Background The aim was to evaluate the necessity of coronavirus disease 2019 (COVID-19) vaccination in persons with prior COVID-19. Methods Employees of the Cleveland Clinic working in Ohio on 16 December 2020, the day COVID-19 vaccination was started, were included. Anyone who tested positive for COVID-19 at least once before the study start date was considered previously infected. One was considered vaccinated 14 days after receiving the second dose of COVID-19 mRNA vaccine. Cumulative incidences of COVID-19, symptomatic COVID-19, and hospitalizations for COVID-19 were examined over the next year. Results Among 52 238 employees, 4718 (9%) were previously infected and 36 922 (71%) were vaccinated by the study’s end. Cumulative incidence of COVID-19 was substantially higher throughout for those previously uninfected who remained unvaccinated than for all other groups, lower for the vaccinated than unvaccinated, and lower for those previously infected than those not. Incidence of COVID-19 increased dramatically in all groups after the Omicron variant emerged. In multivariable Cox proportional hazards regression, both prior COVID-19 and vaccination were independently associated with significantly lower risk of COVID-19. Among previously infected subjects, a lower risk of COVID-19 overall was not demonstrated, but vaccination was associated with a significantly lower risk of symptomatic COVID-19 in both pre-Omicron (HR, .60; 95% CI, .40–.90) and Omicron (HR, .36; 95% CI, .23–.57) phases. Conclusions Both previous infection and vaccination provide substantial protection against COVID-19. Vaccination of previously infected individuals does not provide additional protection against COVID-19 for several months, but after that provides significant protection at least against symptomatic COVID-19.

中文翻译：

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已感染 COVID-19 的人有必要接种 2019 年冠状病毒病 (COVID-19) 疫苗


背景 目的是评估既往患有 COVID-19 的人接种 2019 冠状病毒病 (COVID-19) 疫苗的必要性。方法 2020 年 12 月 16 日（即开始接种 COVID-19 疫苗的当天）在俄亥俄州工作的克利夫兰诊所的员工被纳入其中。在研究开始日期之前至少一次检测出 COVID-19 呈阳性的任何人都被视为以前感染过。其中一人在接受第二剂 COVID-19 mRNA 疫苗 14 天后被认为已接种疫苗。对明年的 COVID-19、有症状的 COVID-19 和因 COVID-19 住院的累积发病率进行了检查。结果 在研究结束时，52 238 名员工中，有 4718 人 (9%) 曾感染过疫苗，36 922 人 (71%) 已接种疫苗。对于那些以前未感染但未接种疫苗的人来说，COVID-19 的累积发病率明显高于所有其他群体，接种疫苗的人比未接种疫苗的人低，而以前感染过的人比未接种疫苗的人低。 Omicron 变种出现后，所有群体的 COVID-19 发病率均急剧上升。在多变量 Cox 比例风险回归中，既往 COVID-19 和疫苗接种均与显着降低的 COVID-19 风险独立相关。在之前感染过的受试者中，并未证明总体上 COVID-19 的风险较低，但在 Omicron 之前的受试者中，疫苗接种与有症状的 COVID-19 风险显着降低相关（HR，0.60；95% CI，0.40–. 90) 和 Omicron (HR, .36; 95% CI, .23–.57) 阶段。结论 既往感染和疫苗接种均可提供针对 COVID-19 的实质性保护。 对先前感染的个体进行疫苗接种并不能在几个月内提供针对 COVID-19 的额外保护，但在此之后至少可以针对有症状的 COVID-19 提供显着的保护。