Emergence of SARS-CoV-2 Omicron lineages BA.4 and BA.5 in South Africa

Houriiyah Tegally, Monika Moir, Josie Everatt, Marta Giovanetti, Cathrine Scheepers, Eduan Wilkinson, Kathleen Subramoney, Zinhle Makatini, Sikhulile Moyo, Daniel G. Amoako, Cheryl Baxter, Christian L. Althaus, Ugochukwu J. Anyaneji, Dikeledi Kekana, Raquel Viana, Jennifer Giandhari, Richard J. Lessells, Tongai Maponga, Dorcas Maruapula, Wonderful ChogaMogomotsi Matshaba, Mpaphi B. Mbulawa, Nokukhanya Msomi, Yeshnee Naidoo, Sureshnee Pillay, Tomasz Janusz Sanko, James E. San, Lesley Scott, Lavanya Singh, Nonkululeko A. Magini, Pamela Smith-Lawrence, Wendy Stevens, Graeme Dor, Derek Tshiabuila, Nicole Wolter, Wolfgang Preiser, Florette K. Treurnicht, Marietjie Venter, Georginah Chiloane, Caitlyn Mcintyre, Aine O’toole, Christopher Ruis, Thomas P. Peacock, Cornelius Roemer, Sergei L. Kosakovsky Pond, Carolyn Williamson, Oliver G. Pybus, Jinal N. Bhiman, Allison Glass, Darren P. Martin, Ben Jackson, Andrew Rambaut, Oluwakemi Laguda-Akingba, Simani Gaseitsiwe, Anne Von Gottberg, Tulio De Oliveira

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Three lineages (BA.1, BA.2 and BA.3) of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant of concern predominantly drove South Africa’s fourth Coronavirus Disease 2019 (COVID-19) wave. We have now identified two new lineages, BA.4 and BA.5, responsible for a fifth wave of infections. The spike proteins of BA.4 and BA.5 are identical, and similar to BA.2 except for the addition of 69–70 deletion (present in the Alpha variant and the BA.1 lineage), L452R (present in the Delta variant), F486V and the wild-type amino acid at Q493. The two lineages differ only outside of the spike region. The 69–70 deletion in spike allows these lineages to be identified by the proxy marker of S-gene target failure, on the background of variants not possessing this feature. BA.4 and BA.5 have rapidly replaced BA.2, reaching more than 50% of sequenced cases in South Africa by the first week of April 2022. Using a multinomial logistic regression model, we estimated growth advantages for BA.4 and BA.5 of 0.08 (95% confidence interval (CI): 0.08–0.09) and 0.10 (95% CI: 0.09–0.11) per day, respectively, over BA.2 in South Africa. The continued discovery of genetically diverse Omicron lineages points to the hypothesis that a discrete reservoir, such as human chronic infections and/or animal hosts, is potentially contributing to further evolution and dispersal of the virus.
Original languageEnglish
Pages (from-to)1785-1790
Number of pages18
JournalNature Medicine
Issue number9
Early online date27 Jun 2022
Publication statusPublished - 1 Sept 2022

Keywords / Materials (for Non-textual outputs)

  • Amino Acids
  • Animals
  • COVID-19/epidemiology
  • Humans
  • SARS-CoV-2/genetics
  • South Africa/epidemiology
  • Spike Glycoprotein, Coronavirus/genetics


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