It seems to affect only workers who commute from New Jersey. In addition, it doesn't affect anyone who takes public transportation or even those who drive into the city by themselves. Only those people who travel with others in the same automobile seem to suffer from it. Finally, after further analysis of the data, those who travel to NYC from NJ via the bridges or ferry system seem to be immune.
The CDC thinks it could be an outbreak of
Spoiler
Carpool Tunnel Syndrome.
