It's not a minor difference. My understanding is that the text is referring to the impact of economic "activity," which is expressed in the singular.

42,000 hits for "the health care activity" - examples:

Mar 12, 2010 ... “The complexity of the health care activity coupled with the number of individuals involved with an activity influences the probability of ...
ahier.blogspot.com/2010/03/patient-safety-and-patient-centered.html

... the cost of each component and the cost of the health care activity can be calculated. Health care differs from other industries in many ways. ...
books.google.com/books?isbn=083421010X...

entrepreneurs engaged in the health care activity and retail trade of pharmaceutical goods (with regard to financial results of activity), as well ...
www.armstat.am/file/article/aroxjap_kazm-het-ang-iii.9..pdf

... it does not affect the prices and costs of other goods and services. If the health care activity is on a small scale, the tax revenues ...
books.google.com/books?isbn=184376508X...