In December 2019, a virus of unknown origin was initially identified in Wuhan, China. Subsequently, the virus was classified as part of the novel enveloped RNA betacoronavirus family named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its associated disease coronavirus disease 2019 (COVID-19). The World Health Organization has declared it as a pandemic, with the current confirmed cases and deaths across the globe of over 24,000,000 and 800,000 respectively.
This unprecedented rise in cases has caused fear of the possibility of re-infection amongst the public and healthcare workers. Therefore, researchers sought out to understand and investigate the mechanism of COVID-19 re-infection.
Research on Coronavirus reinfection
Prior studies have attempted to report cases of re-infection but have failed to provide any support with the genetic sequencing of the samples. Moreover, such studies have demonstrated to be associated with prolonged shedding of the virus rather than actual cases of confirmed re-infection. For example, a study by Li et al. revealed that the duration of viral shedding was approximately eleven days after the onset of sickness. Patients who recovered from COVID-19 have demonstrated to shed viral fragments and subsequently observed to have tested positive for antibodies but not for the live virus through PCR testing. As such, early data on this indicates a lack of scientific evidence, and scientists have continued to direct their efforts into understanding the immunity of the human body against re-infection.
A recent study by Kai-Wang To and colleagues published on August 15th was the first confirmed case of re-infection by whole genome sequencing in a patient. A 33-year old male from Hong Kong was first infected in March where he presented with symptoms of fever, sore throat, and cough for 3 days and was later admitted. Diagnosis of COVID-19 infection was confirmed via oropharyngeal saliva RT-PCR and subsequently, the patient’s symptoms subsidized, and he tested negative twice prior to discharge. Approximately 5 months later, the patient was re-infected and tested positive by oropharyngeal saliva RT-PCR, although asymptomatic. Whole-genome sequencing performed on both saliva specimens (March and August) exhibited that the two viral genomes belonged to different strains and lineages of the virus with 23 different nucleotides between the two strains.
Russian governor of the region of Tyva in Siberia was re-infected
After this recent study, news outlets have reported that the governor of the region of Tyva in Siberia was re-infected with COVID-19 three months after the initial onset. A 54-year old male, Sholban Kara-Ool, originally presented with symptoms of chest pain at the end of May and three months later he presented with headaches and subsequently tested positive. Although not much is known about the evidence behind this news, this has instigated concern among scientists around the world.
The COVID-19 pandemic is a dynamic, evolving situation as we continue to learn more and more about how humans develop immunity against COVID-19 after infection. Although there have been multiple studies to suggest possible re-infection, to date there is only one confirmed documented case of re-infection. Consequently, physicians should not take the lack of supporting data lightly as there is a dire need to stay alert and vigilant regarding the possibility of re-infection, especially with different viral lineages.