Re‐infection in COVID‐19: Do we exaggerate our worries?

Abstract

Background Protective long‐term immunity following coronavirus disease 2019 (COVID‐19) is unclear. The study evaluated the relationship between the vaccination status and risk factors in the re‐infection of patients with a diagnosis of COVID‐19 who reported to the Public Health Management System in a province in south‐eastern Turkey. Methods Patients with positive results for the severe acute respiratory syndrome coronavirus 2 by the real‐time reverse transcription polymerase chain reaction (RT‐PCR) test in respiratory samples were defined as confirmed cases. Reinfection was diagnosed in cases with COVID‐19 real‐time RT‐PCR positivity, with or without COVID‐19–like symptoms, in at least 90 days after the first infection/disease. Results A total of 58 811 patients with the diagnosis of COVID‐19 from March 11, 2020, to August 31, 2021, were included in the study. Re‐infection was detected in 421 (0.7%) of all patients. The mean age of the cases was 38.0±16.0 years, and 51% of them were female. Eight (2.0%) of the cases resulted in death due to re‐infection. No hospitalization or mortality was observed in fully vaccinated patients. Additionally, none of the mortal cases had completed the vaccination schedule. Conclusions We are concerned that the re‐infection rates and mortality may increase due to new variant strains. Vaccination is the greatest weapon against progression to critical illness in re‐infections, even with existing mutations. Therefore, it is important for those without a full vaccination schedule to be vaccinated, even if they have been previously infected.

Risk of reinfection and disease after SARS‐CoV‐2 primary infection: Meta‐analysis

“…Of the 3282 papers initially retrieved, we included 91 cohort studies evaluating the onset of reinfection, severe and very severe/lethal COVID‐19 among 15,034,624 previously infected subjects (Figure 1), either among health care workers (27 publications; n = 37,598 2,8,9,15,17,24,36,38,42–59 ) or in the general population (67 publications; n = 14,997,026 3–7,10,12,16–23,25–27,43,49,60–106 ).…”

“…Overall, a total of 158,478 reinfections were recorded among the 15,034,624 subjects with a previous infection, 2–10,12,13,15–27,36,38,42–107 corresponding to a pooled rate of 0.97% (95% CI: 0.71%–1.27%—Table 1; Figure 2). The summary rate of reinfection rose to 1.07% (95% CI: 0.73%–1.46%) when only the 69 datasets with a more conservative time lag of ≥90 days between the two episodes were considered 3–6,8–10,12,18–23,25,26,36,42–44,46–50,52–56,59,61–65,67–69,72–84,86,87,89,91–96,98,101,103,105–107 and it slightly varied by reinfection definition criteria (0.93% vs 1.01% when considering studies with high vs low risk of misclassification). The risk of reinfection was higher among health care workers as compared to the general population (1.20% vs 0.90), and among females (0.79% vs 0.55% among males), although these estimates showed largely overlapping confidence intervals.…”

“…In the 59 available datasets, 2,3,5,6,10,16–22,25–27,36,44,46–59,63–67,69,71–74,79,82,84–87,90,93–95,99–104 a total of 1380 severe COVID‐19 diseases were diagnosed among 5,006,604 subjects with a previous infection, corresponding to a pooled rate of 0.02% (95% CI: 0.00%–0.04%—Table 1). This rate did not substantially vary when only the studies with longer time lag were considered, while it increased—still, however, remaining below 0.1%—when only the studies that used CDC criteria to define reinfections were included (summary rate 0.07%; 0.04%–0.10%).…”

“…As shown in Table S1, most of the included studies ( n = 43) were carried out in Europe, 2,4–10,12,15,17,18,21,24,26,36,38,44,46–51,58,66,69,71,72,75,81,85–88,91–93,95,99,102 24 in the USA, 20,22,23,25,42,43,57,59,63,67,77,79,82–84,89,90,97,98,103,105–107 18 in Asia 3,16,19,27,45,52–54,56,60,62,64,65,70,73,74,100,101 and the remaining six in South America or South Africa 61,68,80,94,96,104 . The mean age of the participants ranged from 15 to 87 years, and the average follow‐up ranged from 29 to 371 days.…”

“…Interestingly, and in line with previous studies, 71,96 we found some degree of variation in reinfection rates across geographical areas. Besides the genetic pattern, the main potential explanations include differences in the detection process caused by the adoption of diverse testing policies, diagnostic methods and health‐seeking behaviours, 65,96 and the fact that countries have been sequentially hit by different variants of SARS‐CoV‐2 120 . Indeed, the mutual combination of these factors may explain, at least in part, the spatial unevenness of SARS‐CoV‐2 spread, which has been observed even at a sub‐national level 96,121 …”