from grades 1 - 6 in the two elementary schools in Taipei with documented A(H1N1)pdm09 vaccination records since 2009. Serum samples were collected at pre-vaccination, 1-month, and 4-months post-vaccination (T1, T2, T3). Anti-A(H1N1)pdm09 hemagglutination inhibition titers (HI-Ab-titers) were examined. We also investigated the impact of four vaccination histories [(1) no previous vaccination (None), (2) vaccinated in 2009-2010 season (09v), (3) vaccinated in 2010-2011 season (10v), and (4) vaccinated consecutively in 2009-2010 and 2010-2011 seasons (09v + 10v)] and pre-vaccination HI-Ab levels on post-vaccination HI-Ab responses as well as adjusted vaccine effectiveness (aVE) against serologically-defined infection from T2 to T3.

RESULTS

TIV11/12 had zero serious adverse events reported. A(H1N1)pdm09 strain in TIV11/12 elicited seroprotective Ab-titers in 98% of children and showed promising protection (aVE: 70.3% [95% confidence interval (CI): 51.0-82.1%]). Previously unvaccinated but infected children had a 3.96 times higher T2 geometric mean titer (T2-GMT) of HI-Ab than those naïve to A(H1N1)pdm09 (GMT [95% CI]: 1039.7[585.3-1845.9] vs. 262.5[65.9-1045], p = 0.046). Previously vaccinated children with seroprotective T1-Ab-titers had a higher T2-GMT and a greater aVE than those with non-seroprotective T1-Ab-titers. Repeatedly vaccinated children had lower T2-GMT than those receiving primary doses of TIV11/12. However, after controlling prior infection and T1-Ab-titers, differences in T2-GMT among the four vaccination histories became insignificant (p = 0.16).

CONCLUSION

This study supports the implementation of annual mass-vaccination with A(H1N1)pdm09 in schoolchildren for three consecutive influenza seasons when vaccine and circulating strains were well matched, and found that prior infection and pre-vaccination HI-Ab levels positively impacted post-vaccination HI-Ab responses.

Taiwan's Response to Influenza: A Seroepidemiological Evaluation of Policies and Implications for Pandemic Preparedness

OBJECTIVES

To evaluate class suspension and mass vaccination implemented among Taipei schoolchildren during the 2009 influenza pandemic and investigate factors affecting antibody responses.

METHODS

We conducted 2 cohort studies on: (1) 972 schoolchildren from November 2009-March 2010 to evaluate pandemic policies and (2) 935 schoolchildren from November 2011-March 2012 to verify factors in antibody waning. Anti-influenza H1N1pdm09 hemagglutination inhibition antibodies (HI-Ab) were measured from serum samples collected before vaccination, and at 1 and 4 months after vaccination. Factors affecting HI-Ab responses were investigated through logistic regression and generalized estimating equation.

RESULTS

Seroprevalence of H1N1pdm09 before vaccination was significantly higher among schoolchildren who experienced class suspensions than those who did not (59.6% vs 47.5%, p<0.05). Participating in after-school activities (adjusted odds ratio [aOR]=2.47, p=0.047) and having ≥3 hours per week of exercise (aOR=2.86, p=0.019) were significantly correlated with H1N1pdm09 infection. Two doses of the H1N1pdm09 vaccine demonstrated significantly better antibody persistence than 1 dose (HI-Ab geometric mean titer: 132.5 vs 88.6, p=0.047). Vaccine effectiveness after controlling for preexisting immunity was 86% (32%-97%). Exercise ≥3 hours per week and preexisting immunity were significantly associated with antibody waning/maintenance.

CONCLUSIONS

This study is the first to show that exercise and preexisting immunity may affect antibody waning. Further investigation is needed to identify immune correlates of protection.

Prospective health surveillance for COVID-19 among health care workers at a university medical center in Taiwan, January to June 2020

Background

Healthcare personnel (HCP) at the front line of care are exposed to occupational hazards that place them at risk for infection, which then endanger patient safety and compromise the capability of the healthcare workforce. As of March 8, 2021 more than 420,170 HCP in US had been infected with SARS CoV-2 with 1388 deaths. In two Taiwan hospitals COVID-19 outbreaks involved HCP and resulted in shutdown of service. This report describes our prospective health surveillance of the HCP and COVID-19 containment measures in a teaching hospital in Taiwan during Jan. 1 through June 30, 2020.

Methods

We prospectively monitored incidents, defined as an HCP with the predefined symptoms, reported by HCP through the web-based system. HCP were managed based on an algorithm that included SARS CoV-2 RNA PCR testing. Infection prevention and control policy/practice were reviewed.

Results

This hospital took care of 17 confirmed COVID-19 cases during the study period and the first Case was admitted on January 23, 2020. Among the 14,210 HCP, there were 367 incident events. Of 283 HCP tested for SARS CoV-2, 179 had predefined symptoms. These included 10 HCP who met the national case definition for COVID-19 infection and 169 based on Extended COVID-19 Community Screening program. The other 104 asymptomatic HCP were tested based on hospital policy. All of them had tested negative.

Conclusion

We attribute our success in preventing COVID-19 infections among HCP to rapid, proactive, decisive, integrated national and institutional response in the early stages of the epidemic

Global dynamics of a novel deterministic and stochastic SIR epidemic model with vertical transmission and media coverage

In this paper, we study a novel deterministic and stochastic SIR epidemic model with vertical transmission and media coverage. For the deterministic model, we give the basic reproduction number R 0 which determines the extinction or prevalence of the disease. In addition, for the stochastic model, we prove existence and uniqueness of the positive solution, and extinction and persistence in mean. Furthermore, we give numerical simulations to verify our results.

Tailoring time series models for forecasting coronavirus spread: Case studies of 187 countries

When will the coronavirus end? Are the current precautionary measures effective? To answer these questions it is important to forecast regularly and accurately the spread of COVID-19 infections. Different time series forecasting models have been applied in the literature to tackle the pandemic situation. The current research efforts developed few of these models and validates its accuracy for selected countries. It becomes difficult to draw an objective comparison between the performance of these models at a global scale. This is because, the time series trend for the infection differs between the countries depending on the strategies adopted by the healthcare organizations to decrease the spread. Consequently, it is important to develop a tailored model for a country that allows healthcare organizations to better judge the effect of the undertaken precautionary measures, and provision more efficiently the needed resources to face this disease. This paper addresses this void. We develop and compare the performance of the time series models in the literature in terms of root mean squared error and mean absolute percentage error.

Optimizing influenza vaccine policies for controlling 2009-like pandemics and regular outbreaks

Background

This study examined the effectiveness of various vaccine policies against influenza. The transmission rate was calculated by use of the time-series influenza-like illness case during the year of 2009 and recent epidemics in Taiwan.

Methods

We developed a stochastic compartmental model to analyze the transmission of influenza, where the population was stratified by location and age group, and the vaccine distribution was considered using the current policy. The simulation study compared the previous vaccine policy and a new policy with expanded coverage and various lengths of the vaccination campaign. The sensitivity analysis investigated different levels of vaccine efficacy to confirm the robustness of the recommended policies.

Results

Doubling vaccine coverage can decrease the number of infections effectively in the regular epidemic scenario. However, a peak of infections occurs if the duration of implementing vaccination is too long. In the 2009-like pandemic scenario, both increasing vaccine doses and reducing the program’s duration can mitigate infections, although the early outbreak restricts the effectiveness of vaccination programs.

Conclusions

The finding indicates that only increasing vaccine coverage can reduce influenza infections. To avoid the peak of infections, it is also necessary to execute the vaccination activity immediately. Vaccine efficacy significantly impacts the vaccination policy’s performance. When vaccine efficacy is low, neither increasing vaccination doses nor reducing vaccination timeframe prevents infections. Therefore, the variation in vaccine efficacy should be taken into account when making immunization policies against influenza.

A method for evaluating and comparing immunisation schedules that cover multiple diseases: Illustrative application to the UK routine childhood vaccine schedule

BACKGROUND

In the UK, the childhood immunisation programme is given in the first 5 years of life and protects against 12 vaccine-preventable diseases. Recently, this programme has undergone changes with addition of vaccination against Meningitis B from September 2015 and the removal of the primary dose of protection against Meningitis C from July 2016. These hanges have direct impact on the associated diseases but in addition may induce indirect effects on the vaccines that are given simultaneously or later in the programme. In this work, we developed a novel formal method to evaluate the impact of vaccination changes to one aspect of the programme across an entire vaccine programme.

METHODS

Firstly, we combined transmission modelling (for four diseases) and historic data synthesis (for eight diseases) to project, for each disease, the disease burden at different levels of effective coverage against the associated disease. Secondly, we used a simulation model to determine the vector of effective coverage against each disease under three variations of the current childhood schedule. Combining these, we calculated the vector of disease burden across the programme under different scenarios, and assessed the direct and indirect effects of the schedule changes.

RESULTS

Through illustrative application of our novel framework to three scenarios of the current childhood immunisation programme in the UK, we demonstrated the feasibility of this unifying approach. For each disease in the programme, we successfully quantified the residual disease burden due to the change. For some diseases, the change was indirectly beneficial and reduced the burden, whereas for others the effect was adverse and the change increased the disease burden.

CONCLUSIONS

Our results demonstrate the potential benefit of considering the programme-wide impact of changes to an immunisation schedule, and our framework is an important step in the development of a means for systematically doing so.

Centennial review of influenza in Taiwan

The history of influenza in Taiwan can be traced up to the 1918 H1N1 Spanish flu pandemic, followed by several others including the 1957 H2N2, 1968 H3N2, and the 2009 new H1N1. A couple of avian influenza viruses of H5N1 and H7N9 also posed threats to the general public in Taiwan in the two recent decades. Nevertheless, two seasonal influenza A viruses and two lineages of influenza B viruses continue causing annual endemics one after the other, or appearing simultaneously. Their interplay provided interesting evolutionary trajectories for these viruses, allowing us to computationally model their global migrations together with the data collected elsewhere from different geographical locations. An island-wide laboratory-based surveillance network was also established since 2000 for systematically collecting and managing the disease and molecular epidemiology. Experiences learned from this network helped in encountering and managing newly emerging infectious diseases, including the 2003 SARS and 2009 H1N1 outbreaks.

Psychogenic illness following vaccination: exploratory study of mass vaccination against pandemic influenza A (H1N1) in 2009 in South Korea

Purpose

Adverse events during mass vaccination campaigns have had a profoundly negative impact on vaccine coverage rates. The objective of the study was to identify the characteristics of reported psychogenic illness cases following mass vaccination that needed further interventions of the national immunization program.

Materials and Methods

We collected documents that were submitted to the Korea Centers for Disease Control and Prevention for vaccine injury compensation, and analyzed cases of psychogenic illness following pandemic influenza A (H1N1) vaccination in 2009 which were confirmed by the Korean Advisory Committee on Vaccine Injury Compensation.

Results

During the 2009-2010 influenza season, 13 million Koreans were vaccinated against pandemic influenza. Of 28 reported psychogenic illness cases following immunization, 25 were vaccinated through school-located mass immunization. Significant numbers of them were female adolescents (68%) or had underlying vulnerable conditions or emotional life stressors (36%). They required lengthy hospitalization (median, 7 days) and high medical costs (median, US $1,582 per case).

Conclusion

Health authorities and organizers of future mass vaccinations should be well aware of the possible occurrence of psychogenic illness, acknowledge their detailed characteristics, and take its economic burden into account to mitigate the risk of transmission of infectious diseases efficiently.

Mass Vaccinations at the United States Naval Academy

We analyzed the mass influenza vaccination clinic process at the United States Naval Academy to identify gaps and implement changes for improvement. The Lean Six Sigma methodology was employed. Total number of staff members working the clinic and total hours worked were measured at baseline in August 2013 and after implementation in August 2014 to determine improvement. The clinic was moved from a hallway to an auditorium, and a linear patient flow was established. Staff members wore vests for easy identification, and the supply box was reorganized. Training was standardized and given to all staff members before working in the clinic. These changes decreased the number of staff members required to work in the clinic from 62 to 40 (-35.5%) and decreased the total number of hours worked from 558 to 360 (-35.5%). The changes successfully improved the mass vaccination clinic by decreasing staffing and hours required. These changes can be adopted in other settings to increase community capacity and readiness.

Predictive Symptoms and Signs of Laboratory-confirmed Influenza: A Prospective Surveillance Study of Two Metropolitan Areas in Taiwan

Influenza infection poses annual threats and leads to significant morbidity and mortality. Early diagnosis is the key to successful treatment. Laboratory-based diagnosis has various limitations. Diagnosis based on symptoms or signs is still indispensable in clinical practice. We investigated the symptoms or signs associated with laboratory-confirmed influenza.A prospective study across 2 influenza seasons was performed from June 2010 to June 2012 at 2 branches (Taipei and Lin-Kou) of Chang Gung Memorial Hospital. Patients who visited outpatient clinics with suspected acute respiratory tract infection were sampled by throat swab or nasopharyngeal swab. RT-PCR and/or virus culture were used as a reference standard. We used logistic regression to identify the symptoms or signs associated with laboratory-confirmed influenza infection. We also evaluated the performance metrics of different influenza-like illness used in Taiwan, the USA, and WHO.A total of 158 patients were included in the study. The prevalence of influenza infection was 45% (71/158). Fever, cough, rhinorrhea, sneezing, and nasal congestion were significant predictors for influenza infection. Whereas fever + cough had a best sensitivity (86%; confidence interval [CI] 76%-93%), fever + cough and sneezing had a best specificity (77%; CI 62%-88%). Different case definitions of influenza-like illness had comparable accuracy in sensitivity and specificity.Clinical diagnosis based on symptoms and signs is useful for allocating resources, identifying those who may benefit from early antiviral therapy and providing valuable information for surveillance purpose.