Infection Care Group, Department of Microbiology, St George's Hospital, London, UK.
Infection Care Group, Department of Microbiology, St George's Hospital, London, UK.
J Hosp Infect. 2023 Mar;133:62-69. doi: 10.1016/j.jhin.2022.12.014. Epub 2023 Jan 9.
The impact of nosocomial SARS-CoV-2 infections has changed significantly since 2020. However, there is a lack of up-to-date evidence of the epidemiology of these infections which is essential in order to appropriately guide infection control policy.
To identify the secondary attack rate of SARS-CoV-2 infection and associated mortality across different variants of concern.
A single-centre retrospective study of all nosocomial SARS-CoV-2 exposure events was conducted between 31 December 2020 and 31 December 2021. A secondary attack rate was calculated for nosocomial acquisition of SARS-CoV-2 infection and time to positivity. Positive contacts were assessed for all-cause 30-day mortality.
A total of 346 sequential index exposure events were examined, and 1378 susceptible contacts identified. Two hundred susceptible contacts developed SARS-CoV-2 infection (secondary attack rate of 15.5%). The majority of index cases (59%) did not result in any secondary SARS-CoV-2 infection. Where close contacts developed SARS-CoV-2 infection, 80% were detected within the first five days since last contact with the index case. The overall associated mortality among positive contacts across 2021 was 9%, with an estimated reduction of 68% when comparing periods of high Omicron versus Alpha transmission.
Our findings describe that most SARS-CoV-2 infections are detected within five days of contact with an index case; we have also demonstrated a considerably lower mortality rate with the Omicron variant in comparison to previous variants. These findings have important implications for informing and supporting infection control protocols to allow movement through the hospital, and ensure patients access care safely.
自 2020 年以来，医院获得性 SARS-CoV-2 感染的影响发生了显著变化。然而，目前缺乏有关这些感染的流行病学的最新证据，而这些证据对于适当指导感染控制政策至关重要。
确定不同关注变异株的 SARS-CoV-2 感染的二次感染率和相关死亡率。
对 2020 年 12 月 31 日至 2021 年 12 月 31 日期间发生的所有医院获得性 SARS-CoV-2 暴露事件进行了一项单中心回顾性研究。计算了医院获得性 SARS-CoV-2 感染的二次感染率和阳性时间。对所有原因的 30 天死亡率评估了阳性接触者。
共检查了 346 个连续的索引暴露事件，确定了 1378 个易感接触者。200 个易感接触者发生了 SARS-CoV-2 感染（二次感染率为 15.5%）。大多数索引病例（59%）没有导致任何继发性 SARS-CoV-2 感染。在密切接触者发生 SARS-CoV-2 感染的情况下，80%是在与索引病例最后一次接触后的前五天内检测到的。2021 年阳性接触者的总相关死亡率为 9%，与高奥密克戎与阿尔法传播期相比，估计死亡率降低了 68%。
我们的研究结果表明，大多数 SARS-CoV-2 感染是在与索引病例接触后五天内检测到的；与之前的变异株相比，我们还证明了奥密克戎变异株的死亡率明显降低。这些发现对于为感染控制协议提供信息和支持，以允许在医院内移动，并确保患者安全获得护理具有重要意义。
