Thread by @nextstrain

Thanks to fast sequencing & #opendata sharing from Institute of Viral Disease Control & Prevention, China CDC & @GISAID, 3 sequences from the recent #SARSCoV2 #COVID19 Beijing outbreak are now on nextstrain.org/ncov

They fall in clade 20B - frequently observed in Europe

1/6

@GISAID In our global build, the nearest sequences are from the Czech Republic, Taiwan, Greece & Portugal.

However, it's important to remember our builds are downsampled. We can look at the regional builds for different perspectives.

2/6

@GISAID In the Asian build (left) we see same Czech & Taiwan seqs, but also nearby seqs from Denmark, Columbia, Israel, Austria.

In the Europe build (right), we see the Czech & Denmark seqs, but many other sequences from Europe. Some (Portugal, Sweden) are only 1 mutation away

3/6

@GISAID This indicates the Beijing outbreak:
- Is part of existing #SARSCoV2 #COVID19 diversity - not a new jump from animals
- Is related to viruses circulating in Europe
- Is similar to sequences from many countries - we cannot say exactly where it may have originated

4/6

@GISAID Additionally, we can see there is some diversity in these sequences - they are not identical. This may indicate unobserved circulation occurring before these samples were taken.

5/6

@GISAID It's important to keep in mind that our inferences are limited: we cannot say exactly when the virus came to Beijing or from what country.

However, having these sequences - 2 from people & 1 environmental - is incredibly helpful to our understanding of the Beijing outbreak!

6/6