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Epidemiological survey and risk factors for COVID-19 infection among students following downgraded management: A cross-sectional study

Year: 2024

Type: article

Abstract: To the Editor: The Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread worldwide during the coronavirus disease 2019 (COVID-19) pandemic. Experts agree that the Omicron variant is less pathogenic and has a shorter incubation period, making it more likely to cause upper respiratory tract infections. After comprehensive consideration, the National Health Commission of China had renamed the term for COVID-19 from “novel coronavirus pneumonia” to “novel coronavirus infection” on December 26, 2022, and downgraded management from Class A to Class B on January 8, 2023.[1] Although this adjustment is the most significant strategic change in the epidemic prevention and control policy in the last three years, SARS-CoV-2 has not completely disappeared, and some countries are experiencing multiple waves of increased infections. Monitoring the impact of COVID-19 and the effectiveness of prevention and control strategies remains a public health priority. Schools are primary settings for infection transmission during the pandemic due to the high population density.[2] However, most studies have focused on college students, while studies on the entire student community have been scarcely reported. In addition, the different ways of lifestyles of students may lead to different infection conditions. Therefore, it is necessary to investigate the status of infection among students and obtain timely and accurate information on epidemics. The main purpose of this study was to analyze the infection, treatment, and preventive vaccine, and identify factors influencing infection in students in the new situation of Class B management, which may provide a reference basis for scientific decision-making on the prevention of infectious diseases. The Shanxi Provincial Center for Disease Control and Prevention and the Shanxi Medical University conducted an online questionnaire survey specifically designed for COVID-19 policy shifts. The included subjects of this study were students in Shanxi province. The structured questionnaire included information on sociodemographic characteristics, symptoms, treatment, vaccination, and anxiety. Data were collected from January 1 to January 4, 2023. The students who were unable to complete the questionnaire independently can be replaced by their parents to fill in the questionnaire. Quality control covered from questionnaire design, sampling, and data collecting, to data cleaning and analyzing. We deleted invalid questionnaires: completed in a short period, duplicates, or missing items over 50%. Informed consent was obtained through the online survey, and participants remained anonymous. This study was approved by the ethics committee of the Shanxi Medical University (No. 2021GLL173). In total, 116,700 out of 134,766 students completed the questionnaires, yielding a response rate of 86.59%. Overall, a confirmed infection was documented in 72,592 students, with an infection rate of 62.20% (72,592/116,700). Among the students, the infection rate among 20–29-year age group was 64.97% (45,686/70,320), which was higher than that of 3–5-year age group (54.13%, 177/327) and 6–19 age group (58.04%, 26,729/46,053). Of the infected students, the proportion of males accounted for 28.47% (20,666/72,592). In urban areas, the infection rate was 57.03% (30,867/54,122). In rural areas, the infection rate was 66.68% (41,725/62,578). To determine the severity of the infection, we investigated the symptoms of the infected students. A total of 72,569 students (99.97%) declared that they experienced at least one acute symptom, mainly including fever (92.72%, 67,283/72,569), cough (86.94%, 63,090/72,569), fatigue (68.39%, 49,627/72,569), nasal obstruction (65.68%, 47,661/72,569), sore throat (64.07%, 46,493/72,569), runny nose (57.11%, 41,445/72,569), and headaches (56.44%, 40,960/72,569). Among students with fever, 60.57% (40,752/67,283) had a temperature of 38.1–39.0°C, 21.91% (14,743/67,283) had a temperature of 39.1–41.0°C, and less than 0.26% (172/67,283) had a temperature of >41°C. The majority of infected students had symptoms lasting four to seven days, accounting for 47.03% (34,127/72,569). The survey also found that 31.11% (22,577/72,579) of the infected students reported experiencing anxiety, as measured by the Generalized Anxiety Disorder Scale-7 (GAD-7). For treatment, more than 90.96% (66,030/72,592) of infected students opted to self-administer symptomatic medication at home, and less than 3.65% (2651/72,592) sought medical care. The most commonly used medications at home were antipyretics and analgesics (85.53%, 56,475/66,030) and cough medicines (49.93%, 32,971/66,030). Among infected students who visited medical institutions, 67.14% (1780/2651) visited village health clinics, 19.46% (516/2651) visited community health centers/township health centers, and 0.91% (24/2651) visited provincial hospitals. The hospitalization rate for infected students was 0.15% (106/72,592), with most hospitalizations lasting less than seven days. In terms of vaccination, as shown in Figure 1, students who received the fourth COVID-19 vaccine dose had lower infection rates, and the shorter the time since the last vaccination was, the lower the infection rate in age groups of 6–19 and 20–29 years.Figure 1: Infection rate of students with vaccination (A). Infection rate according to the time that elapsed since the last COVID-19 vaccination (B). COVID-19: Coronavirus disease 2019.To elucidate the factors affecting student infection, we further used univariable and multivariable logistic regressions. Students in 20–29-year age group (adjusted odds ratio [aOR]: 1.51, 95% confidence interval [CI]: 1.21–1.89, P <0.001), living in an urban area (aOR: 1.52, 95% CI: 1.49–1.56, P <0.001), and having a chronic condition (aOR: 1.52, 95% CI: 1.32–1.75, P <0.001) were risk factors for infection. Male students had a lower risk of infection (aOR: 0.68, 95% CI: 0.66–0.70, P <0.001). Vaccination with the fourth dose was a protective factor against infection (aOR: 0.46, 95% CI: 0.25–0.87, P = 0.017). There were significant differences in the infection rate according to the time that had elapsed since the last COVID-19 vaccination (P <0.001), and the risk of infection showed a downward trend when the time that had elapsed since the last COVID-19 vaccination was shorter [Supplementary Table 1, https://links.lww.com/CM9/C25]. Subgroup analysis revealed that the risk factors associated with COVID-19 infection were living in an urban area. In age groups of 6–19 and 20–29 years, being female, and having a chronic condition were the risk factors for infection. Our study results revealed a significant protective effect of receiving the fourth dose only among age group of 6–19 years (aOR: 0.26, 95% CI: 0.09–0.71, P = 0.009). It was confirmed that the risk of infection showed a downward trend when the time that had elapsed since the last COVID-19 vaccination was shorter in age groups of 6–19 and 20–29 years [Supplementary Table 2, https://links.lww.com/CM9/C25]. This study demonstrated that the infection rate among age group of 20–29 years was higher than that among age groups of 3–5 and 6–19 years. Being female, living in an urban area, having a chronic condition, and having a longer elapsed time since receiving the last COVID-19 vaccination were risk factors for infection among students after COVID-19 management was downgraded. The high infection rate among students in the age group of 20–29 years may be due to the fact that they were university students and group living created conditions for the spread of infectious diseases. Among the range of measures to prevent the spread of SARS-CoV-2 and ultimately quell the pandemic, vaccination is one of the most cost-effective preventive interventions. The results of our study indicated that vaccination was a protective factor, although the results were not statistically significant for the first three doses. Moreover, the protective effect of vaccination was consistent with previous studies showing that the vaccine efficacy or effectiveness against SARS-CoV-2 infection of any severity is gradually diminishing.[3] Our study found that 31.11% of the infected students had anxiety, which is lower than that of 33% reported by a prior systematic study in Asia.[4] As a special group affected by the pandemic, many students aged 20–29 years experienced anxiety because of the changed delivery and uncertainty of university education, technological concerns about online courses, being far from home, social isolation, and worries about future education and career, so they need more attention from society. Furthermore, post-COVID-19 conditions occur in young people with at least one physical symptom that affects everyday functioning persisting for a minimum duration of 12 weeks after infection.[5] Post-COVID-19 syndrome should not be underestimated and requires appropriate medical strategies. The major limitation of this study is that the data collection method relied on the online questionnaire, which is prone to volunteer and recall biases. Indeed, it is difficult to assess causality using this study design. Funding This study was supported by the National Key Research and Development Program of China (No. 2021YFC2301603), the Major Science and Technology Project of Shanxi Province (Nos. 202102130501003 and 202005D121008), and the Special Foundation on COVID-19 of the Shanxi Health Commission (No. 16). Conflicts of interest None.

Source: Chinese Medical Journal

DOI: 10.1097/cm9.0000000000003158