Sir.—In March 1990 we published a study in AJDC1 indicating that adult hospital employees, with significant frequency, tested seronegative to measles. We identified 16 such workers whom we subsequently immunized with monovalent measles vaccine. We further recommended and initiated a screening program to test new employees for immunity to measles and to immunize those who tested seronegative.
Correspondents have suggested to us that these seronegative individuals might represent primary immunization failures, and, therefore, a significant number might not seroconvert following the administration of vaccine. Some expressed interest in follow-up data on this population.
Accordingly, we solicited and were able to obtain serum samples from 15 seronegative individuals and study them by the methods described in our article.1 Of these 15 employees who were subsequently vaccinated, 13 were members of the original group of 16 and two were employees identified in our ongoing screening program.
All 15 employees