This film feels a little confused, and doesn't really make good use of a potentially enthralling world of diversity in the affected.
The main story focusses on illness of Spike's mother, and his desire to heal her with a known doctor. This takes a particularly dark and unnecessary turn , leaving you feeling the whole thing was ridiculous and weird.
I feel opportunities were missed in terms of the Alpha, if the first one had killed Spike's father on the bridge and then avenged by him, than that surely would have made a compelling hook. Potentially pushing the mother's illness a secondary story.
Naming the next one should be interesting as were 28 days after 28 years from 28 weeks and 28 days later or more at this point...