Considering economic analyses in the revision of the preventive vaccination law: A new direction for health policy-making in Japan?

Reply to Volkman et al. Comment on "Fust et al. The Potential Economic Impact of the Updated COVID-19 mRNA Fall 2023 Vaccines in Japan. Vaccines 2024, 12, 434"

In their comment [...].

The Burden of Preventable Adverse Drug Events on Hospital Stay and Healthcare Costs in Japanese Pediatric Inpatients: The JADE Study

Background:

Adverse drug events (ADEs) are a burden to the healthcare system. Preventable ADEs, which was ADEs due to medication errors, could be reduced if medication errors can be prevent or ameliorate.

Objective:

We investigated the burden of preventable ADEs on the length of hospital stay (LOS) and costs, and estimated the national burden of preventable ADEs in pediatric inpatients in Japan.

Methods:

We analyzed data from the Japan Adverse Drug Events (JADE) study on pediatric patients and estimated the incidence of preventable ADEs and associated extended LOS. Costs attributable to extended LOS by preventable ADEs were calculated using a national statistics database and we calculated the effect of preventable ADEs on national cost excess.

Results:

We included 907 patients with 7377 patient-days. Among them, 31 patients (3.4%) experienced preventable ADEs during hospitalization. Preventable ADEs significantly increased the LOS by 14.1 days, adjusting for gender, age, ward, resident physician, surgery during hospitalization, cancer, and severe malformation at birth. The individual cost due to the extended LOS of 14.1 days was estimated as USD 8258. We calculated the annual extra expense for preventable ADEs in Japan as USD 329 676 760. Sensitivity analyses, considering the incidence of preventable ADEs and the length of hospital stay, showed that the expected range of annual extra expense for preventable ADEs in Japan is between USD 141 468 968 and 588 450 708.

Conclusion:

Preventable ADEs caused longer hospitalization and considerable extra healthcare costs in pediatric inpatients. Our results would encourage further efforts to prevent and ameliorate preventable ADEs.

Modelling the optimal target age group for seasonal influenza vaccination in Japan

BACKGROUND

In Japan, the current influenza vaccination programme is targeting older individuals. On the other hand, epidemics of influenza are likely to be mainly driven by children. In this study, we consider the most cost-effective target age group for a seasonal influenza vaccination programme in Japan.

METHODS

We constructed a deterministic compartmental Susceptible-Exposed-Infectious-Recovered (SEIR) model with data from the 2012/13 to 2014/15 influenza seasons in Japan. Bayesian inference with Markov Chain Monte Carlo method was used for parameter estimation. Cost-effectiveness analyses were conducted from public health care payer's perspective.

RESULTS

A scenario targeting children under 15 was expected to reduce the number of cases 6,382,345 compared to the current strategy. A scenario targeting elderly population (age over 49 years) was expected to reduce the number of cases 693,206. The children targeted scenario demonstrated negative ICER (incremental cost-effectiveness ratio) value. On the other hand, elderly targeted scenario demonstrated higher ICER value than the willingness to pay (50,000 USD/QALY).

CONCLUSIONS

A vaccination programme which targets children under 15 is predicted to have much larger epidemiological impact than those targeting elderly.

Interdependency in vaccination policies among Japanese municipalities

Economic theory predicts that vaccination policies at the local level can be negatively affected by the policies of neighboring regions because of free-riding motives, whereas positive dependency may exist due to policy diffusions among localities. By using the unique variations in the provision of vaccination subsidies in Japan, we assess how vaccination policies in a local government are affected by the decisions of neighboring governments. We find that the provision of vaccination subsidies is positively correlated with the decisions of neighboring localities. Moreover, a correlation is found with neighboring municipalities within the same prefecture but not with those in surrounding prefectures, indicating that the correlations are likely to arise because of mimicking behavior among localities within a prefecture. Our results show that vaccination policies tend to be formed following neighboring municipalities and do not necessarily aim to optimize community health, thus questioning the autonomy of local government authorities regarding vaccination policies.

Vaccines for post-exposure prophylaxis against varicella (chickenpox) in children and adults

BACKGROUND

The prevention of varicella (chickenpox) using live attenuated varicella vaccines has been demonstrated both in randomised controlled trials (RCTs) and in population-based immunisation programmes in countries such as the United States and Australia. Many countries do not routinely immunise children against varicella and exposures continue to occur. Although the disease is often mild, complications such as secondary bacterial infection, pneumonitis and encephalitis occur in about 1% of cases, usually leading to hospitalisation. The use of varicella vaccine in persons who have recently been exposed to the varicella zoster virus has been studied as a form of post-exposure prophylaxis (PEP).

OBJECTIVES

To assess the efficacy and safety of vaccines for use as PEP for the prevention of varicella in children and adults.

SEARCH METHODS

We searched CENTRAL (2014, Issue 1), MEDLINE (1966 to March week 1, 2014), EMBASE (January 1990 to March 2014) and LILACS (1982 to March 2014). We searched for unpublished trials registered on the clinicaltrials.gov and WHO ICTRP websites.

SELECTION CRITERIA

RCTs and quasi-RCTs of varicella vaccine for PEP compared with placebo or no intervention. The outcome measures were efficacy in prevention of clinical cases and/or laboratory-confirmed clinical cases and adverse events following vaccination.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted and analysed data using Review Manager software.

MAIN RESULTS

We identified three trials involving 110 healthy children who were siblings of household contacts. The included trials varied in study quality, vaccine used, length of follow-up and outcomes measured and, as such, were not suitable for meta-analysis. We identified high or unclear risk of bias in two of the three included studies. Overall, 13 out of 56 vaccine recipients (23%) developed varicella compared with 42 out of 54 placebo (or no vaccine) recipients (78%). Of the vaccine recipients who developed varicella, the majority only had mild disease (with fewer than 50 skin lesions). In the three trials, most participants received PEP within three days following exposure; too few participants were vaccinated four to five days post-exposure to ascertain the efficacy of vaccine given more than three days after exposure. No included trial reported on adverse events following immunisation.

AUTHORS' CONCLUSIONS

These small trials suggest varicella vaccine administered within three days to children following household contact with a varicella case reduces infection rates and severity of cases. We identified no RCTs for adolescents or adults. Safety was not adequately addressed.