Whilst the kernels look to have been patched properly afaict (using the backported 4.9 kernel in Jessie), Debian doesn't make it clear if they will rebuild the whole archive yet.
https://wiki.debian.org/DebianSecurity/SpectreMeltdown
"No archive rebuild is planned at this point .."
I'm no expert in this, but it would seem better to me if they did rebuild.
Thanks,
chillfan