COVID-19 re-infection by a phylogenetically distinct SARS-coronavirus-2 strain confirmed by whole genome sequencing
Kelvin Kai-Wang To
Ivan Fan-Ngai Hung
Jonathan Daniel Ip
Allen Wing-Ho Chu
Wan-Mui Chan
Anthony Raymond Tam
Carol Ho-Yan Fong
Shuofeng Yuan
Hoi-Wah Tsoi
Anthony Chin-Ki Ng
Larry Lap-Yip Lee
Polk Wan
Eugene Tso
Wing-Kin To
Dominic Tsang
Kwok-Hung Chan
Jian-Dong Huang
Kin-Hang Kok
Vincent Chi-Chung Cheng
Kwok-Yung Yuen
These authors contribute equally.
Corresponding author: Kwok-Yung Yuen, Email:kyyuen@hku.hk, Phone number: (852)-22552413, Carol Yu Centre for Infection, State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong, China
Received 2020 Aug 23.
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Abstract
Background
Waning immunity occurs in patients who have recovered from COVID-19. However, it remains unclear whether true re-infection occurs.
Methods
Whole genome sequencing was performed directly on respiratory specimens collected during two episodes of COVID-19 in a patient. Comparative genome analysis was conducted to differentiate re-infection from persistent viral shedding. Laboratory results, including RT-PCR Ct values and serum SARS-CoV-2 IgG, were analyzed.
Results
The second episode of asymptomatic infection occurred 142 days after the first symptomatic episode in an apparently immunocompetent patient. During the second episode, there was serological evidence of elevated C-reactive protein and SARS-CoV-2 IgG seroconversion. Viral genomes from first and second episodes belong to different clades/lineages. Compared to viral genomes in GISAID, the first virus genome has a stop codon at position 64 of orf8 leading to a truncation of 58 amino acids, and was phylogenetically closely related to strains collected in March/April 2020, while the second virus genome was closely related to strains collected in July/August 2020. Another 23 nucleotide and 13 amino acid differences located in 9 different proteins, including positions of B and T cell epitopes, were found between viruses from the first and second episodes.
Conclusions
Epidemiological, clinical, serological and genomic analyses confirmed that the patient had re-infection instead of persistent viral shedding from first infection. Our results suggest SARS-CoV-2 may continue to circulate among the human populations despite herd immunity due to natural infection or vaccination. Further studies of patients with re-infection will shed light on protective correlates important for vaccine design.
Keywords: COVID-19, SARS-CoV-2, re-infection, whole genome sequencing, D614G