MEASLES ANTIBODY LEVELS AFTER VACCINATION WITH EDMONSTON-ZAGREB AND SCHWARZ MEASLES VACCINE AT 9 MONTHS OR AT 9 AND 18 MONTHS OF AGE: A SEROLOGICAL STUDY WITHIN A RANDOMISED TRIAL OF DIFFERENT MEASLES VACCINES

Tuesday, 23rd of September 2014

[source]Vaccine[|source]

It has recently been suggested to increase the age of vaccination in other regions when measles comes under control. An increase in age of primary measles vaccine (MV) could dramatically enlarge the number of susceptible infants in crowded urban areas, especially in Africa. Secondly, increasing the age of administration would limit the beneficial non-specific effects of MV. Thus finding the best schedule and vaccine strain for use in a routine two-dose schedule might be the best approach for the African region.

In this study, the authors conducted studies of both early (4½ and 9 months) and later (9 and 18 months of age) two-dose MV strategies. In this report, the authors present a comparison of the antibody response of standard-dose EZ and SW MV when administered at 9 and 18 months of age. The report concludes that it is unlikely that measles prevention and child health will be improved by increasing the age of MV. Detailed findings and recommendations are accessible at: http://www.sciencedirect.com/science/article/pii/S0264410X13011353

 

ABSTRACT

BACKGROUND: Standard–titre Schwarz (SW) and Edmonston-Zagreb (EZ) measles vaccines (MV) are both used in the routine immunisation programme. Within a trial of different strains of MV, we examined antibody responses in both one-dose and two-dose schedules when the first dose was administered at 9 months.

SETTING AND METHODS: The trial was conducted in an urban area in Guinea-Bissau where we have had a health and demographic surveillance system and studied strategies to prevent measles infection since 1978. In the present study, children were randomised to SW or EZ as the first MV and furthermore randomised to a second dose of the same MV or no vaccine at 18 months of age. We obtained blood samples from 996 children at baseline; post-vaccination blood samples were collected at 18 and 24 months of age to assess measles antibody levels after one or two doses of MV.

RESULTS: At age 18 months all had responded to the first dose and only 1% (8/699) of the children had non-protective antibody levels irrespective of vaccine type. SW was associated with significantly higher levels of measles antibodies (geometric mean titre (GMT) = 2114 mIU/mL (95%CI 1153–2412)) than EZ (GMT = 807 mIU/mL (722–908)) (p = 0.001). Antibody concentration was significantly higher in girls than in boys after EZ but not after SW. Antibody levels were higher in the rainy than the dry season. There was no clear indication that a booster dose at 18 months increased the antibody level at 24 months of age.

CONCLUSIONS: Maternal antibody levels have declined significantly in recent years and 99% had protective levels of measles antibody following primary MV at 9 months of age. It is unlikely that measles prevention and child health will be improved by increasing the age of MV as currently recommended.