Fakhroo Aisha, AlKhatib Hebah A, Al Thani Asmaa A, Yassine Hadi M
Research and Development Department, Barzan Holdings, Doha 7178, Qatar.
Biomedical Research Center, Qatar University, Doha 2713, Qatar.
Vaccines (Basel). 2021 Oct 12;9(10):1168. doi: 10.3390/vaccines9101168.
The COVID-19 pandemic is still posing a devastating threat to social life and economics. Despite the modest decrease in the number of cases during September-November 2020, the number of active cases is on the rise again. This increase was associated with the emergence and spread of the new SARS-CoV-2 variants of concern (VOCs), such as the U.K. (B1.1.7), South Africa (B1.351), Brazil (P1), and Indian (B1.617.2) strains. The rapid spread of these new variants has raised concerns about the multiple waves of infections and the effectiveness of available vaccines. In this review, we discuss SARS-CoV-2 reinfection rates in previously infected and vaccinated individuals in relation to humoral responses. Overall, a limited number of reinfection cases have been reported worldwide, suggesting long protective immunity. Most reinfected patients were asymptomatic during the second episode of infection. Reinfection was attributed to several viral and/or host factors, including (i) underlying immunological comorbidities; (ii) low antibody titers due to the primary infection or vaccination; (iii) rapid decline in antibody response after infection or vaccination; and (iv) reinfection with a different SARS-CoV-2 variant/lineage. Infections after vaccination were also reported on several occasions, but mostly associated with mild or no symptoms. Overall, findings suggest that infection- and vaccine-induced immunity would protect from severe illness, with the vaccine being effective against most VOCs.
新冠疫情仍在对社会生活和经济构成毁灭性威胁。尽管2020年9月至11月病例数略有下降，但活跃病例数再次上升。这种增加与新出现的严重急性呼吸综合征冠状病毒2（SARS-CoV-2）变异株（VOC）的出现和传播有关，如英国（B1.1.7）、南非（B1.351）、巴西（P1）和印度（B1.617.2）毒株。这些新变异株的迅速传播引发了人们对多轮感染以及现有疫苗有效性的担忧。在本综述中，我们讨论了既往感染和接种疫苗个体中与体液反应相关的SARS-CoV-2再感染率。总体而言，全球报告的再感染病例数量有限，表明具有长期保护性免疫。大多数再感染患者在第二次感染期间无症状。再感染归因于多种病毒和/或宿主因素，包括：（i）潜在的免疫合并症；（ii）由于初次感染或接种疫苗导致抗体滴度较低；（iii）感染或接种疫苗后抗体反应迅速下降；以及（iv）感染不同的SARS-CoV-2变异株/谱系。接种疫苗后感染的情况也有多次报道，但大多与轻微症状或无症状相关。总体而言，研究结果表明，感染和疫苗诱导的免疫可预防重症，疫苗对大多数VOC有效。
