Does negative effectiveness mean that actually you are more likely to catch COVID if you had a Moderna shot than without it? I wonder whether the issue is with Moderna or mRNA vaccines in general - they failed hard in previous non-COVID outbreaks, maybe the same is happenning now?Besides the fact that China's own Walvax mRNA vaccine has been approved for emergency use in Indonesia, there is one more reason that China should not bother with the Moderna vaccine anymore: a new study indicates that their effectiveness turns negative after 150 days.