Thanks to Greg Folkers for sending the link to this report in The Journal of Infectious Diseases: Investigation of anti-MERS-Coronavirus antibodies in blood donors and abattoir workers in Jeddah and Makkah, Kingdom of Saudi Arabia, fall 2012. The abstract:
Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a novel, potentially zoonotic human coronavirus (HCoV). We investigated MERS-CoV antibodies using a staged approach involving immunofluorescence assay (IFA), differential recombinant IFA, and plaque reduction serum neutralization assay.
In 130 blood donors sampled during 2012 in Jeddah, and 226 abattoir workers sampled in October 2012 in Jeddah and Makkah, 8 reactive sera were seen in IFA but were resolved to be specific for established HCoVs by discriminative testing.
There is no evidence MERS-CoV circulated widely in the study region in fall 2012, matching an apparent absence of exported disease during the 2012 Hajj.