投稿分類 防護措施

主委發表種類: 壁報

投稿標題(中): 台灣某醫院的 SARS-CoV-2 抗體血清研究：評估對抗 Omicron 變異株的保護效果

投稿標題(英): A Sero-protection study of SARS-CoV-2 Antibodies in a Tertiary Care Hospital in Taiwan: Implications for Protection against the Omicron Variants

投稿摘要: Introduction:
Taiwan's stringent infection control and prevention (ICP) measures, established since the SARS era, have effectively limited widespread infections within healthcare institutions (HCIs). To be coherent with the global COVID-19 situation, Taiwan initiated a loosening of its ICP policy. reclassifying severe COVID-19 as a fourth-tier reported infectious disease from May 1, 2023. Concurrently, the Taiwan Central Epidemic Command Center of COVID-19 was deactivated. Since early October 2023, a new wave of COVID-19 infection emerged in Taiwan. But, hybrid immunity against ongoing circulating Omicron variants remains unknown.
Since January 2020 , Taiwan has implemented relevant strategies of ICP measures, including surveillance, allocation of personal protective equipment, and COVID-19 advance education. In Taiwan, the main policies of ICP measures include quarantine, rolling definition for case reporting and detection, contact tracing, wearing of surgical mask, social distancing, and isolation of patients with COVID-19. Taiwan also integrated SARS-CoV-2 genomic surveillance into COVID-19 surveillance to detect variants of concern. Based on the viral surveillance, For locally-acquired cases, Epsilon variant was detected during January to February 2021 in a hospital-related outbreak, Alpha variant during April to August 2021 in the first wave of sustained community transmission, Delta variant during June to December in a few outbreaks. Importantly, Before and after the ICP policies were relaxed, the seroprevalence was 0.05%, which suggested the majority of the population including the HCWs are not exposed to virus and the only protective immunity is from the vaccination. Therefore, a cross-sectional seroprevalence study was performed among healthcare workers (HCWs) in a tertiary care hospital in Taiwan from August 1, 2022, to January 1, 2023. We aimed to (1) evaluate the antibody response mainly from COVID-19 vaccination against Omicron subvariants BA.1, BA.4, and BA.5 without any prior infection; (2) the effectiveness of ICP measures and vaccination policies and their implementation in hospital settings in Taiwan.
Methods:
A cross-sectional serology study was conducted in Taiwan to investigate the seroprevalence rates of Omicron subvariants BA.1, BA.4, and BA.5 among HCWs. A total of 777 HCWs participated in this study. A structured questionnaire was collected to obtain the epidemiological characteristics and risk factors for potential exposure. Enzyme-linked immunosorbent assay used Architect SARS-CoV-2 IgG and IgG II Quant assay (Abbott-NP, Abbott, Chicago, IL) to detect antibody responses. Serum samples were selected for protection against Omicron subvariants BA.1, BA.4, and BA.5 by using a pseudotyped-based neutralization assay.
Results:
More than 99% of the participants had received SARS-CoV-2 vaccination. Overall, 57.66% had been infected with SARS-CoV-2, with some being asymptomatic. The SARS-CoV-2 Anti-Spike S1 protein IgG (Anti-S) distribution was 40000 AU/mL for 20.2% (157/777) of participants, with a mean  standard deviation of 23442  22086. The decay curve for Anti-S was less than 20000 AU/ml after 120 days. The probability curve of 50% neutralization showed an Anti-S of 55000 AU/ml. The optimum Anti-S was 41328 AU/mL, with 86.1% sensitivity and 63.5% specificity.
Discussion and conclusion:
Our study found that only 20.2% of HCWs had achieved seroprotection against these Omicron subvariants BA.1, BA.4 and BA.5. Before the ICP policies were relaxed, the COVID-19 seroprevalence was 0.05%. As the majority of Taiwan's population relies primarily on vaccination to provide protection due to the lack of hybrid immunity, we provide two proactive perspective to reduce the morbidity and mortality of COVID-19 based on the current Taiwan COVID-19 situation.
Vaccine policies have been established but demographic variations exist worldwide. The key metric is vaccination coverage. As winter approaches, vaccination policies differ between the United States, European countries, and Taiwan. Importantly, there are no incentives for vaccination policies for HCWs. Provided that HCIs are primary sites for treating COVID-19 cases, enhancing the COVID-19 vaccination coverage among HCWs is a pressing need.
ICP measures are well established in HCIs but exhibit variability in their implementation. The critical factor is the execution rate of COVID-19 ICP measures. In Taiwan, HCIs are tasked with developing ICP standards that gradually align with influenza prevention protocols. On the contrary, the United States, CDC guidance, and WHO continue to advise necessary protective equipment or procedures to prevent hospital-acquired COVID-19 infection and isolation to prevent nosocomial infection. Hospitalized individuals, typically in fragile elderly, face elevated risks of severe COVID-19 when exposed to COVID-19 within HCIs. Consequently, a distinct and more stringent approach to ICP is essential to minimize harm in HCIs.

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