Subclinical measles infection in vaccinated seropositive individuals in arctic Greenland.

Measles vaccination was performed in the arctic district of Scoresbysund, Greenland in 1968, which had never been exposed to natural measles. More than 90% of the total population was vaccinated and a 94-100% seroconversion was obtained. During a serological survey to examine the immunity status of the vaccinees, it was discovered that a temporary increase in measles antibodies took place in the majority of the population 2-4 years after the vaccination. This was not accompanied by clinically observed measles. Most likely, it was due to an inapparent measles infection in a population considered highly immune after vaccination.

Long-term antibody response after measles vaccination in an isolated arctic society in Greenland.

Scoresbysund is an isolated district on the east coast of Greenland with 500 inhabitants, mainly Polar Eskimos, which had never been exposed to natural measles. In 1968 more than 90% of the population were vaccinated with the Schwarz live further-attenuated measles vaccine and subsequently children born after 1968 likewise received the measles vaccination. Upon the initial measles vaccination no clinical cases of measles have been observed. The immunity status of the isolated population has been followed for 16 years after vaccination by IgM, IgA, and IgG ELISA tests and by HI test on a series of serum samples taken at intervals. Immunoblotting was performed on sera obtained 16 years after the vaccination. In general, antibody studies have demonstrated some decline in antibody titres after the initial measles vaccination. However, a temporary moderate increase in measles antibodies occurred in some individuals 2-4 years after vaccination, probably due to a reinfection of vaccinees. Most of these individuals did not have demonstrable IgA antibodies prior to the supposed reinfection.

Vaccination with inactivated poliovirus vaccine and oral poliovirus vaccine in Denmark.

In Denmark a polio vaccination program including both inactivated poliovirus vaccine (IPV) and oral poliovirus vaccine ( OPV ) has been in use since 1968. Three injections of IPV are given when the children are five, six, and 15 months of age. Subsequently, three vaccinations with trivalent OPV are administered at the age of three, four, and five years. The acceptance rate is high-93%-98%-and greater than 95% of the population has antibodies to poliovirus. The geometric mean titer of serum antibodies is much greater than 10 IU for all three types. The epidemiology of poliomyelitis and the background for the development of the present vaccination schedule are reviewed.

WHO collaborative study on the sero-epidemiology of rubella.

Under the auspices of WHO an investigation was made by 9 laboratories in different parts of the world on the distribution of rubella antibodies in girls and women of child-bearing age. In the first part of the study the objective was to determine the reliability and reproducibility of the tests employed. It was found that there were no significant differences in the variability of the titres obtained in different laboratories when the results were compared with those obtained by repeatedly testing the same sera in one laboratory.In the second part of the study sera were obtained from girls in schools and women attending clinics and health centres. They were not taken from random samples of the populations. In most of the studies the pattern of development of antibody was similar. About half the persons had antibody at 6-8 years of age and 80%-87% at 17-22 years of age, the percentage remaining relatively constant thereafter. The island populations of Trinidad and Jamaica and a rural area of Japan were, however, found to have significantly fewer women with antibodies than urban areas in Europe or the Americas.