Potential Causes of Increased Transmission in COVID-19 Variants

Patients with B.1.1.7 (Alpha variant/UK) and B.1.351 (Beta variant/South Africa) are less likely to be asymptomatic, despite no increase in viral load.

Although two SARS-CoV-2 variants are associated with higher transmission, patients with these variants show no evidence of higher viral loads in their upper respiratory tract compared to controls, according to a study from the Johns Hopkins School of Medicine.

The emergence and higher transmission of the evolving variants of SARS-CoV-2, the virus that causes COVID-19, is worrying. The researchers examined B.1.1.7, the variant first identified in the UK, and B.1.351, the variant first identified in South Africa, to evaluate whether patients showed higher viral loads and consequently increased excretion and transmissibility.

Variants were identified using whole genome sequencing. Researchers used a large number of samples to show that the British variant made up 75% of circulating viruses by April 2021. The researchers compared 134 variant samples with 126 control samples and with access to the patients’ clinical information, they were able to correlate the genomics data with clinical disease and outcomes. All samples underwent additional testing to determine their viral load. The information was correlated with the stage of the disease by looking at the days after the onset of symptoms, which provided clarity when comparing viral shedding between groups.

“The reason why these variants show higher transferability is not yet clear,” said Adannaya Amadi, lead author of the study. “However, our findings showed that the patients infected with these variants were less likely to be asymptomatic compared to the control group. Although those infected with the variants were not at a higher risk of death or admission to intensive care, they had more chance of being hospitalized.”

This study was conducted in the research lab of Dr. Heba Mostafa at the Johns Hopkins School of Medicine, which has conducted large-scale whole-genome sequencing of SARS-CoV-2 for the state of Maryland and contributed data to the national publicly available surveillance figures.

Alex Luo, C. Paul Morris, Matthew Schwartz, Eili Y. Klein and Heba H. Mostafa also contributed to this work. The study was funded by NIH, the Johns Hopkins Department of Pathology, The Johns Hopkins University and the Maryland Department of Health.

This summary will be presented online June 20-24 at the World Microbe Forum, live from Baltimore, Maryland. World Microbe Forum is a collaboration between the American Society for Microbiology (ASM), the Federation of European Microbiological Societies (FEMS), and several other societies, breaking down barriers to science sharing and addressing the most pressing challenges facing humanity today. faced.