Association between vaccination status and COVID-19-related health outcomes among community-dwelling COVID-19 patients in Nara, Japan

Impact of COVID-19 vaccination status on hospitalization and disease severity: A descriptive study in Nagasaki Prefecture, Japan

Coronavirus disease 2019 (COVID-19) was extraordinarily harmful, with high rates of infection and hospitalization. This study aimed to evaluate the impact of COVID-19 vaccination status and other factors on hospitalization and disease severity, using data from Nagasaki Prefecture, Japan. Confirmed cases of COVID-19 infection with vaccination status were included and the differences in characteristics between different vaccination statuses, hospitalization or not, and patients with varying levels of disease severity were analyzed. Furthermore, logistic regression was used to calculate odds ratio (ORs) and 95% confidence intervals (CI) to evaluate the association of various factors with hospitalization and disease severity. From March 14, 2020 to August 31, 2022, 23,139 patients were unvaccinated 13,668 vaccinated the primary program with one or two doses, and 4,575 completed the booster. Vaccination reduced the risk of hospitalization with an odd ratio of 0.759 (95% CI: 0.654-0.881) and the protective effect of completed booster vaccination was more pronounced (OR: 0.261, 95% CI: 0.207-0.328). Similarly, vaccination significantly reduced the risk of disease severity (vaccinated primary program: OR: 0.191, 95% CI: 0.160-0.228; completed booster vaccination: OR: 0.129, 95% CI: 0.099-0.169). Overall, unvaccinated, male, elderly, immunocompromised, obese, and patients with other severe illness factors were all risk factors for COVID-19-related hospitalization and disease severity. Vaccination was associated with a decreased risk of hospitalization and disease severity, and highlighted the benefits of completing booster.

Willingness of medical students to work on the COVID-19 frontline during the pandemic in China: A nationwide population-based cross-sectional study

Background

The World Health Organization declared that coronavirus disease 2019 (COVID-19) constitutes an international public health emergency, which has strained health resources. In this study, we aimed to understand medical students' willingness to join the workforce fighting against the COVID-19 pandemic and identify factors associated with their decisions.

Methods

We conducted a nationwide cross-sectional study using the Wen-Juan-Xing platform and a pre-designed questionnaire from 23 March to 19 April 2021. We conducted logistic regression analyses to identify the determinants associated with the willingness.

Results

Among the 5022 medical students, the majority (n = 4289, 85.40%) expressed willingness to work on the COVID-19 frontline. Logistic regression indicated that medical students' willingness to work on the COVID-19 frontline in China was associated with gender, region, reason for choosing medicine, having medical workers in the family, students whose family members, relatives or friends experienced COVID-19, and professional attitude. Females (odds ratio (OR) = 1.305; 95% confidence interval (CI) = 1.100-1.549; P = 0.0023), medical students from urban areas (OR = 1.295; 95% CI = 1.089-1.539; P = 0.0034), medical students whose choice of a medical career was their desire (OR = 1.579; 95% CI = 1.290-1.933; P < 0.0001), medical students whose parents or relatives are medical workers (OR = 1.266; 95% CI = 1.066-1.505; P = 0.0073), medical students whose family members, relatives, or friends have never been infected with COVID-19 (OR = 4.567; 95% CI = 3.002-6.947; P < 0.0001), and medical students with undisturbed of professional attitudes (OR = 4.280; 95% CI = 3.241-5.654; P < 0.0001) showed increased willingness to work on the COVID-19 frontline compared with their counterparts.

Conclusions

Medical students demonstrated a strong willingness to contribute to COVID-19 work during the pandemic in China. The findings may provide valuable information for emergency management so that policymakers can maintain sufficient health resources and provide quality health care in similar health emergencies in the future.

Real-world effectiveness of full and booster mRNA vaccination for coronavirus disease 2019 against disease severity during the delta- and omicron-dominant phases: A propensity score-matched cohort study using the nationwide registry data in Japan

BACKGROUND

To date, few studies from the Asian region have reported the effectiveness of messenger ribonucleic acid coronavirus disease 2019 (COVID-19) vaccines against disease progression and death after hospitalization.

METHODS

We evaluated the data from the COVID-19 registry in Japan during the delta- and omicron-dominant phases. A propensity score-matched cohort study was conducted between the incompletely (0-1 dose) and fully (2 doses) vaccinated groups during the delta-dominant phase and among the incompletely, fully, and booster (3 doses) vaccinated groups during the omicron-dominant phase.

RESULTS

In the delta-dominant phase, 411 pairs were matched. The fully vaccinated group showed a significantly lower oxygen supplementation rate (24.1 % vs. 41.1 %, p < 0.001) but little difference in the mortality rate (2.2 % vs. 2.9 %, p = 0.66). In the omicron-dominant phase, 1494 pairs from the incompletely and fully vaccinated groups, and 425 pairs from the fully and booster vaccinated groups were matched. Full vaccination reduced both the oxygen supplementation rate (18.6 % vs 25.7 %, p < 0.001) and mortality rate (0.7 % vs 2.3 %, p < 0.001). Booster vaccination showed little difference in either the rate of oxygen supplementation (21.2 % vs. 24.7 %, p = 0.25) or mortality (1.2 % vs. 2.6 %, p = 0.21) compared with full vaccination.

CONCLUSIONS

Full vaccination reduced disease severity during the delta- and omicron-dominant phases; booster vaccination did not further enhance the protective effects against disease progression during the omicron-dominant phase compared to full vaccination. Future vaccine strategies and policy decisions should consider preventing infection or disease progression in the target population, as well as the characteristics of the dominant variant in that phase.

Risk of severe COVID-19 in unvaccinated patients during the period from wild-type to Omicron variant: real-world evidence from Japan

BACKGROUND

Many studies have reported that the Omicron variant is less pathogenic than the Delta variant and the wild-type. Epidemiological evidence regarding the risk of severe COVID-19 from the wild-type to the Omicron variant has been lacking.

METHODS

Study participants were COVID-19 patients aged 18 and older without previous COVID-19 infection who were notified to the Nara Prefecture Chuwa Public Health Center from January 2020 to March 2023, during the periods from the wild-type to the Omicron variant. The outcome variable was severe COVID-19 (i.e., ICU admission or COVID-19-related death). The explanatory variable was SARS-CoV-2 variant type or the number of COVID-19 vaccinations. Covariates included gender, age, risk factors for aggravation, and the number of general hospital beds per population. The generalized estimating equations of negative binomial regression models were used to estimate the adjusted incidence proportion (AIP) with 95% confidence interval (CI) for severe COVID-19.

RESULTS

Among 77,044 patients included in the analysis, 14,556 (18.9%) were unvaccinated and 520 (0.7%) developed severe COVID-19. Among unvaccinated patients, the risk of severe COVID-19 increased in the Alpha/Delta variants and decreased in the Omicron variant compared to the wild-type (AIP [95% CI] was 1.55 [1.06-2.27] in Alpha/Delta and 0.25 [0.15-0.40] in Omicron), but differed by age. Especially in patients aged ≥80, there was no significant difference in the risk of severe COVID-19 between the wild-type and the Omicron variant (AIP [95% CI] = 0.59 [0.27-1.29]). Regarding the preventive effect of vaccines, among all study participants, the number of vaccinations was significantly associated with the prevention of severe COVID-19, regardless of variant type. After stratified analyses by age, patients aged ≥80 remained a significant association for all variant types. On the other hand, the number of vaccinations had no association in Omicron BA.5 of patients aged 18-64.

CONCLUSIONS

Patients aged ≥80 had less reduction in risk of severe COVID-19 during the Omicron variant period, and a greater preventive effect of vaccines against severe COVID-19, compared to younger people. Our findings suggest that booster vaccination is effective and necessary for older people, especially aged ≥80.

Vaccination, regular exercise, and prevention of chronic lung disease reduce exacerbation of COVID-19 severity in northern Okinawa, Japan: A cross-sectional study

BACKGROUND

As at June 14, 2023, the coronavirus disease 2019 (COVID-19) pandemic had affected more than 767 million people and caused more than 6.9 million deaths worldwide. This study aimed to clarify the lifestyle factors that influence the exacerbation of COVID-19 severity.

METHODS

This was a cross-sectional study of patients with COVID-19 whose severity classification of "moderate or severe" (COVID-19 exacerbation) was defined as an objective variable. The 1,353 participants were selected from 4,899 patients with COVID-19 between August 10, 2020 and December 10, 2022. Participants who underwent a specific health checkup before the date for a COVID-19 consultation were included. Using binominal logistic regression analysis, we evaluated the odds ratios (ORs) for COVID-19 exacerbation according to lifestyle-related factors. Limitations were discussed using a target trial emulation framework which clarifies problems in observational studies.

RESULTS

The explanatory variables extracted as factors that exacerbated COVID-19 severity were gender (OR [man vs. woman]: 2.533, 95% confidence interval [CI] 1.484-4.322); age (OR [50s vs. 10s, 20s, or 30s]: 4.858, 95% CI 2.319-10.177; OR [60s]: 9.738, 95% CI 4.355-21.777; OR [70s + 80s + 90s]: 8.327, 95% CI 3.224-21.507); and comorbid chronic lung disease (OR ['yes' vs. 'no']: 2.892, 95% CI 1.227-6.818). The explanatory variables extracted as factors that reduce the severity of COVID-19 were hospital consultation year (OR [2022, predominantly Omicron variant prevalent vs. 2020, predominantly Alpha variant prevalent]: 0.180, 95% CI 0.058-0.559); number of vaccinations (OR [2 doses vs. 0 or one doses]: 0.223, 95% CI 0.114-0.436; OR [≥3 doses vs. 0 or one doses]: 0.090, 95% CI 0.035-0.229); regular exercise (exercising ≥2 days/week ≥30 minutes each at an intensity that causes a slight sweat for ≥1 year) (OR ['yes' vs. 'no']: 0.458, 95% CI 0.242-0.866).

CONCLUSIONS

These results suggest the importance of vaccination, regular exercise, and prevention of chronic lung disease as measures against exacerbation of COVID-19 severity.