Multiple Regression Analysis of the Number of users of Nurseries for Children with Mild Illness and Trends in Common Infectious Diseases before and during the COVID-19 Pandemic in Hiroshima, Japan

DOI: https://doi.org/10.21203/rs.3.rs-789437/v1

Abstract

Background: Most Japanese daycare centers do not accept ill children, even if they only have minor symptoms. Nurseries for children with mild illness have been developed (mostly in urban areas), but use of these nurseries dropped sharply during the COVID-19 pandemic. There are two possible reasons for this decrease: efforts to prevent COVID-19 infection reduced common infectious diseases in children and eliminated the need for these nurseries, or parents refrained from using these nurseries because they feared a COVID-19 outbreak. This study aimed to clarify the reason for the decreased use of these nurseries.

Methods: Data on trends in common infectious diseases reported by sentinel medical facilities to public health centers in Hiroshima Prefecture, Japan from January 2018 to March 2021 were provided by the Hiroshima CDC (Center for Disease Control and Prevention). The number of monthly users of nurseries for children with mild illness in the 23 municipalities in Hiroshima Prefecture over the same period was obtained by a questionnaire survey. Multiple regression analysis was used to assess the association between the numbers of nursery users and common infectious diseases before and during the COVID-19 pandemic.

Results: The regression coefficient between the number of users of these nurseries and number of common infectious diseases did not change between before and during the COVID-19 pandemic, except for an increase in intercept during the pandemic.

Conclusions: The decreased number of children with mild illnesses using nurseries during the COVID-19 pandemic was related to the decrease in common infectious diseases, and not to parents refraining from using nurseries because they feared a COVID-19 outbreak. Many parents may still have wished to use nurseries for children with mild illness during the COVID-19 pandemic.

Introduction

Infants and toddlers often suffer from acute illnesses (e.g., infectious diseases) and visit medical institutions twice a month on average [1]. However, general daycare centers in Japan do not accept unwell children, even those with mild symptoms, to prevent infectious disease outbreaks [2]. Therefore, nurseries for children with mild illness have been developed, although most of these are in urban areas [3, 4].

During the COVID-19 pandemic, the number of users of nurseries for children with mild illness dropped sharply. A survey conducted by the National Council for Childcare for Sick Children showed the number of nursery users was 15% in May 2020 compared with the same period in the previous year [5]. Many nurseries for children with mild illness are operated by private medical institutions, and some may be in financial crisis because of this decreased use.

Two possible causes for the decline in use of nurseries for children with mild illness during the COVID-19 pandemic have been proposed. First, efforts to prevent COVID-19 infection (e.g., wearing masks, washing hands more frequently) may have reduced the number of common infectious diseases in children [6]. In addition, if parents worked from home during the COVID-19 pandemic, their children may also have remained at home and had less chance of getting infected. Second, parents may have refrained from using nurseries for children with mild illness as well as out-of-hours pediatric clinics [7] because they feared a COVID-19 outbreak. The reduced use of nurseries for children with mild illness may be considered desirable if it was due to a reduction in children with common infectious diseases. Conversely, if parents could not use these nurseries because they feared a COVID-19 outbreak, the child-rearing support function was deteriorated, which is undesirable. However, it is unclear which of these reasons caused the drop in use of nurseries for children with mild illness.

If the decline in nursery use was due to the decreased number of common infectious diseases during the COVID-19 pandemic, the regression coefficient between the number of nursery users and the number of common infectious diseases would be the same before and during the pandemic (Fig. 1A). However, if the use of these nurseries was reduced because of fear of a COVID-19 outbreak, the regression coefficient would be lower during the pandemic compared with the pre-pandemic period (Fig. 1B). To clarify why the number of users of nurseries for children with mild illness decreased during the COVID-19 pandemic, this study analyzed the relationship between the number of nursery users and the number of common infectious diseases before and during the COVID-19 pandemic.

Material And Methods

The target area for this study was Hiroshima Prefecture, one of Japan’s 47 prefectures, which has a population of about 2.8 million people [8]. The prefecture has seven public health centers that conduct weekly surveys of common infectious diseases (Fig. 2). The trends of these infectious diseases are reported to the public health centers by the four types of sentinel medical facilities (pediatric, influenza, ophthalmology, designated sentinel medical facilities; Table 1). Data on the weekly trends in common infectious diseases from January 2018 to March 2021 were provided by the Hiroshima CDC (Center for Disease Control and Prevention). As in the Hiroshima CDC Monthly Report [6], the weekly incidence of these diseases was converted to a monthly incidence by adding to results for 4–5 weeks.

Data on the number of monthly users of nurseries for children with mild illness from January 2018 to March 2021 in the 23 municipalities in Hiroshima Prefecture were obtained using a questionnaire survey. The survey form was distributed to the municipalities on April 2, 2021. The survey was resent to cities and towns that did not respond on May 6, 2021, and June 1, 2021. Collected data on the number of children using nurseries for children with mild illnesses were categorized and tabulated for each of the seven health center areas.

The Day Care Center Infectious Disease Management Guidelines (2018 Revised) [2], specify matters related to resuming daycare attendance after contracting a common infectious disease (Table 1). These guidelines indicate that most general daycare centers may not accept children with these common infectious diseases. Therefore, it is expected that there would be a strong correlation between the number of the infectious diseases listed in these guidelines and the number of users of nurseries for children with mild illness. Multiple regression analysis was performed to test the relationship between the number of users of these nurseries and the number of sentinel-reported diseases in the seven public health center areas. A dummy variable was used to represent before and during the COVID-19 pandemic.

Because of the small number of reports from designated sentinel medical facilities, this study analyzed the number of infectious diseases reported by three types of sentinel medical facilities (pediatric, influenza, and ophthalmology sentinel-reported diseases; Table 1). Pediatric sentinel medical facilities are intended for patients under age 15 years, whereas influenza and ophthalmology sentinel medical facilities are intended for adults and children. Therefore, in the multiple regression analysis with the number of users of nurseries for children with mild illness as the dependent variable, the total numbers of pediatric, influenza, and ophthalmology sentinel-reported diseases were set as separate independent variables. The pandemic dummy variable was set as 0 before March 1, 2020, and 1 thereafter, because most schools in Japan were temporarily closed to prevent COVID-19 as of March 2, 2020 [9]. Under the above conditions, the following multiple regression equation was established.

y = a1 * x1 + a2 * x2 + a3 * x3 + a4 * x4

+ (a5 * x1 * x4) + (a6 * x2 * x4) + (a7 * x3 *x4) + b

It can also be expressed as:

y = (a1 + a5 * x4) * x1 + (a2 + a6 * x4) * x2 + (a3 + a7 * x4) * x3

+ (a4 * x4 + b)

The number of monthly users of nurseries for children with mild illness was indicated by y, and the regression coefficients by a1–a7 and b. The numbers of monthly cases of pediatric, influenza, and ophthalmology sentinel-reported diseases were indicated by x1–x3, respectively, and the pandemic dummy variable (0 before March 1, 2020, and 1 thereafter) was indicated by x4.

In addition, multiple regression analysis was performed to test the relationship between the number of users of nurseries for children with mild illness and the number of each sentinel-reported disease. All statistical analyses were performed using SPSS version 23.0.0.3 (IBM Corp., Armonk), P-values less than 0.05 were considered statistically significant.

Results

The questionnaire survey collected data on the number of users of nurseries for children with mild illness for 39 months (January 2018 to March 2021) from all 23 municipalities in Hiroshima Prefecture (recovery rate 100%). The 23 municipalities were divided into the seven health center areas, and the data for users of these nurseries in 273 (39 * 7) month-areas were included in this study (Fig. 2).

Figure 3 shows the monthly numbers of pediatric, influenza, and ophthalmology sentinel-reported diseases throughout Hiroshima Prefecture. Influenza epidemics are usually seen from the end of the year to the beginning of the following year but were not evident from the end of 2020 to the beginning of 2021. Figure 4 shows scatter plots between the number of users of nurseries for children with mild illness and the monthly numbers of pediatric sentinel-reported diseases and influenza. Table 2 shows the results of the multiple regression analysis between the number of monthly users of nurseries for children with mild illness and the monthly numbers of pediatric, influenza, and ophthalmology sentinel-reported diseases. The adjusted coefficient of determination by multiple regression analysis was 0.791. The regression coefficients for the number of pediatric sentinel-reported diseases and influenza were significantly above 0 (P < 0.001), but this was not the case for ophthalmology sentinel-reported diseases (P = 0.347). The coefficient for the pandemic dummy variable (0 before March 1, 2020, and 1 thereafter) was also significantly above 0 (P < 0.001). However, the product of the pandemic dummy variable multiplied by the numbers of pediatric, influenza, and ophthalmology sentinel-reported diseases did not have coefficients significantly different from 0 (P = 0.243, 0.728, and 0626, respectively).

Table 3 shows the results of the multiple regression analysis between the number of monthly users of nurseries for children with mild illness and the number of each sentinel-reported disease. The adjusted coefficient of determination by multiple regression analysis was 0.849. All sentinel-reported diseases had coefficients significantly above 0, except for pharyngoconjunctival fever, herpangina, mumps, and acute hemorrhagic conjunctivitis.

Discussion

The present analysis of the use of nurseries for children with mild illness in Hiroshima Prefecture confirmed that the number of nursery users dropped sharply during the COVID-19 pandemic. However, no significant interaction was observed between the number of reported cases of common infectious diseases and the pandemic dummy variable in the multivariate regression analysis. The regression coefficients for the number of nursery users and the number of common infectious diseases during the COVID-19 pandemic were unchanged from before the pandemic (Fig. 1A), except for an increase in the intercept (a4 * x4 + b; Table 2) during the pandemic. It is therefore likely that the use of nurseries for children with mild illness may have decreased during the COVID-19 pandemic because the number of common infectious diseases decreased, rather than because parents refrained from using nurseries for these children. With a few exceptions, the number of each type of infectious disease was also positively associated with the number of users of nurseries for children with mild illness.

During the COVID-19 pandemic, the proportion and absolute number of patients with mild illnesses who visited after-hours clinics in Hiroshima, Japan decreased [7]. However, coverage of vaccinations against common infectious diseases did not change significantly between before and during the pandemic [10]. Similarly, the demand for daycare for children with mild illness may not have changed significantly between before and during the pandemic. The reasons for this are unknown. However, it has been reported that the telecommuting rate outside the three major metropolitan areas in Japan (Tokyo, Kinki, and Chukyo) during the pandemic was only 12% [11]. Therefore, the childcare support environment for children with mild illness in Hiroshima Prefecture may not have changed significantly between before and during the pandemic.

I found a significant positive correlation between the pandemic dummy variable (0 before March 1, 2020, and 1 thereafter) and the number of users of nurseries for children with mild illness. The intercept of the regression line was larger during the COVID-19 pandemic than before the pandemic. The reason for this finding is unknown. Before the pandemic, these nurseries may have not accepted more children with mild illnesses than their capacity because of the large number of applicants who wanted to use them. However, during the pandemic, the small number of users suggests that most children up to the capacity could have used these nurseries. This may have led to an increase in the intercept of the regression equation. Although the central government requested that prefectures considered reducing the provisional capacity for childcare to prevent outbreaks of COVID-19 on April 7, 2020 [12], the decrease in nursery users appeared to have been greater than this reduction [5]. Therefore, it is probable that most children were able to use these nurseries during the pandemic.

Most nurseries for children with mild illness are not profitable despite being privately owned [13]. Therefore, a decrease in the number of nursery users may lead to these facilities ceasing to operate. Children often suffer from acute illnesses such as infectious diseases [1], meaning that they cannot attend a general daycare center. A survey conducted by the National Diet Library of Japan [14] found no data on daycare services for children with minor illnesses in other countries as it is standard practice to provide care at home for children when they become ill. However, many parents in Japan do not take paid leave when their children are acutely ill because of peer pressure not to burden their colleagues by taking leave [15, 16]. Improving Japan’s work culture is an important step, but this will take time. Therefore, it is necessary to create a child-rearing support environment that can be used by both healthy children and those with mild illnesses. To create such an environment, it will be necessary to invest more public funds.

Limitations

1) The severity of reported cases of infectious diseases was unknown. In addition, it was also unknown how many days these nurseries were used after such illness.

2) The age distribution of each sentinel-reported disease was unknown, and therefore may or may not have matched the age range for childcare.

3) The employment status of parents and the availability of alternative caregivers (e.g., family members and friends) were unknown.

However, about 80% of the number of users of nurseries for children with mild illness can be explained by the number of reported cases of infectious diseases (adjusted coefficient of determination about 0.8). Therefore, it is likely that most of these nursery users can be explained by the number of sentinel-reporting diseases.

Conclusions

The decrease in the number of children with mild illness using nurseries during the COVID-19 pandemic may be related to the decrease in common infectious diseases, rather than to parents refraining from using nurseries because they feared a COVID-19 outbreak. Many parents may have wished to continue to use nurseries for children with a mild illness even during the COVID-19 pandemic.

Abbreviations

AHC: acute hemorrhagic conjunctivitis; AIG, infectious gastroenteritis; COVID-19: coronavirus disease 2019; EB, exanthem subitum; EI: erythema infectiosum; EKC, epidemic keratoconjunctivitis; EYE: ophthalmology sentinel-reported diseases; FLU: influenza; GAS: group A streptococcal pharyngitis; HA: herpangina; HFM: hand, foot, and mouth disease; Hiroshima CDC: Hiroshima Center for Disease Control and Prevention; PCF: pharyngoconjunctival fever; PED: pediatric sentinel-reported diseases; RS: respiratory syncytial virus infection; VZV: chickenpox.

Declarations

Ethics approval

As a result of discussions with the Medical Research Ethics Committee for Hiroshima International University, it was determined that this study did not require ethical review (approval number: Rin 20-036, March 22, 2021; Rin 21-020, July 21, 2021). 

Consent to participate

Not applicable. 

Consent for publication

Not applicable. 

Availability of data

All data analyzed during this study are included in this article and its supplementary information file. 

Competing interests

The author declares that there are no competing interests. 

Funding

This work was supported by MEXT Promotion of Distinctive Joint Research Center Program (Grant Number JPMXP0619217850). 

Author contributions

AE designed this study, analyzed the data, and wrote the manuscript.  

Acknowledgements

The author thanks Audrey Holmes, MA, from Edanz (https://jp.edanz.com/ac) for editing a draft of the manuscript.  

Author information

Akira Ehara, Department of Health Services Management, Hiroshima International University, Higashihiroshima City, Hiroshima, Japan

References

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Tables

Due to technical limitations, tables are only available as a download in the Supplemental Files section.