The evolution and emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have caused concern for increased transmissibility1, pathogenicity2, and altered effectiveness of diagnostics3, therapeutics, and vaccines4. Human-to-animal transmission of SARS-CoV-2 is well-documented in pets5, which typically become infected after exposure to owners with COVID-196. However, the impact of infections with SARS-CoV-2 variants of concern on the clinical presentation and duration of infection in pets and the transmissibility between people and pets remains unknown. Since June 2020, we have conducted a longitudinal household transmission study of pets living with one or more persons with COVID-197 to better understand the role of virus transmission between humans and pets.
As part of this ongoing study, two pets from the same household were sampled for SARS-CoV-2 on February 12, 2021, two days after their owner—one of two residents in a home in Brazos County, Texas—received a positive test result for COVID-19 through a commercial laboratory; no viral sequence was generated from the owner. The pets—the only animals in the home—were a 15-year-old Labrador retriever mix dog and a 12-year-old domestic shorthair cat. On initial visit, the animals were asymptomatic. The owner described a high degree of contact with both pets, including sleeping in the same room (dog) and bed (cat). Following previously described methods7, oral, nasal, and fur swabs from both pets were found to be positive for SARS-CoV-2 by real-time (RT) PCR. Rectal swabs tested negative. Sera tested negative for SARS-CoV-2 neutralizing antibodies (Table). Live virus isolation was attempted from all positive samples and was successful from the cat’s nasal swab. SARS-CoV-2 whole genome sequencing was attempted and successful from the cat’s nasal swab and the dog’s oral swab. Consensus sequences from both animals were 100% identical to each other and were identified as the B.1.1.7 variant of concern by single-nucleotide polymorphism (SNP) analysis and alignment. In addition to characteristic B.1.1.7 mutations, sequences from both animals also showed 8 SNPs in ORF1ab and ORF8.
These pets were resampled on March 11, at which time the owner disclosed both had been sneezing over the past weeks. Pets were resampled again on March 15, and clinical signs had resolved. Nasal and rectal swabs from both resample time points tested negative, while fur swabs (both animals) and the oral swab (dog) remained positive with high Ct. Neutralizing antibodies were detected in both animals (Table).
This study documents the first detection of B.1.1.7. in companion animals in the United States, and the first genome recovery and isolation of B.1.1.7 variant of concern globally in any animal. These findings are coincident with detection of B.1.1.7 infection in rectal swabs of three U.K. pets with myocarditis8. These results support public health guidance that recommends people with COVID-19 isolate from animals9 and the continued application of a One Health approach to SARS-CoV-2 investigations. Given the continued emergence10 and enhanced transmissibility and pathogenicity of B.1.1.7 in humans1, onward transmission of this and other variants of concern from animals should remain the subject of ongoing research.