Thread: we've released results (pre-print) of an analysis examining #SARS_CoV_2 variants in #Ireland from hospital cases during 2020. This is the largest analysis of its kind to date in Ireland and provides some important insights into #COVID19Ireland. 1/9 https://www.medrxiv.org/content/10.1101/2021.02.09.21251402v1

The #COVID19 pandemic in Ireland was notable because we 'crushed' wave 1 (W1) with an effective lockdown and ended up with <5 daily new cases reported by June 2020. After that cases stayed flat until September when cases and hospitalisations rose again (image: @hpscireland) 2/9

We analysed 225 sequences from 4 hospitals in sth east Ireland from March to December 2020 (approx 15% admissions), across waves 1 and 2 of the #COVID19 pandemic. We detected several different variants in W1 but these disappeared with lockdown and didn't re-emerge during W2. 3/9

The main #SARS_CoV_2 variant detected in W2 was the B.1.177 variant. This was detected across Europe in Summer 2020, thought to have been distributed through travel. There was little evidence of persistence of W1 variants into W2 in #COVID19Ireland. https://www.medrxiv.org/content/10.1101/2020.10.25.20219063v2 4/9

In addition, when we analysed the B.1.177 sequences from W2, they more closely linked to sequences from outside Ireland than viruses from W1. This suggests multiple different introductions of B.1.177 variants into #Ireland, likely through travel, contributing to W2. #COVID19 5/9

What do these results suggest?
1. Effective lockdown leading to low transmission rates can essentially eliminate common #SARS_CoV_2 variants contributing to disease
..BUT..
2. ..new variants can be introduced (likely travel) that seed new waves of #COVID19 6/9

As daily infections fall, hopefully correct implementation of new travel restrictions can help stop future W4 of #COVID19Ireland. We also hope that this data helps people understand how travel contributes to new #COVID19 infections (and new variants) coming into the country. 7/9

This analysis is from the All Ireland Infectious Diseases (AIID) Cohort, coordinated by @CEPHR_UCD and @UCDMedicine in collaboration with the Irish Coronavirus Sequencing Consortium led by @pauldcotter, funded by @scienceirel. 8/9

Thanks to >1,200 people with #COVID19Ireland who continue to contribute time and valuable samples to help us learn more about #COVID19. Collaborative research (11 collaborating sites) and biobanks can provide invaluable insights to help us tackle #COVID19Ireland 9/8