Impact of COVID-19 Vaccination on Healthcare Worker Infection Rate and Outcome during SARS-CoV-2 Omicron Variant Outbreak in Hong Kong

Impact of coronavirus disease 2019 on the utilization of hospital services and development of optimal pandemic control strategy in Chinese tertiary hospitals during the Omicron wave

BACKGROUND

This study aimed to assess the impact of coronavirus disease 2019 (COVID-19) on hospital service utilization and revenue in Chinese tertiary hospitals and develop an optimal pandemic control strategy (OPCS) for the peak period of the Omicron wave.

METHODS

Retrospective data from three Chinese tertiary hospitals (provincial, city, and county level) were analyzed for three phases: pre-outbreak (Jan-Apr 2019), outbreak (Jan-Apr 2020), and post-outbreak (Jan-Apr 2021). OPCS was developed under the guidance of the China government pandemic control policy during post-break phase of COVID-19. A decision-tree model was constructed to compare OPCS to strict pandemic control strategy during outbreak phase for the hospital service utilization and hospital revenue in a provincial tertiary hospital during the Omicron wave.

RESULTS

Outpatient, emergency room (ER) visits, hospitalizations, and intensive care admissions dropped by 33.8-53.4% during the outbreak, with the provincial hospital being the most affected. Hospital revenue also declined, especially for the provincial hospital (40.1%). Post-outbreak, most services recovered, but ER visits remained lower (11.6% decrease for provincial hospital, 46.5% for county hospital). Total income and expenditure decreased, with the provincial hospital experiencing the most significant revenue reduction (45.7%). OPCS showed greater utilization of medical services (31.6 times more outpatient visits; 1.7 times more inpatient days; 3.4% more surgery volume) and higher revenue (¥220.8 million more) compared to the strict pandemic control strategy.

CONCLUSIONS

COVID-19 measures were associated with less hospital service utilization and revenue in Chinese tertiary hospitals. The developed OPCS in Chinese tertiary hospitals, focusing on isolating infected inpatients but not shutting down the hospital facilities exposed to virus, could be effective in optimizing hospital service utilization and hospital revenue during the Omicron wave.

Epidemiology, risk factors, and vaccine effectiveness for SARS-CoV-2 infection among healthcare workers during the omicron pandemic in Shanghai, China

Background

The COVID-19 pandemic has exposed healthcare workers (HCWs) to serious risk of infection. The aims of our study were to investigate the epidemiological characteristics and risk factors of SARS-CoV-2 infection among HCWs, and evaluate the vaccine effectiveness (VE) during the Omicron pandemic in Shanghai, China.

Methods

Active surveillance of COVID-19 was performed among HCWs who worked in Shanghai General Hospital from December 2022 to January 2023. A case-control study was conducted by questionnaire survey to analyse the infection-related risk factors. A retrospective cohort study was explored to evaluate VE against primary infection.

Results

During the Omicron outbreak, 2,008 of 2,460 (81.6%) HCWs were infected with SARS-CoV-2. The infection rate was higher in women, younger age groups, nurses and medical technicians. Among the 1,742 participants in the questionnaire, 1,463 (84.0%) were tested positive, and 95.1% of them developed symptoms. Most of the infections (53.0%) were acquired outside the hospital. The risk factors associated with higher odds of infection were working in the emergency department (aOR 3.77, 95% CI 1.69-8.38) and medical examination area (aOR 2.47, 95% CI 1.10-5.51). The protective factors associated with lower odds of infection were previous infection with SARS-CoV-2 (aOR 0.01, 95% CI 0-0.07) and receiving four doses of vaccines (aOR 0.40, 95% CI 0.17-0.97). For frontline HCWs, those who had oral-nasal exposure to coworkers were more likely to be infected (aOR 1.74, 95% CI 1.21-2.51). In VE analysis, the risk of primary infection was lower in HCWs who received the emergency heterologous booster (the fourth dose) during the epidemic (aHR 0.25, 95% CI 0.15-0.40), resulting in an adjusted-VE of 75.1%.

Conclusions

In response to future pandemic, it is important for public health policies to aim at protecting HCWs through risk-differentiated infection control measures, strengthening personal protection and recommending vaccination to vulnerable individuals before the arrival of Omicron wave.

Effective vaccination strategies to control COVID-19 in Korea: a modeling study

OBJECTIVES

In Korea, as immunity levels of the coronavirus disease 2019 (COVID-19) in the population acquired through previous infections and vaccinations have decreased, booster vaccinations have emerged as a necessary measure to control new outbreaks. The objective of this study was to identify the most suitable vaccination strategy for controlling the surge in COVID-19 cases.

METHODS

A mathematical model was developed to concurrently evaluate the immunity levels induced by vaccines and infections. This model was then employed to investigate the potential for future resurgence and the possibility of control through the use of vaccines and antivirals.

RESULTS

As of May 11, 2023, if the current epidemic trend persists without further vaccination efforts, a peak in resurgence is anticipated to occur around mid-October of the same year. Under the most favorable circumstances, the peak number of severely hospitalized patients could be reduced by 43% (n=480) compared to the scenario without vaccine intervention (n=849). Depending on outbreak trends and vaccination strategies, the best timing for vaccination in terms of minimizing this peak varies from May 2023 to August 2023.

CONCLUSIONS

Our findings suggest that if the epidemic persist, the best timing for administering vaccinations would need to be earlier than currently outlined in the Korean plan. It is imperative to continue monitoring outbreak trends, as this is key to determining the best vaccination timing in order to manage potential future surges.

The Impact of Vaccination Among Hospitalized Patients with the Diagnosis of COVID-19

Objective

We aimed to investigate the vaccination status and the risk factors for the intensive care unit (ICU) support need of the laboratory-confirmed breakthrough COVID-19 infection inpatients.

Materials and Methods

This multi-center point-prevalence study was conducted on inpatients, divided into two groups as 'fully' and 'partially' vaccinated according to COVID-19 vaccination status.

Results

Totally 516 patients were included in the study. The median age was 65 (55-77), and 53.5% (n=276) of the patients were male. Hypertension (41.9%, n=216), diabetes mellitus (DM) (31.8%, n=164), and coronary artery disease (CAD) (16.3%, n=84) were the predominant comorbidities. Patients were divided into two groups ICU (n=196) and non-ICU (n=301). Hypertension (p=0.026), DM (p=0.048), and congestive heart failure (CHF) (p=0.005) were significantly higher in ICU patients and the median age was younger among non-ICU patients (p=0.033). Of patients, 16.9% (n=87) were fully vaccinated, and this group's need for ICU support was statistically significantly lower (p=0.021).

Conclusion

We conclude that older age, hypertension, DM, CHF, and being partially vaccinated were associated with the need for ICU support. Therefore, all countries should continuously monitor post-vaccination breakthrough COVID-19 infections to determine the national booster vaccine administration approach that will provide vulnerable individuals the highest protection.

Infection of healthcare workers despite a high vaccination rate during the fifth wave of COVID-19 due to Omicron variant in Hong Kong

Background

No nosocomial infection was recorded in our healthcare workers (HCWs) during the early phase of the coronavirus disease 2019 (COVID-19) pandemic. With the emergence of the Omicron variant of increased transmissibility, infection in HCWs occurred as expected. We aimed to study the epidemiology of infection in HCWs and to describe the infection control measures during the outbreak of the Omicron variant.

Methods

With daily rapid antigen testing and molecular confirmation test for COVID-19, infected HCWs were interviewed by infection control nurses (ICNs) to investigate the potential source of infection. The epidemiology of COVID-19 in Hong Kong served as reference.

Results

During the fifth wave of COVID-19 (31 December 2021 to 31 May 2022), 1,200,068 cases were reported (incidence 95 times higher than in preceding waves in Hong Kong; 162,103 vs 1,707 per million population respectively, P<0.001). The proportion of infected HCWs was significantly higher than that of the general population (24.9%, 1,607/6,452 vs 16.2%, 1,200,068/7,403,100 respectively; P<0.01). The proportion of infected non-clinical staff was significantly higher than that of clinical staff (31.8%, 536/1,687 vs 22.5%, 1,071/4,765 respectively; P<0.001). Of 82.8% (1,330/1,607) infected HCWs interviewed by ICNs, 99.5% (1,324/1,330) had been fully vaccinated; 49.5% (659/1,330) had no identifiable source; 40.7% (541/1,330) were probably infected from household members; 9.8% (130/1,330) had possible exposure to confirmed patients or HCWs, but no lapse in infection control measures or inappropriate use of personal protective equipment was recalled.

Conclusion

Omicron variant is highly transmissible such that breakthrough infection occurred despite high level of vaccination.