A seroepidemiological study of measles: Some practical implications for measles immunization program, Kingdom of Saudi Arabia.

It was hypothesized that the recent outbreaks of measles in a geographically defined area of Al-Qassim might reflect significant changes in the epidemiology of measles and cast doubt upon the real protective value of measles vaccines. Therefore, the two objectives of this research were to study some epidemiological parameters of cases of measles (n=993) and the current immunological status of immunized children (n=2810). The crossmatched data about measles patients were collected on an official proforma and 3 mL of blood were extracted from each child for determining the measles IgG and IgM antibodies. The results showed that female patients were significantly overrepresented (51.3%). The majority of patients encountered at primary health care centers (PHCCs) (81.3%) were more than five years of age (76.5%). Among nonvaccinated measles cases, 54.9% (n=402) were from rural/desert areas. The measles vaccine failure rate was 26.3%. The results of the surveyed children showed that 2% of them were not vaccinated. The measles IgM levels were detected significantly in recently vaccinated females (n=29/51, 56.9%). The measles IgG positivity unaffected by age, sex, and residence was found in 87.4% of children. A significant portion of children from rural/desert areas were not vaccinated (n=44/57, 77.2%). Though there were apparently high seroconversion rates in children under two years of age following Edmonston-Zagreb vaccine, overall it did not achieve any statistical significance when compared with seroconversion rates in all children following Schwartz vaccine. We conclude that besides at age six months, and MMR containing measles vaccine at 12 months, children at school entry (six years) should also be considered for measles vaccination.