Assessment of the risk of SARS-CoV-2 reinfection in an intense re-exposure setting

Abstract

Background: Reinfection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been a subject of debate. We aimed to assess the risk and incidence rate of documented SARS-CoV-2 reinfection in a large cohort of laboratory-confirmed cases in Qatar. Methods: All SARS-CoV-2 laboratory-confirmed cases with at least one PCR positive swab that is ≥45 days after a first positive swab were individually investigated for evidence of reinfection, and classified as showing strong, good, some, or weak/no evidence for reinfection. Risk and incidence rate of reinfection were estimated. Results: Out of 133,266 laboratory-confirmed SARS-CoV-2 cases, 243 persons (0.18%) had at least one subsequent positive swab ≥45 days after the first positive swab. Of these, 54 cases (22.2%) had strong or good evidence for reinfection. Median time between first and reinfection swab was 64.5 days (range: 45-129). Twenty-three of the 54 cases (42.6%) were diagnosed at a health facility suggesting presence of symptoms, while 31 (57.4%) were identified incidentally through random testing campaigns/surveys or contact tracing. Only one person was hospitalized at or following time of reinfection swab, but still had relatively mild infection. No deaths were recorded. Risk of reinfection was estimated at 0.04% (95% CI: 0.03-0.05%) and incidence rate of reinfection was estimated at 1.09 (95% CI: 0.84-1.42) per 10,000 person-weeks. Conclusions: SARS-CoV-2 reinfection appears to be a rare phenomenon suggestive of a strong protective immunity against reinfection that lasts for at least a few months post primary infection.

SARS-CoV-2 infection hospitalization, severity, criticality, and fatality rates

“…This is in agreement with the diagnosis (detection) rate estimated here at 12.1% (95% CI: 12.0-12.1%), as well as growing evidence from other countries indicating that only one in every 10 infections was ever diagnosed [24,[30][31][32][33]. The totality of evidence on the Qatar epidemic also indicates that most infections were asymptomatic or minimally mild to be diagnosed [5][6][7][8][9][34][35][36]. For instance, a national SARS-CoV-2 PCR survey found that 58.5% of those testing PCR positive reported no symptoms within the preceding two weeks of the survey [5].…”

Added value of anti-SARS-CoV-2 antibody testing in a Flemish nursing home during an acute COVID-19 outbreak in April 2020

“…For staff members, the presence of IgG most likely means they are unlikely to get reinfected in the next months and spread the virus. While it has been demonstrated using full-length genome sequencing that individuals can be reinfected [17,18], a recent study in Qatar where an estimated 50% of the population had been infected with SARS-CoV-2 suggests the rate of reinfection in an intense re-exposure setting is very low (less than 0.1% suspected reinfections 1.5 to 4 months after the first infection) [19]. From an epidemiological perspective, staffing nursing homes with staff who tested positive for IgG could help bring down the high case-fatality rates [20].…”

Understanding the implications of SARS-CoV-2 re-infections on immune response milieu, laboratory tests and control measures against COVID-19

“…Nevertheless, re-infection with other coronaviruses can occur with stable and high antibody titres. In a study where 133,266 laboratory-confirmed cases were evaluated with 243 positive swabs after 45 days of their first SARS-CoV-2 infection, it was found that 54 of these cases had re-infection considering their Ct values or symptoms of COVID-19 [ 71 ]. However, these cases cannot be determined to be true re-infection because neither WGS nor viral culture was used to identify these cases.…”

“…However, these cases cannot be determined to be true re-infection because neither WGS nor viral culture was used to identify these cases. Yet, the risk and incidence of re-infection was estimated to be 0.04% (95% CI: 0.03%–0.05%) and 1.09 (95% CI: 0.84–1.42) per 10,000 persons respectively [ 71 ].…”