All issues > Volume 34(9); 1991

Original Article

J Korean Pediatr Soc. 1991;34(9):1201-1210. Published online September 30, 1991.

Serological study to determine the optimum age for measles vaccination in Korea.

Gum Ja Lee¹, Kon Hee Lee¹, Hae Sun Yoon¹

¹Department of Pediatrics, College of Medicine, Hallym University, Seoul, Korea

Received: March 29, 1991;  Accepted: June 12, 1991.

Abstract

In recent years, measles outbreak has involved a great population of cases in younger children. For this reason, we reevaluated the conventional vaccination schedule by measuring measles antibody level. Two groups totalling 244 children were included in the study. The non-measles group consisted of 133 children who visited or were admitted to our hospital during the 7 month period from Jan. 1990 through July 1990 and had no history of infection with measles or exposure to it. The measles antibody titers were assessed by the Hemagglutinaton inhibition test. To detect the trends in persisting maternal antibody titers, measles titers were measured from 49 infants before measles vaccination. To assess the effect of measles vaccination at 9 months, 15 months and 9 & 15 months, we collected sera after vaccination. The measles group, which consisted of 111 patients who were clinically diagnosed as having measles during the 12 month period between Aug. 1989 and July 1990, were investigated with respect to the age of onset, monthly distribution and vaccination history. The results were as follows: 1) Of the measles group, 39 (35.1%) had vaccination during the first 9 or 15 months of their age while 72 (64.9%) did not, historically. 2) The peak incidence of the disease among the measles group was 15 months through 5 years for the vaccinated patient and 6 through 15 months of age for the non-vaccinated patient. 3) In the non-measles group, the antibody level (maternal origin) of those not vaccinated remainded at the optimal level (over 1:8 HI titer) until 5 months of age, but reduced in tendency as the infant* s age reached 6 months or older. 4) Of the 35 of the non-measles group vaccinated at the age of 9 months and the 13 of non-measles group vaccinated at the age of 15 months, 2 (5.7%) and 4 (30.7%) had the antibody level of below 1: 8 titer. Two (5.7%) of the 35 non-measles group patients who were vaccinated at the age of 9 and 15 months showed the antibody level below 1:8 titer，while the remainder had continued at a high level. 5) The vaccinated non-measles group patients showed no difference by sex, residence and place of vaccination as far as attaining optimal antibody level (over 1:8 titer) was concerned. 6) Four (20.0%) of the 20 non-measles group who were vaccinated at the age of 9 or 15 months and 2 years of age or older, showed the antibody level to be below 1:8 titer Conclusively, the optimal level of passive measles antibody continued until the first 5 months of age in infants who had not been vaccinated among the non-measles group, and began to decline to the level below 1:8 titer. On the other hand, measles cases were detected from 5 months of age, such cases reaching their peak between the age of 6 to 15 months. Therefore about 6 months of age may be suggested as the optimum age for initial measles vaccination.

Keywords :Measles;Hemagglutination lnhibition titer;Vaccination;Maternal antibody of Uninfected and Unvaccinated lnfants