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. 2023 Mar 19:13623613231160631. doi: 10.1177/13623613231160631

Prevalence and severity of COVID-19 among children and adolescents with autism spectrum disorders in the Republic of Korea

Jieun Yun 1,*, Beomjun Kang 2,*, Jae-ryun Lee 3, Hyejin Lee 2,3,†,✉, Jin Yong Lee 2,4,5,†
PMCID: PMC10030889  PMID: 36935608

Abstract

Autism spectrum disorder is considered a vulnerability for many diseases including coronavirus disease 2019. This study investigated trends in coronavirus disease 2019 among children and adolescents with and without autism spectrum disorder and to evaluate whether there are differences in the prevalence, severity, and case fatality rate. We used data from the National Health Insurance Service for all people ⩽19 years of age. Among 9,187,211 children and adolescents ⩽19 years of age, 402,499 (4.4%) were coronavirus disease 2019–positive. Of the total population, 63,054 (0.7%) were diagnosed with autism spectrum disorder, among whom 2557 (4.1%) were coronavirus disease 2019–positive. The coronavirus disease 2019 prevalence was lower among children and adolescents with autism spectrum disorder, with 4055 per 100,000 versus 4383 per 100,000 without autism spectrum disorder (p < 0.001). However, children and adolescents with autism spectrum disorder exhibited a higher proportion of hospitalization (24.8% vs 21.5%) and severe disease (0.2% vs 0.01%) than those without autism spectrum disorder (p < 0.001); the length of hospital stay among inpatients was not different between the two groups (9.5 vs 9.4 days, respectively; p = 0.48). There were six deaths in total, with no deaths among children and adolescents with autism spectrum disorder. The quarantine policies have played a great role in sustaining low prevalence and higher hospitalization rates among children and adolescents with autism spectrum disorder.

Lay abstract

It is more difficult to prevent coronavirus disease 2019 in children and adolescents with autism spectrum disorder, as they have trouble communicating and adjusting to their new daily lives like wearing masks and social distancing. However, there have not been many studies that focused on coronavirus disease 2019 among children and adolescents with autism spectrum disorder. We included all Korean citizens under the age of 19 as our study subjects. Among them, we found out the prevalence, severity, and case fatality of coronavirus disease 2019 in children and adolescents with and without autism spectrum disorder. The prevalence of coronavirus disease 2019 among children and adolescents with autism spectrum disorder was lower than that of those without autism spectrum disorder. For severity, children and adolescents with autism spectrum disorder were more likely to enter severe stages of disease and had higher hospitalization rates than those without autism spectrum disorder. There were no deaths among children and adolescents with autism spectrum disorder, while a few died among children and adolescents without autism spectrum disorder. However, due to the small number of deaths, it was difficult to determine whether there was a link between autism spectrum disorder and coronavirus disease 2019 deaths. We found that the appropriate quarantine policies have played a great role in sustaining overall low prevalence and higher hospitalization rates among children and adolescents with autism spectrum disorder than those without autism spectrum disorder. Furthermore, because Korea has fewer schools and facilities (i.e. personal care, social training, and skilled nursing facility) for children and adolescents with autism spectrum disorder than other countries, those with autism spectrum disorder have fewer social contacts than even before the COVID-19 pandemic.

Keywords: autism spectrum disorder, case fatality, COVID-19, prevalence, severity

Since the start of the coronavirus disease 2019 (COVID-19) pandemic, many people have been infected and have died worldwide (WHO Coronavirus Disease (COVID-19) Dashboard, 2022). However, the threats posed by pandemics do not apply equally to everyone (Centers for Disease Control and Prevention. Pneumonia, 2021; Centers for Disease Control and Prevention. TB and Children, 2021; Hernandez-Vargas et al., 2014; Nwachuku & Gerba, 2006; Poehling et al., 2006; Thompson et al., 2004). Previous studies have reported that COVID-19-related health outcomes, including incidence of COVID-19, severity, and mortality rates, are worse in socioeconomically disadvantaged groups (Lee et al., 2021). Socioeconomic level, race, old age, and disability are known factors that influence health outcomes (Singh & Jemal, 2017; Webb Hooper et al., 2020; Wiemken et al., 2020). In particular, individuals with disabilities are well-known vulnerable groups (Choi et al., 2021; Vai et al., 2021). Among these, individuals with autism spectrum disorders (ASDs) are reported to be vulnerable to infectious diseases such as COVID-19. To prevent the acquisition of infectious diseases, changes in the activities of daily living, such as wearing masks and social distancing, are necessary. However, it is difficult for individuals with ASD to adapt to these changes compared to those without ASD (Bitan et al., 2022). Therefore, it is believed that children and adolescents with ASD are more vulnerable to COVID-19; however, few studies have been conducted.

In Korea, there are approximately 470,000 births annually, and 0.5%–0.7% of them have ASD, diagnosed by a doctor at age 8 when they enter elementary school. Epidemiological studies have reported an ASD prevalence of up to 2.7%, but the risk of COVID-19 in children and adolescents with ASD is not yet studied (Yoo et al., 2022).

As such, the present study aimed to determine the prevalence, severity, and case fatality rate associated with COVID-19 among children and adolescents ⩽19 years of age and to evaluate whether there are differences between children and adolescents with and without ASD. We investigated whether health inequalities exist by examining differences in COVID-19-related health outcomes between children and adolescents with and without ASD.

Methods

Study design and population

This retrospective cross-sectional study used claims data provided by the National Health Insurance Service (NHIS). In Korea, it is compulsory to join the NHIS, and 97% of citizens are NHIS beneficiaries. The remaining 3%, who are unable to pay insurance premiums, are Medical Aid recipients and are supported by the government budget for medical expenses (2018 Medical Aid Statistics, 2019). As the sole insurer in Korea, the NHIS houses data regarding diagnosis, treatment, and prescriptions covered by insurance. This study was conducted on all populations ⩽19 years of age as of March 31, 2022. Data on COVID-19 prevalence, severity, hospitalization, and case fatality for study participants were used from 1 January 2020, when the first case of COVID-19 was detected in Korea, to 31 March 2022, when a massive spread of the Omicron variant occurred.

The total population was based on data from the Korean National Statistical Office. Children and adolescents with ASD were defined as those with ASD diagnosis codes (F84.0, F84.1, F84.5, F84.8, and F84.9) between January 1, 2002 and December 31, 2019. As of March 2022, the total population of Korea was 52,762,651, of which 9,187,211 (17.4%) were ⩽19 years of age. The number of children and adolescents with ASD ⩽19 years of age was 63,054, corresponding to 0.7% of the population ⩽ 19 years of age. COVID-19 patients were defined as those with a COVID-19 diagnostic code (U07.1) according to the Korean Standard Classification of Diseases-7, which is a modified version of the International Classification of Diseases, 10th Revision.

Data collection

Data regarding sex, age, insurance type, and residential area were collected from the NHIS database. Insurance type served as a proxy for the economic level of the study participants, who were classified into two groups: NHIS beneficiaries and Medical Aid recipients. Residential areas were divided into the Seoul metropolitan area, Daegu and Gyeongsangbuk province, and other areas according to the level of the COVID-19 epidemic. Comorbidities were estimated using the Charlson Comorbidity Index (CCI), which is an index that predicts the risk for death within 1 year of hospitalization according to the type(s) and condition(s) of comorbidities (Sundararajan et al., 2004). Disability was identified using the National Disability Registry. The World Health Organization ordinal scale was used to assess the severity of infection, which was divided into four categories: ambulatory (score 1 and 2); hospitalized, mild disease (scores 3 and 4); hospitalized, severe disease (scores 5–7); and death (score 8) (WHO R&D Blueprint novel Coronavirus, 2020). Deaths from COVID-19 were defined as death after being hospitalized with a diagnosis of COVID-19 (Korea Centers for Disease Control and Prevention, 2022). The length of admission was defined as the period of hospitalization for the main diagnosis of COVID-19 after the initial diagnosis of COVID-19. The study protocol was approved by the Institutional Review Board (IRB) of Seoul National University Bundang Hospital (IRB number X-2109-709-902).

Statistical analysis

Characteristics of the total population, children and adolescents without ASD, and those with ASD are expressed as mean with standard deviation or number and percentage. Prevalence was calculated as the number of COVID-19 patients per 100,000, and case fatality rate was calculated as the number of deaths among COVID-19 patients. Descriptive statistics were compared using the two-tailed Student’s t-test or analysis of variance for continuous variables, and the χ2 test for categorical variables. All tests were two-tailed, and differences with p < 0.05 were considered to be statistically significant. SAS Enterprise Guide version 8.2 (SAS Institute, Inc., Cary, NC, USA) was used for statistical analysis.

Results

Baseline characteristics and distribution of patients with COVID-19

As of March 31, 2022, of the total population of 52,762,651, the population ⩽ 19 years of age was 9,187,211 (17.4%) in Korea. Among the population ⩽19 years of age, 402,499 (4.4%) were positive for COVID-19 at least once. Of the 9,187,211 individuals ⩽19 years of age, 63,054 (0.7%) had ASD. Of the 9,124,157 children and adolescents without ASD, 399,942 (4.4%) were positive for COVID-19, and 2557 (4.1%) of 63,054 children and adolescents with ASD were positive, resulting in fewer COVID-19 infections among those with ASD (p < 0.001).

Among children and adolescents with ASD, males outnumbered females by a factor of 2.9 (46,905 vs 16,149, respectively), and the proportion of male and female in COVID-19 patients (1921 vs 636) among children and adolescents with ASD was not significantly different compared to the overall children and adolescents with ASD under 19 years of age. (p = 0.38). For children and adolescents both with and without ASD, the proportion of those with COVID-19 was higher in the 0–4 years’ age group and 5–9 years’ age group (p < 0.001). The proportion of Medical Aid recipients was 6.5% among children and adolescents with ASD and 2.2% among those without ASD. The proportion of Medical Aid was similar for children and adolescents with and without COVID-19 in children and adolescents both with and without ASD. According to region, the proportion of COVID-19 patients was higher in the Seoul metropolitan area than the proportion of the population ⩽ 19 years of age among children and adolescents with ASD (60.6%) and in children and adolescents without ASD (59.8%). When the CCI was high, both children and adolescents with ASD (1.7% for CCI ⩾ 3) and those without ASD (0.5% for CCI ⩾ 3) had a higher proportion of children and adolescents with COVID-19 (Table 1).

Table 1.

Baseline characteristics of study participants.

Total population Children and adolescents with ASD Children and adolescents without ASD
Aged ⩽19 COVID-19 patients aged ⩽19 p-value Aged ⩽19 COVID-19 patients aged ⩽19 p-value Aged ⩽19 COVID-19 patients aged ⩽19 p-value
Total, N (%) 9,187,211 (100%) 402,499 (100%) 63,054 (100%) 2557 (100%) 9,124,157 (100%) 399,942 (100%)
Sex, N (%) <0.001 0.38 <0.001
 Male 4,735,106 (51.5%) 213,832 (53.1%) 46,905 (74.4%) 1921 (75.1%) 4,688,201 (51.4%) 211,911 (53%)
 Female 4,452,105 (48.5%) 188,667 (46.9%) 16,149 (25.6%) 636 (24.9%) 4,435,956 (48.6%) 188,031 (47%)
Age, N (%) <0.001 <0.001 <0.001
 0–4 1,876,570 (20.4%) 93,128 (23.1%) 6172 (9.8%) 336 (13.1%) 1,870,398 (20.5%) 92,792 (23.2%)
 5–9 2,339,088 (25.5%) 118,978 (29.6%) 20,491 (32.5%) 1006 (39.3%) 2,318,597 (25.4%) 117,972 (29.5%)
 10–14 2,308,035 (25.1%) 90,338 (22.4%) 18,444 (29.3%) 676 (26.4%) 2,289,591 (25.1%) 89,662 (22.4%)
 15–19 2,663,518 (29%) 100,055 (24.9%) 17,947 (28.5%) 539 (21.1%) 2,645,571 (29%) 99,516 (24.9%)
Type of insurance, N (%) <0.001 0.68 <0.001
 National Health Insurance 8,981,318 (97.8%) 392,985 (97.6%) 58,934 (93.5%) 2395 (93.7%) 8,922,384 (97.8%) 390,590 (97.7%)
 Medical Aid 205,893 (2.2%) 9514 (2.4%) 4,120 (6.5%) 162 (6.3%) 201,773 (2.2%) 9,352 (2.3%)
Region, N (%) <0.001 <0.001 <0.001
 Seoul metropolitan area 4,585,604 (49.9%) 240,757 (59.8%) 32,286 (51.2%) 1550 (60.6%) 4,553,318 (49.9%) 239,207 (59.8%)
 Daegu and Gyeongsangbuk province 866,331 (9.4%) 31,253 (7.8%) 6041 (9.6%) 228 (8.9%) 860,290 (9.4%) 31,025 (7.8%)
 Other areas 3,735,276 (40.7%) 130,489 (32.4%) 24,727 (39.2%) 779 (30.5%) 3,710,549 (40.7%) 129,710 (32.4%)
Charlson Comorbidity Index, N (%) <0.001 <0.001 <0.001
 0 5,864,740 (63.8%) 235,987 (58.6%) 39,486 (62.6%) 1487 (58.2%) 5,825,254 (63.8%) 234,500 (58.6%)
 1–2 3,279,348 (35.7%) 164,494 (40.9%) 22,706 (36%) 1,027 (40.2%) 3,256,642 (35.7%) 163,467 (40.9%)
 ⩾3 43,123 (0.5%) 2,018 (0.5%) 862 (1.4%) 43 (1.7%) 42,261 (0.5%) 1,975 (0.5%)
Disability <0.001 0.53 <0.001
 No 9,096,907 (99%) 399,010 (99.1%) 31,967 (50.7%) 1,312 (51.3%) 9,064,940 (99.4%) 397,698 (99.4%)
 Yes 90,304 (1%) 3489 (0.9%) 31,087 (49.3%) 1245 (48.7%) 59,217 (0.7%) 2244 (0.6%)
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ASD: autism spectrum disorder; COVID-19: coronavirus disease 2019.

Prevalence of COVID-19

The prevalence of COVID-19 in the total population ⩽19 years of age was 4381 per 100,000 children and adolescents. It was 4055 per 100,000 among children and adolescents with ASD, which was lower than that in children and adolescents without ASD (4383 per 100,000; p < 0.001). Among children and adolescents with ASD, both males (4096 vs 4520; p < 0.001) and females (3938 vs 4239; p = 0.008) had a lower prevalence than those without ASD. According to age, the prevalence was higher among children and adolescents with ASD than in those without ASD at 0–4 years of age (5444 vs 4961; p < 0.001); however, at 5–9 years of age, the prevalence was marginally significantly lower (4909 vs 5088; p = 0.07), 10–14 years of age (3665 vs 3916; p = 0.003), and 15–19 years of age (3003 vs 3762; p < 0.001) were also significantly lower. Both NHIS beneficiaries and Medical Aid recipients had a lower prevalence of ASD than those without ASD (p < 0.001). Children and adolescents with ASD had a lower prevalence of COVID-19 in the Seoul metropolitan area and other areas (p < 0.001); however, there was no significant difference between Daegu and Gyeongsangbuk province (p = 0.05). Children and adolescents with ASD had a higher prevalence than those without ASD when the CCI score was ⩾3 (4988 vs 4673, p = 0.001) or for those with disabilities (4005 vs 3789; p = 0.01) (Table 2).

Table 2.

Prevalence of COVID-19 infection among aged 19 or under.

Total population Children and adolescents with ASD Children and adolescents without ASD p-value*
All 4381 4055 4383 <0.001
Sex
 Male 4516 4096 4520 <0.001
 Female 4238 3938 4239 0.008
Age
 0–4 4963 5444 4961 <0.001
 5–9 5087 4909 5088 0.07
 10–14 3914 3665 3916 0.003
 15–19 3756 3003 3762 <0.001
Type of insurance
 National Health Insurance 4376 4064 4378 <0.001
 Medical Aid 4621 3932 4635 <0.001
Region
 Seoul metropolitan area 5250 4801 5253 <0.001
 Daegu and Gyeongsangbuk province 3608 3774 3606 0.05
 Other areas 3493 3150 3496 <0.001
Charlson comorbidity index
 0 4024 3766 4026 0.003
 1–2 5016 4523 5019 <0.001
 ⩾3 4680 4988 4673 0.001
Disability
 No 4386 4104 4387 0.002
 Yes 3864 4005 3789 0.01
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ASD: autism spectrum disorder; COVID-19: coronavirus disease 2019

*

The p-value was obtained by comparing the prevalence of COVID-19 among children and adolescents with ASD and children and adolescents without ASD.

Severity of COVID-19

A total of 634 (24.8%) children and adolescents with ASD and 85,974 (21.5%) without ASD were hospitalized. Hospitalized patients with mild disease, who did not require oxygen or required oxygen therapy below the nasal prong, were 628 (24.6%) in the ASD group and 85,920 (21.5%) in those without ASD. Patients hospitalized for severe disease requiring oxygen therapy more than high flow were 6 (0.2%) with ASD and 50 (0.01%) without ASD. There were six deaths among children and adolescents without ASD (Figure 1, Table 3).

Figure 1.

Figure 1.

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Prevalence, Hospitalization rate, and case fatality rate of COVID-19 infection.

Table 3.

Severity of COVID-19 infection among age 19 or under.

COVID-19 patients with ASD COVID-19 patients without ASD p-value
(N = 2557) (N = 399,942)
Severity, N (%) <0.001
 Ambulatory state 1923 (75.2%) 313,966 (78.5%)
 Hospitalized mild disease 628 (24.6%) 85,920 (21.5%)
 Hospitalized severe disease 6 (0.2%) 50 (0.01%)
 Death 0 (0%) 6 (0.002%)
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ASD: autism spectrum disorder; COVID-19: coronavirus disease 2019.

Length of hospital stay for COVID-19

The mean length of hospital stay for those with ASD was 2.3 (4.4) days, while the mean length of stay for those without ASD was 2.0 (4.1) days. For inpatients, the mean length of stay was 9.5 (3.6) days for children and adolescents with ASD, and 9.4 (3.3) days for those without ASD. There was no significant difference between the groups (p = 0.48). The number of patients hospitalized for 1–14 days and 15–28 days was 597 (23.4%) and 36 (1.4%), respectively, among children and adolescents with ASD, and 82,946 (20.7%) and 2787 (0.7%) in those without ASD, respectively (Table 4).

Table 4.

Length of admission due to COVID-19 infection.

COVID-19 patients with ASD COVID-19 patients without ASD p-value
(N = 2557) (N = 399,942)
Length of admission, N (%) <0.001
 0 1923 (75.2%) 313,968 (78.5%)
 1–14 597 (23.4%) 82,946 (20.7%)
 15–28 36 (1.4%) 2787 (0.7%)
 ⩾28 1 (0.04%) 241 (0.06%)
 Mean (SD)—all patients 2.3 (4.4) 2.0 (4.1) <0.001
 Mean (SD)—only hospitalized patients 9.5 (3.6) 9.4 (3.3) 0.48
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ASD: autism spectrum disorder; COVID-19: coronavirus disease 2019; SD: standard deviation.

Discussion

In this study, there was a lower prevalence of COVID-19 among children and adolescents with ASD than in those without ASD, although those 0–4 years of age, residents of Daegu and Gyeongsangbuk province, those with a CCI score ⩾3, and children and adolescents with disabilities, had a higher prevalence of COVID-19 than those without ASD. Children and adolescents with ASD were more severely affected than those without ASD, and hospitalization for 1–14 days and 15–28 days was slightly greater, on average, although not substantially different. Only children and adolescents without ASD died; however, because the number was very small, it was difficult to determine whether the difference was statistically significant (Figure 1).

A previous study reported that individuals with ASD had a slightly higher prevalence of COVID-19 than the general population, especially among children and adolescents, and were more likely to have severe disease (Krieger et al., 2021). A study from the United States found that patients with intellectual disabilities or developmental disabilities along with ASD had higher hospitalization rates and longer length of hospital stay due to COVID-19 than those without disease(s) (Karpur et al., 2022). In a study involving patients with intellectual or developmental disability (IDD), including ASD, the prevalence of COVID-19 was 1.28 times higher than in those without IDD (Lunsky et al., 2022). The higher prevalence among ASD patients in previous studies can be explained in terms of the behavioral characteristics of autism. This may be because it was difficult for individuals with ASD to follow quarantine rules such as social distancing and personal hygiene due to aggression, low communication skills, and insufficient attention (Eshraghi et al., 2020; Hollis et al., 2021). In addition, ASD-related facilities, such as educational institutions and group homes, can also be risk factors for acquiring COVID-19 (Bergman et al., 2021; Gurdasani et al., 2021).

In contrast, our study found that the prevalence of COVID-19 was lower among children and adolescents with ASD. Before the outbreak of the Omicron variant, the overall prevalence of COVID-19 in Korea was low, and strict quarantine restrictions were imposed. Since the beginning of the COVID-19 pandemic, Korea has relied on preventive testing, immediate tracking, and treatment, known as the “3T strategy” (test-track-treatment) (Na et al., 2020). In addition, the difference between the results of our study and previous studies may be due to differences between adults and children and adolescents. During the COVID-19 pandemic, schools almost exclusively conducted online classes, or online classes with intermittent attendance at school. Even after lowering quarantine measures against COVID-19, preventive tests were performed on a regular basis in high-risk group facilities such as schools, and mental health and long-term care facilities (Korea Centers for Disease Control and Prevention, 2021). As a result, the low prevalence of COVID-19 among children and adolescents with ASD in Korea is believed to be a result of a combination of reduced social activities and quarantine policies. Furthermore, because Korea has fewer schools and facilities (i.e. personal care, social training, and skilled nursing facility) for children and adolescents with ASD than other countries, those with ASD have fewer social contacts than even before the COVID-19 pandemic (Kim et al., 2019; Lee & Yun, 2019). In addition, it has been reported that most adults with ASD were not fully vaccinated, therefore, the COVID-19 prevalence is higher among those with ASD (Lunsky et al., 2022). Because vaccination was introduced late in children and adolescents, this difference may not have been clear in children and adolescents.

The severity of COVID-19 has been reported to be greater among individuals with ASD in previous studies. Several studies have reported that individuals with ASD experience higher hospitalization rates, longer length of admission, and more frequent use of invasive mechanical ventilation and intensive care unit admission due to COVID-19 than the general population (Karpur et al., 2022; Koyama et al., 2022). In a study that analyzed 35,898,076 people with disabilities, those with ASD and IDD were 9 times more likely to be hospitalized for COVID-19 infection and were hospitalized 6 times longer than those without ASD and IDD (Karpur et al., 2022). The results of our study are in accordance with those reported in previous studies. It is a well-known fact that the severity and risk of death from COVID-19 increase with age (Guan et al., 2020). Previous studies have only included adults, or most of the subjects were adults. Therefore, the results of studies on children and adolescents with a relatively low risk of severity may be different (Karpur et al., 2022; Koyama et al., 2022; Lunsky et al., 2022).

The increased disease severity can be attributed to immunological factors. Congenital infection, activation of maternal immunity and transplacental antibodies are associated with the pathophysiology of ASD and often with co-occurring medical conditions that affect the immune system (Fernandes & Kwak, 2022; Lima et al., 2020). In addition, individuals with ASD have an increased likelihood of experiencing “cytokine storms” due to the increased levels of pro-inflammatory cytokines, (Lima et al., 2020) which can result in more severe outcomes (Lin et al., 2020). Some studies have shown that low melatonin levels among individuals with ASD may also increase their susceptibility to SARS-CoV-2 infection (Anderson & Reiter, 2020; Brown et al., 2021).

Furthermore, how Korea responds to COVID-19 patients is related to the higher rate of hospitalizations among those with ASD. The Korea Infectious Disease Response Manual for the Disabled requires that special attention be devoted to individuals with ASD who have limited communication ability and have difficulty in providing sufficient information and understanding, and consider them a priority for hospitalization (Ministry of Health and Welfare, 2021). Meanwhile, beginning in December 2021, all confirmed COVID-19 patients in Korea are treated at home, with only critically ill patients being admitted to hospital (Central Disease Control Headquarters, Central Disaster Management Headquarters, 2021). Children and adolescents with ASD may have a higher hospitalization rate than the general population because it is assumed that undergoing therapy at home is challenging due to communication issues.

Results of this study revealed a relatively low case fatality rate, with only six deaths in the population ⩽19 years of age. Owing to the small number of cases, it was difficult to determine the relationship between ASD and death due to COVID-19 in children and adolescents. In previous studies, adults, children and adolescents with ASD or IDD exhibited greater mortality or case fatality rates (Henderson et al., 2022; Koyama et al., 2022). The case fatality rate was higher in the IDD group than in the non-IDD group in a study that analyzed children and adolescents separately; however, the number of deaths was very low (1–2 deaths per group), similar to our study (Turk et al., 2020). In a recent study, the risk factors for COVID-19 infection in people with IDD receiving residential support services were increased age, Down syndrome, increased number of residents, and chronic kidney disease. Heart disease was a risk factor for COVID-19 death (Landes et al., 2021). The underlying medical condition is one of the important risk factors. Approximately 9.2% of COVID-19 patients among school-age children and adolescents with underlying diseases in the United States were children and adolescents with disability, including ASD (Leeb et al., 2021). In a study that analyzed six hospitals in the United States, 20.2% of children and adolescents under the age of 18 hospitalized for COVID-19 had neurologic or developmental conditions including ASD. In addition, if these underlying medical conditions were present, the length of hospital stay and the number of intensive care unit (ICU) hospitalizations increased. However, similar to our study, there were only 11 deaths in this study out of 713 total participants (Wanga et al., 2021).

COVID-19 mortality rates increase with age, and other comorbidities that could increase the risk of COVID-19 also rise with age. As a result, children and adolescents with ASD have significantly lower COVID-19 mortality rates than adults. Age is a strong risk factor for COVID-19 infection and death in the general population as well as in those with ASD. Therefore, it is considered that a large-scale study is needed to investigate the mortality rate of children and adolescents in the future.

Our study has a strength in that it used nationally representative data from virtually all children and adolescents with ASD in Korea. This is meaningful in situations where data regarding COVID-19 health outcomes of children and adolescents with ASD are scarce. Furthermore, because the government covers all COVID-19-related hospitalizations, with no out-of-pocket costs to patients, the hospitalization rate is less influenced by socioeconomic factors (Lee et al., 2021). On the other hand, the prevalence may be an underestimate of the actual prevalence because an individual who has not been tested for COVID-19, even if they exhibit symptoms, is not counted as a COVID-19 patient. The validity of the ASD diagnosis is one of our limitations. There is no precise information in our data about who entered the diagnostic code. In Korea, psychiatric care is available in primary care settings without a referral, and the public is aware that a psychiatrist makes the diagnosis of ASD (Korea National Health Insurance Service and Health Insurance Review and Assessment Service, National Health Insurance Statistical Yearbook. 2021;1.). Therefore, the majority of diagnoses are assumed to have been made in psychiatry.

Conclusion

Children and adolescents with ASD in Korea exhibited a lower prevalence, greater disease severity, and no significant difference in hospitalization length than those without ASD. The results can be partially explained by the implementation of Korea’s COVID-19 quarantine policy, which resulted in a small number of COVID-19 patients. However, it is also assumed to be influenced by a decrease in social contacts as a result of the absence of facilities and services for children and adolescents with ASD. Building and supporting facilities and services for children and adolescents with ASD are vital, as are maintaining facilities and services in the event of an infectious disease outbreak.

Acknowledgments

We would like to thank the National Health Insurance Service (NHIS) for sharing such invaluable national health insurance database.

Footnotes

Author contributions: Beomjun Kang, Jieun Yun, Jae-ryun Lee, Hyejin Lee, and Jin Yong Lee devised the original study concept; Jae-ryun Lee and Jin Yong Lee participated in data acquisition had full access to all data in the study, and take responsibility for the integrity of the data and the accuracy of the data analyses. Beomjun Kang and Jae-ryun Lee performed statistical analyses and interpreted the data. Beomjun Kang, Jieun Yun, Jae-ryun Lee, Hyejin Lee, and Jin Yong Lee provided intellectual contributions and critically revised the manuscript. Beomjun Kang and Jieun Yun drafted the manuscript, and all authors read, edited, and approved the manuscript submitted for publication. In addition, all authors agree to accept equal responsibility for the accuracy of the content of the article.

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.

Community involvement statement: Not applicable.

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