He returned to Hong Kong from Spain and upon RT-PCR entry screening at the HK airport tested positive again by RT-PCR on Aug 15 (4.5 months after his initial positive test), with Ct=26.7, a fairly high viral load. No symptoms the second time. Hospitalized again. (2/6)
Viral load declined while hospitalized. Tested negative for IgG from hospitalization day 1-3, but seroconverted (became IgG+) on day 5. Sequencing of the virus from March and August saliva samples show two distinct #SARSCoV2 viruses from different clades (V/19A vs G/20A). (3/6) 
Differences between his two #SARSCoV2 strains: an early stop codon in ORF8 that truncates 58 amino acids + 23 mutations, 13 of which cause other amino acid changes in Spike (4 amino acid changes), NP, NSP3, NSP5, NSP6, NSP12, ORF3a, ORF8, and ORF10. (4/6)
If the report is accurate, that the RT-PCR tests were separated by 142 d while 95% of patients are PCR-negative by day 33, that the viral genomes are distinct, and seroconversion occurred during episode 2, suggests reinfection by different #SARSCoV2 strains may be possible.(5/6)
The report appears to be a preprint and needs peer review. But implications are that no one vaccine or herd immunity event may permanently end the pandemic, and investment in testing & vaccination infrastructure will thus likely pay recurring public health benefits for years. 6/6
