Oysters are filter feeders and can filter up and then hold the viruses.
There have been even more cases of oyster related Norovirus infections in Canada. In BC, hundreds have become infected with Norovirus after eating oysters.
Interesting, while there appears to be no link between outbreaks in the US and Canada because the cases in Washington are said to be linked to oyster from Washington, not Canada. But in the article, it states that the Canadians are said to export much of their product to the US,....so, could it be that these Canadian oysters really the oysters that caused illness in the US, but these oysters were labeled as such to make them appear local and these are linked to the cases further north? Or did someone eat the Canadian oysters neat the US waters, have a bout of illness, thus contaminating the US oysters? Or...it is just a weird occurrence that two oyster-related Norovirus outbreaks are happening at the same time?
In any event, eating raw oysters has a Norovirus risk, no matter how tasty they are.
Q13 Fox News
http://q13fox.com/2017/03/28/raw-oyster-norovirus-warning-issued-after-multiple-people-in-area-become-ill/
Raw oysters, norovirus warning issued after multiple people in area become ill
Posted 5:04 PM, March 28, 2017, by Q13 FOX News Staff, Updated at 11:12PM, March 28, 2017