COVID variants exploited air travel for swift spread

Nations with large volumes of outgoing air traffic accounted for a high proportion of variant exports.

Delta and other variants of SARS-CoV-2 (viral particles, artificially coloured) have spread across the globe in part by hitching rides on aeroplanes. Credit: Eye Of Science/SPL

Air travel during the COVID-19 pandemic contributed significantly to the spread of SARS-CoV-2 variants1.

Houriiyah Tegally at CERI Stellenbosch University in South Africa and her colleagues analysed hundreds of thousands of genomes from viral samples collected in more than 100 countries and belonging to six SARS-CoV-2 variants. They found that the United States was the largest exporter of variants to other countries, contributing about 30% of all variant exports, followed by India, the United Kingdom, South Africa and Germany. Overall, countries with a larger volume of outgoing air passengers accounted for a greater proportion of variant exports than did countries with fewer outgoing travellers.

The authors also found that the countries presumed to be the origins of variants that emerged earlier in the pandemic played a larger part in the virus’s spread than the nations thought to be the origins of Delta and Omicron, which emerged later. Travel bans put in place in the latter part of the pandemic, after earlier restrictions on global travel had already been lifted, did very little to stop the Omicron variant’s spread.

Download PDF - Nature 619, 225 (2023), doi: .


- Tegally, H. et al. Cell (2023).

News date: 2023-07-06


Publication cited

Dispersal patterns and influence of air travel during the global expansion of SARS-CoV-2 variants of concern. Tegally H, Wilkinson E, Tsui JL, Moir M, Martin D, Brito AF, Giovanetti M, Khan K, Huber C, Bogoch II, San JE, Poongavanan J, Xavier JS, Candido DDS, Romero F, Baxter C, Pybus OG, Lessells RJ, Faria NR, Kraemer MUG, de Oliveira T, Cell (2023), S0092-8674(23)00641-4. doi: 10.1016/j.cell.2023.06.001:.

KRISP has been created by the coordinated effort of the University of KwaZulu-Natal (UKZN), the Technology Innovation Agency (TIA) and the South African Medical Research Countil (SAMRC).

Location: K-RITH Tower Building
Nelson R Mandela School of Medicine, UKZN
719 Umbilo Road, Durban, South Africa.
Director: Prof. Tulio de Oliveira