Epidemiological characteristics of HIV and AIDS in mainland China: a 16-Year national surveillance analysis (2005–2020)

Abstract

Background

This study aimed to describe the epidemiological trends and regional/age distributions of HIV and AIDS in China from 2005 to 2020 and provide scientific reference for the government about HIV and AIDS prevention and control.

Methods

Data on HIV and AIDS cases reported encompassing various age groups and 31 provinces, autonomous regions, and municipalities in mainland China from 2005 to 2020 were sourced from the Data Center of China Public Health Science.

Results

A total of 570,576 AIDS cases were identified and reported in China from 2005 to 2020. The reported AIDS incidence, AIDS-related mortality, HIV incidence, and HIV mortality increased from 0.4324/100,000, 0.1012/100,000, 1.9437/100,000, and 0.0216/100,000 in 2005, respectively, to 4.4283/100,000, 1.3405/100,000, 6.3839/100,000, and 1.2884/100,000 in 2020, respectively. The corresponding average annual growth rates were 16.33%, 18.19%, 7.83%, and 29.40%. The reported HIV and AIDS stage-specific incidence and mortality significantly differed by geography and age. The reported HIV incidence peaked among young adults (20–34 years old), and the > 50 age group showed the highest HIV mortality, AIDS-related mortality and AIDS incidence.

Conclusions

The HIV and AIDS epidemic in China showed a gradual rising trend over the years and exhibited geographical and age distribution difference. Young adults and older populations were the major populations in the HIV and AIDS epidemic in China. Health education, interventions, and testing efforts targeting these key populations should be strengthened. Building a resilient HIV and AIDS treatment service system is essential for ensuring stable HIV and AIDS services during public health emergencies.

Clinical trial number

Not applicable.

Introduction

The prevalence of human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) remains a tremendous challenge to public health authorities, especially in developing countries. The Joint United Nations Programme on AIDS (UNAIDS) reported 40.8 million people living with HIV (PLHIV), 630,000 AIDS-related deaths, and 1.3 million people newly infected with HIV worldwide in 2024 (UNAIDS, 2025) [1]. AIDS is a chronic disease that seriously affects public health worldwide. Since the first reported Chinese AIDS case in 1985, the disease has gradually spread; 62,167 new AIDS cases and 18,819 new deaths from all causes of AIDS were recorded in 2020, making AIDS a common infectious disease that is the sixth in incidence and the highest in mortality in China [2]. HIV and AIDS control is still a significant challenge in China. With the fast economic development, ethnic diversity, extensive territory, regime shifts, sexual attitude changes, and AIDS treatment, new epidemiological characteristics of HIV and AIDS in China have emerged. Sexual transmission has replaced unsafe intravenous drug use as the predominant route of HIV transmission in China [3]. Men who have sex with men (MSM), female sex workers (FSWs), and person who uses drugs (PDU) are considered key populations of HIV infection in China [4]. After Qiao et al. [5] reported the epidemiology of the regional and age differences of HIV and AIDS in China from 2004 to 2016, our study provides an updated descriptive evaluation. The Chinese government has also promulgated a series of policies for HIV and AIDS prevention and control, such as the Implementation Plan for Preventing the Spread of AIDS (2019–2022) [2]. During the same period, the COVID-19 pandemic has disrupted healthcare systems globally, and HIV testing and treatment services in China were also affected. However, data on how the pandemic influenced HIV transmission patterns still limited, new and updated epidemiological data about AIDS in China are lacking. Our study extends the temporal scope to 2020, analyzing the most recent 4-year data (2017–2020) unavailable in previous studies. The findings provide updated regional and age-stratified data describing the trends of HIV/AIDS epidemiology in China.

Materials and methods

Data source

This study utilized surveillance-based metrics for HIV and AIDS in mainland China from 2005 to 2020. All data were obtained from the Data Center of China Public Health Science (https://www.phsciencedata.cn/Share/index.jsp). The data provided the annual numbers of newly reported HIV cases, newly reported AIDS cases, reported HIV deaths, reported AIDS deaths, reported HIV incidence, reported AIDS incidence, and related mortality rates, stratified by age group and province (31 provinces, autonomous regions, and municipalities).

Based on the specific definitions used by the Chinese Center for Disease Control and Prevention (https://www.caivd-org.cn/article.asp?id=13662), these data represent reported cases (people newly diagnosed and reported to the surveillance system) and should not be interpreted as new HIV infections or new AIDS cases, which may differ due to underreporting or delayed diagnosis. Reported HIV incidence: newly reported HIV cases per 100,000 population; reported AIDS incidence: newly diagnosed AIDS cases per 100,000 population. Regarding the number of deaths and the mortality rate, (1) AIDS-related deaths: all-cause deaths reported during the year among cumulative reported AIDS patients (people diagnosed with AIDS), regardless of the underlying cause of death. This includes not only deaths that occurred in the current year but also historical deaths identified during follow-up visits and reported in the current year. It excludes deaths among HIV-infected people who had not yet developed AIDS; (2) HIV deaths: refers to deaths occurring in people living with HIV (PLHIV, infected but had not yet progressed to the AIDS stage, regardless of the cause of death); (3) AIDS-related mortality: AIDS deaths per 100,000 population; and (4) HIV mortality: HIV deaths per 100,000 population. The dataset did not contain any patient-specific information, and the data were publicly accessible. Hence, ethical approval for its use was not required.

Data processing and inclusion/exclusion criteria

The downloaded dataset was imported into Microsoft Excel for data cleaning and screening. Inclusion criteria: reported HIV or AIDS cases/deaths from mainland China between 2005 and 2020 with complete information. Exclusion criteria: cases with incomplete geographical data (missing or invalid province) or missing age information.

Years of life lost (YLL) estimation

YLL was calculated by aggregating each death multiplied by its age-specific standard life expectancy. This measure of premature death was calculated as.

where N = deaths from cause c (age a, sex s, and year t), L= standard loss function specifying years of life lost for a death at age a for sex s [6]. A theoretical minimal risk reference life table was utilized to calculate the YLL of HIV/AIDS from 2005 to 2020.

Average annual growth rate (AAGR) estimation

AAGR was calculated as the geometric mean of n annual growth rates (𝑝_𝑡):

Statistical analysis

Data cleaning, exclusion, YLL calculation (by year), and AAGR calculation (by year and province) were performed in Microsoft Excel. Statistical analyses were conducted utilizing SPSS version 22.0 (IBM Corp., Armonk, NY, USA). To compare differences across provinces and age groups, we performed one‑way ANOVA. Data were visualized using Origin version 2021 (OriginLab Corp., Northampton, MA, USA), Graph Pad Prism 8.0 (Graph Pad Prism, San Diego, CA, USA).

Provincial maps were created using ArcGIS version Pro 2022 (ESRI, Redlands, CA, USA, 2022). Each map used graduated colors with manually defined intervals (either 6 or 7 classes, depending on the data distribution) and no normalization was applied. Spatial joins were applied to merge attribute data with the provincial shapefile.

p < 0.05 indicated statistical significance.

Results

Epidemic situation

From 2005 to 2020, China reported 570,576 AIDS cases (annual incidence: 2.6052/100,000). After 172 cases with incomplete geographical data were excluded, 570,404 cases were included in the analysis. During this period, the number of newly reported AIDS cases, AIDS-related deaths, HIV cases, and HIV deaths in mainland China exhibited an overall increasing trend, with AAGRs of 13.48%, 21.85%, 8.20%, and 65.10%, respectively. The reported AIDS incidence, AIDS-related mortality, HIV incidence, and HIV mortality showed consistent annual increases with AAGRs of 16.33%, 18.19%, 7.83% and 29.40%, respectively. Nevertheless, the above indicators showed a mild decline during the COVID-19 pandemic (Table 1; Fig. 1).

Table 1.

The reported HIV and AIDS incidence, mortality and years of life lost in China from 2005 to 2020

Year	AIDS cases			AIDS-related death				HIV cases			HIV death
	Number	Incidence (1/100,000)	Growth rate	Number	Mortality (1/100,000)	Growth rate	YLL	Number	Incidence (1/100,000)	Growth rate	Number	Mortality (1/100,000)	Growth rate	YLL
2005	5621	0.4324	-	1316	0.1012	-	69581.71	25,266	1.9437	-	281	0.0216	-	14852.83
2006	6671	0.5102	0.1798	1331	0.1018	0.0055	68803.69	31,591	2.4160	0.2430	392	0.0300	0.3868	21064.51
2007	9727	0.7400	0.4504	3904	0.2970	1.9177	6500433.65	32,906	2.5034	0.0361	1515	0.1153	2.8445	81098.43
2008	10,059	0.7613	0.0288	5389	0.4079	0.3733	264850.58	41,466	3.1383	0.2536	3214	0.2432	1.1105	168024.92
2009	13,281	1.0001	0.3136	6596	0.4967	0.2178	325385.88	44,192	3.3277	0.0603	5142	0.3872	0.5918	256479.11
2010	15,982	1.1974	0.1973	7743	0.5801	0.1680	377714.58	45,640	3.4194	0.0276	6605	0.4949	0.2781	329410.56
2011	20,450	1.5251	0.2737	9224	0.6879	0.1858	441616.93	52,746	3.9336	0.1504	8620	0.6428	0.2991	412467.42
2012	41,929	3.1119	1.0405	11,575	0.8590	0.2487	539576.9	58,399	4.3343	0.1019	11,467	0.8510	0.3238	544658.56
2013	42,286	3.1230	0.0036	11,437	0.8447	-0.0167	521260.84	63,498	4.6895	0.0820	10,974	0.8105	-0.0476	509189.72
2014	45,145	3.3313	0.0667	12,030	0.8877	0.0510	540146.25	74,048	5.4641	0.1652	11,224	0.8282	0.0219	499790.84
2015	50,330	3.6940	0.1089	12,755	0.9362	0.0546	564818.37	81,696	5.9962	0.0974	12,072	0.8860	0.0698	528915.39
2016	54,360	3.9656	0.0735	14,091	1.0280	0.0980	610683.53	87,764	6.4025	0.0678	12,833	0.9362	0.0566	544690.3
2017	57,194	4.1450	0.0452	15,251	1.1053	0.0752	651714.39	95,549	6.9247	0.0816	15,467	1.1209	0.1973	648406.02
2018	64,170	4.6195	0.1145	18,780	1.3519	0.2231	789246.15	104,838	7.5472	0.0899	19,354	1.3932	0.2429	810290.01
2019	71,204	5.0986	0.1037	20,999	1.5036	0.1122	845059.89	103,350	7.4004	-0.0195	21,407	1.5328	0.1002	857088.06
2020	62,167	4.4283	-0.1315	18,819	1.3405	-0.1085	739622.44	89,620	6.3839	-0.1374	18,088	1.2884	-0.9242	698680.56

YLL, years of life lost

Note: AIDS deaths, all-cause deaths reported during the year among cumulative reported AIDS patients, regardless of the underlying cause of death, and exclude deaths among HIV-infected individuals who had not progressed to AIDS

Fig. 1.

During 2005–2020, the reported HIV and AIDS stage-specific incidence and mortality in China increased

Regional distribution

Statistical analysis revealed significant interprovincial disparities (all p < 0.001) in the spatial distribution of newly reported HIV cases, newly reported AIDS cases, and related deaths across China from 2005 to 2020. Concurrently, significant disparities were also observed in the reported HIV and AIDS stage-specific incidence and mortality during this period. According to the above indicators, Guangxi, Guangdong, Sichuan, Chongqing, Guizhou, Yunnan, Xinjiang, Henan, Hunan, and Jiangxi provinces are among the high-risk regions (Figs. 2 and 3). All regions demonstrated positive AAGR across the reported HIV and AIDS stage-specific incidence and mortality (Fig. 4).

Fig. 2.

During 2005–2020, the average number (year) of reported AIDS cases (a), HIV cases (b), AIDS-related deaths (c) and HIV deaths (d) across regions in China

Fig. 3.

During 2005–2020, the reported HIV and AIDS stage-specific incidence and mortality varied widely by district in China

Fig. 4.

During 2005–2020, average annual growth rates of HIV and AIDS stage-specific incidence and mortality in Chinese provinces

Age distribution

Individuals aged 20–50 years accounted for 53.12%–69.97% of all newly reported HIV and AIDS cases and related deaths, indicating a great burden on this population. Furthermore, statistical comparisons showed nonsignificant differences between the 20–50 and > 50 age groups for reported AIDS cases (p = 0.0844), AIDS-related deaths (p = 0.4575), and HIV deaths (p = 0.8792). By contrast, the differences among the other comparison groups were statistically significant (all p < 0.01) (Fig. 5). Significant differences in reported HIV and AIDS stage-specific incidence and mortality were also observed among different age groups (all p < 0.01). In addition, we found following bimodal age distribution patterns in the above indicators. Newly reported HIV incidence peaked among young adults (20–34 years old, particularly 20–30 years old), and the > 50 age group showed the highest HIV mortality, AIDS-related mortality and AIDS incidence, with all indicators exhibiting age-progressive trends (Fig. 6).

Fig. 5.

During 2005–2020, the average number (year) of reported AIDS cases (a), HIV cases (b), AIDS-related deaths (c) and HIV deaths (d) across different age groups in China

Fig. 6.

During 2005–2020, the reported HIV and AIDS stage-specific incidence and mortality varied widely by age in China

Discussion

Since the first reported case of AIDS in 1981, this pandemic has spread rapidly in the world [7]. Globally, 91.4 million people have been infected with HIV, and 44.1 million people have died due to HIV [8]. HIV prevalence varies greatly across countries and regions; for instance, in 2019 HIV prevalence in South Africa were14,251/100,000, whereas the rates in Asia were 100/100,000 [9]. In China, our study shows the reported HIV incidence annually increased from 1.9437/100,000 in 2005 to 6.3839/100,000 in 2020, with an AAGR of 7.83%. In addition, the reported AIDS incidence, AIDS-related mortality, and HIV mortality continued to increase every year: from 0.4324/100,000, 0.1012/100,000, and 0.0216/100,000 in 2005, respectively, to 4.4283/100,000, 1.3405/100,000, and 1.2884/100,000 in 2020, respectively, with AAGRs of 16.33%, 18.19%, and 29.40%, respectively. Hundreds of HIV and AIDS prevention and control policies have been issued in China over the last few decades. Examples were as follows: notification of HIV status in 1986, implementation and revocation of China’s travel ban on PLHIV, the Blood Donation Law of 1998, China’s 5-Year Action Plans for the Containment and Control of HIV/AIDS, the “Four Frees and One Care” HIV/AIDS free treatment policy in 2003, and the China Action Plan for the Thirteenth Five-Year Plan for Combating and Prevention of AIDS [10, 11]. Although HIV/AIDS burden in China were relatively lower than those of cancer [12], the number of cases cannot be underestimated. In addition, the disease burden was relatively heavy because of the large population base. In 2020, there were 62,167 newly reported AIDS cases (with 18,819 deaths) and 25,266 newly reported HIV cases (with 18,088 deaths) in China; the YLL of AIDS- and HIV-related deaths were 739,622.44 and 698,680.56, respectively, accounting for 1.4% of the global AIDS-related YLL (53,543,400 years) [13]. Despite its lower overall burden compared with global AIDS and noncommunicable diseases, AIDS had the highest mortality rate among China’s notifiable infectious diseases [14], underscoring its significant impact on public health in China.

HIV transmission in China has evolved from injection drug use, to blood transmission in the mid-1990s, and now to predominantly sexual contact [15]. In addition to wide variations on a global scale, HIV and AIDS burden showed large regional differences in China. In our study, high reported HIV and AIDS stage-specific incidence and mortality were concentrated in southwest and south regions (Sichuan, Chongqing, Guizhou, Yunnan, Guangxi, and Guangdong), Xinjiang, Henan, Hunan, and Jiangxi. In the southwest and south regions, geographical proximity to the golden triangle, easy access to drugs, a large number of PDU, and sexual modifications have been documented. Rural-to-urban migrant workers in Sichuan, Chongqing, and Guizhou result in multiple sexual partners and transactional sex, elevating the risk of HIV transmission [16]. Based on these findings, HIV and AIDS control should be strengthened in PDU, sex workers, and migrant workers. In Henan, high HIV and AIDS burden were observed in our data. Illegal paid blood collection occurred in the early 1990s in this province [17], the reasons include HIV testing for previous paid blood people in 2004, as well as excessively long latency period of AIDS, insufficient treatment, aging of HIV-infected individuals, and population mobility [18]. Furthermore, disparities in economic development and public health spending across regions directly affect access to antiretroviral therapy (ART), influencing HIV and AIDS incidence. Healthcare resources have a certain inhibitory effect on the distribution of HIV and AIDS incidence in China; whereas GDP, per capita disposable income, and population density show a relatively weak impact [19]. Developed and more public medical resources regions (such as Beijing) typically have specialized designated hospitals offering comprehensive and professional care, whereas relatively scarce public medical resources regions mainly depend on infectious disease specialist hospitals, resulting in treatment challenges for PLHIV [19]. In Xinjiang and Jiangxi, increases in reported HIV and AIDS incidence and mortality were observed. Previous studies have reported that these regions face economic poverty, limited healthcare, and low HIV testing and disclosure [20]. Tibet’s low fatality rates were also observed. Factors such as low rates of prior HIV testing, remote geographical location, limited medical conditions, and religious belief were reported in the region [20].

More than 90% of HIV infections among children worldwide were transmitted via mother to child [21, 22]. China initiated a project for the prevention of mother-to-child HIV transmission in 2003 and then issued “the Implementation Plan for Prevention of Mother-to-Child Transmission of AIDS, Syphilis and Hepatitis B” [23]. In our study, we found that reported incidence and mortality for both HIV and AIDS were consistently lower in the 0–14 age group, which coincided with the above policies. The reported HIV incidence was highest among individuals aged 20–34 years, previous studies have reported active sexual life and inadequate sex education in this age group, contributing to high-risk behaviors [5]. More than 85% Chinese young people lacked HIV prevention knowledge [24]. College students have limited access to sexual health education, as most colleges in China are unable to proceed sexual health education with an open and inclusive approach [25]. Warner et al. [26] also found that the HIV incidence in the population aged 20–29 years was significantly higher than in the other populations in the USA. With the expansion of ART, the increase in older people with HIV reflects both the ageing of long-term survivors and new infections acquired at older ages [27]. In our study, we also found that individuals aged > 50 years had high reported HIV mortality, AIDS-related mortality and AIDS incidence rate. Recent studies in China revealed the shifting patterns of HIV transmission among older adults. Marriage and heterosexual contact were considered as risk factors for HIV infection in Chinese adults aged ≥ 50 years [28]. Heterosexual transmission is the primary mode of HIV transmission among older males, and one of the important transmission modes is commercial heterosexual contact [29]. Heterosexual transmission within marriage is a common transmission route for women [30]. This phenomenon may be associated with the following behavioral factors: older males prefer the nonuse of condoms and low-cost FSWs than younger males in China, thus increasing the exchange of body fluids with sex workers [31]. A study in a city in southwestern China suggested that 84.7% of old males had experienced commercial sexual intercourse, among whom 87.7% have never used condoms and 37.6% had more than 10 commercial sexes within 1 year [32]. Zhao et al. [33] reported that PLHIV were predominantly male, with over 50% acquiring HIV through casual or commercial sex and significantly higher than younger PLHIV (30%). In addition, inconsistent condom use was more prevalent among older PLHIV (55.9%) than middle-aged PLHIV (45.2%) in most western studies (25%–42%) [33]. Owing to the influence of traditional Chinese culture, Chinese elders had limited HIV education and testing, leading to delays in diagnosis and treatment, and even high mortality. Therefore, early discovery, diagnosis, and treatment could reduce the risk of AIDS transmission, HIV secondary transmission, and AIDS death. China has implemented HIV and AIDS policies that significantly reduced transmission risks (injections, blood transfusions, and mother to child) and mortality. Since the launch of programs for the prevention of mother-to-child HIV transmission, the rate of mother-to-child transmission dropped from 7.1% (2012) to 4.9% (2017). China CARES takes action to enhance HIV/AIDS awareness through publicity and education [34].

Wang et al. [35] found that the new HIV infection rate declined by 5.2450% during the COVID-19 pandemic (2020–2022) compared with previous non-COVID-19 periods (2015–2019), whereas AIDS mortality rose by 14.1076%. Our findings showed the same result during the period of China’s dynamic COVID-zero strategy. First, the strict isolation measures, banning of public gatherings, and closure of entertainment venues greatly reduced sexual partner access and decreased the HIV infection rate or reported HIV case numbers. However, HIV testing accessibility was limited; the reported case numbers might have been underestimated than the actual figure during lockdown periods. Reduced access to HIV counselling might also contribute to the underdiagnosis of HIV during the COVID-19 pandemic [35]. In the first month of COVID-19, almost 2,208 HIV infections and 1,525 AIDS cases were misdiagnosed and underreported [36]. Furthermore, the limited access to anti-HIV drugs due to visiting hospital restrictions increased the risk of AIDS mortality [35]. A February 2020 UNAIDS survey revealed that one-third of PLHIV in China faced imminent ART shortages, and half reported uncertainty about where to obtain their next refill [37]. According to a large survey across 20 countries, 50% of PLHIV reported being unable to remotely access their HIV medication refills [38]. The COVID-19 pandemic exposed vulnerabilities in HIV service systems and prompted China to implement measures to ensure HIV services continuity. During the pandemic, the National Center for AIDS/STD Control and Prevention of China’s CDC issued a policy guaranteeing uninterrupted provision of free ART. Shenzhen maintained its AIDS services through hospital resource reorganization, which include (1) relocating HIV clinics to isolated clean zones to prevent nosocomial infections, (2) implementing telemedicine and drug delivery, and reducing patient visits and COVID-19 exposure [39]. Community-based organizations moved operations online to sustain AIDS services, with 87% establishing hotlines between February and April 2020, and 50% provided HIV self-testing kits and medication delivery services [40]. Therefore, integrating government, hospital, and community resources to establish a resilient HIV treatment service system is vital for maintaining uninterrupted AIDS services during public health emergencies.

Overall, our study identifies three key findings with important implications: (1) a gradual rising trend in HIV and AIDS epidemic in China, particularly in Guangxi, Guangdong, Sichuan, Chongqing, Guizhou, Yunnan, Xinjiang, Henan, Hunan, and Jiangxi; (2) high proportions of reported HIV cases among younger populations and high reported HIV mortality, AIDS-related mortality and AIDS incidence among older populations; and (3) all reported HIV and AIDS related indicators decreased during the COVID-19 outbreak compared to pre-pandemic levels. These findings demand a targeted intervention strategy that includes the following: (1) prioritized resource allocation to high-risk regions and key populations (e.g.,MSM, sex workers, and PUD); (2) age-targeted prevention programs emphasizing youth education and enhanced elderly screening, complemented by behavioral interventions for key populations informed by bio-behavioral survey data; (3) strengthening early detection and treatment should be the cornerstone of China’s HIV and AIDS control efforts; and (4) strengthening multisectoral resource integration to build a resilient HIV and AIDS treatment service system for ensuring stable HIV and AIDS service during public health emergencies.

Despite these meaningful findings, this study had several limitations. First, as a secondary analysis of a single public dataset, the data were fairly limited, we lacked data disaggregated by sex, sexual behaviors, occupation, or socioeconomic status, preventing assessment of key populations (e.g., MSM, sex workers, PUD). Second, because this study is descriptive and uses pre‑computed incidence and mortality from the public dataset, confidence intervals are not reported. The absence of uncertainty quantification is a limitation of this descriptive approach. Third, lacking health resource and socioeconomic data, the link between HIV and AIDS epidemic and economic development or medical resources remains speculative. Fourth, surveillance-related biases (e.g., changes in testing coverage, reporting practices, ART availability, and COVID-19 disruptions) may have influenced reported trends. Fifth, the reported rates are crude and not age-standardized, so comparisons across regions or over time may be affected by differences in age distribution. However, a comprehensive understanding of the epidemic dynamics requires triangulation with complementary data sources, such as bio-behavioral surveys, population size estimations, and special studies. Therefore, we will collect and analyze additional HIV and AIDS data in future research to optimize prevention and control policies.

Abbreviations

HIV

Human immunodeficiency virus

AIDS

Acquired Immune Deficiency Syndrome

UNAIDS

Joint United Nations Programme on AIDS

MSM

Men who have sex with men

FSWs

Female sex workers

YLL

Years of life lost

AAGR

Average annual growth rate

ART

Antiretroviral therapy

PLHIV

People living with HIV

PUD

Person who uses drugs

Author contributions

YY designed research, collected data and wrote the manuscript; JZ and BH analyzed data and helped to draft the manuscript; JL designed research, contributed to reviewed the literature and made revisions related to important intellectual content of the manuscript. All authors issued final approval for the version to be submitted.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Data availability

Publicly available datasets were analyzed in this study. This data can be sourced from the Data Center of China Public Health Science (https://www.phsciencedata.cn/Share/index.jsp).

Declarations

Ethics approval and consent to participate

No ethical permission is required for publicly downloaded data.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.