Air travel-related outbreak of multiple SARS-CoV-2 variants (preprint)

Background. A large cluster of 59 cases were linked to a single flight with 146 passengers from New Delhi to Hong Kong in April 2021. This outbreak coincided with early reports of exponential pandemic growth in New Delhi, which reached a peak of >400,000 newly confirmed cases on 7 May 2021. Methods. Epidemiological information including date of symptom onset, date of positive-sample detection, and travel and contact history for individual cases from this flight were collected. Whole genome sequencing was performed, and sequences were classified based on the dynamic Pango nomenclature system. Maximum-likelihood phylogenetic analysis compared sequences from this flight alongside other cases imported from India to Hong Kong on 26 flights between June 2020 and April 2021, as well as sequences from India or associated with India-related travel from February to April 2021, and 1,217 reference sequences. Results. Sequence analysis identified six lineages of SARS-CoV-2 belonging to two variants of concern (Alpha and Delta) and one variant of public health interest (Kappa) involved in this outbreak. Phylogenetic analysis confirmed at least three independent sub-lineages of Alpha with limited onward transmission, a superspreading event comprising 37 cases of Kappa, and transmission of Delta to only one passenger. Additional analysis of another 26 flights from India to Hong Kong confirmed widespread circulation of all three variants in India since early March 2021. Conclusions. The broad spectrum of disease severity and long incubation period of SARS-CoV-2 pose a challenge for surveillance and control. As illustrated by this particular outbreak, opportunistic infections of SARS-CoV-2 can occur irrespective of variant lineage, and requiring a nucleic acid test within 72 hours of departure may be insufficient to prevent importation or in-flight transmission.

SARS-CoV-2 virus culture from the upper respiratory tract: Correlation with viral load, subgenomic viral RNA and duration of illness. (preprint)

In 68 respiratory specimens from a cohort of 35 COVID-19 patients, 32 of them with mild disease, we found SARS coronavirus-2 virus culture and sub-genomic RNA was rarely detectable beyond 8 days after onset of illness although virus RNA by RT-PCR remained detectable for many weeks.

Canine SARS-CoV-2 infection (preprint)

SARS-CoV-2 emerged in Wuhan in December 2019 and has caused the pandemic respiratory disease, COVID-19. Following what is presumed to be an initial zoonotic transmission event, the virus is now spreading efficient in humans. Very little is known about the susceptibility of domestic mammals kept as pets to this virus. Samples were collected over a 13-day period from a 17 year-old neutered male Pomeranian in Hong Kong SA that was taken into isolation after two members of the household tested positive for the virus. Nasal swabs were consistently positive on the five occasions the dog was tested using quantitative RT- PCR with viral loads between 7.5xE2 to 2.6 x10E4 RNA copies per mL of sample. The dog remained asymptomatic. Cultures attempted on three RT-PCR positive nasal samples were negative. Gene sequences from samples from two household members were identical. The viral sequence from the dog differed at three nucleotide positions; two of these resulted in amino acid changes but their significance is yet to be determined. Seroconversion was not detected but this was expected given the asymptomatic infection and low virus load. The evidence suggests that this is an instance of human-to-animal transmission of SARS-COV-2. It is likely that we could see similar events in other infected households. We do not have information yet on whether this virus can cause illness in dogs but no specific signs were seen in this dog. Whether infected dogs could transmit the virus to other animals or back to humans remains unknown. In this case it did not appear to have occurred.