Reinfections Are More Frequent Than Currently Considered in Countries With High Incidence of Coronavirus Disease 2019 (COVID-19) Cases Due to Stringent Definitions

Clinical Characteristics and Outcomes of Patients With SARS-CoV-2 Reinfection

“…The natural history of the disease remains poorly understood, and newer variants posing a threat to the population are even less understood. 2,3 During the initial phases of the pandemic, it was thought that natural immunity from a previous infection would protect against reinfection. 4 Despite the addition of live attenuated vaccines, we have learned that reinfection is still possible, primarily driven by mutated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains.…”

Confirmed Severe Acute Respiratory Syndrome Coronavirus 2 Reinfections After a Second Wave With Predominance of Lambda in Lima and Callao, Peru

“…This constitutes the largest series of SARS-CoV-2 reinfections confirmed through genomic sequencing in Latin America. We have previously addressed the issue of an existing gap in the quantification of the real number of reinfections occurring in the community, due to diagnostic constraints [ 10 ]. However, we were able to report 30 cases of reinfection during the second wave of infections in the capital of Peru.…”

“…We included subjects with 2 episodes of laboratory-confirmed SARS-CoV-2 infection by reverse-transcriptase polymerase chain reaction (RT-PCR) with 90 or more days between both episodes and presence of 2 different genetic clades of the virus between the first and second samples, according to the PANGOLIN case classification system registered in Nextstrain and GISAID [ 10 ].…”

“…To identify cases, we use a national database (from the Information System of the National Network of Public Health Laboratories of Peru [NetLabv2]) for the following: (1) positive cases; (2) possible reinfections, which were defined as patients with a positive test (serological [if not vaccinated], antigenic, or molecular) and a second positive test (antigenic or molecular) after >90 days; and (3) probable reinfections, defined as patients with 2 tests positive molecular tests after >90 days (as suggested above) for resource-limited settings [ 10 ]. The definitions of possible reinfections and probable reinfections were used as a search strategy until the cases were prioritized for sequencing, and these were also based on current Centers for Disease Control and Prevention definitions [ 13 ].…”

“…However, this varied when populations that were highly exposed at the end of the first wave, such as Manaus in Brazil, presented high rates of infection during their “second wave”. These ravaging successive waves showed that reinfection cases were possible with new variants and waning of immunity, indicating that the scarcity of scientific reports did not reflect the real epidemiology of reinfections [ 10 ].…”