I mixed up two big insurance companies -- and lots of readers -- in Friday's report about a new Health, Education and Welfare brochure. The guide was designed to help federal workers (and retirees) pick the best 1980 health insurance deal at the lowest cost. It will be available soon at agency personnel offices, in time for people to study it during the Nov. 17 to Dec. 7 open season period when they can switch plans.

HEW is encouraging workers to consider enrolling in HMOs (Health Maintenance Organizations) if that sort of coverage suits them. There are four local HMOs in the federal insurance program. They are: George Washington HMO, Georgetown University HMO; Group Health Association and Health-Plus HMO. The two major insurance plans are Blue Cross-Blue Shield and Aetna.

New 1980 premium rates for Blue Cross-Blue Shield, for high option, family coverage will be $26.87. Aetna will charge $12.56. The George Washington HMO plan will cost $28.75; Georgetown's HMO, $31.75; Group Health, $36.75 and Health-Plus rates will be $35.22 for high option, family coverage.

My mistake came in transposing the names of Blue Cross-Blue Shield and Aetna in listing benefits paid for in-patient hospital care. This is what they are: Blue Cross-Blue Shield pays 100 percent for up to 365 days, then 80 percent thereafter. Aetna pays 100 percent of the first $2,000 in costs, then 80 percent thereafter.

If your personnel office is slow in getting the HEW comparison brochure, you can call HEW's Office of Health Maintenance Organizations next week on 443-2300.