Elimination of maternal antibodies against measles (is the policy of vaccinating children younger than nine months of age suitable for Turkey?).

Maternal antibodies against measles in 223 healthy children aged 22 to 31 weeks were studied. The ratio of children with detectable antibodies declined from 61.4 percent at 22-23 weeks of age to 20 percent at 26-27 weeks of age. Since the minimum proportion of antibody-positive children (15.6% at 26-27 weeks of age) is still higher than the optimum proportion (5%), the Schwarz vaccine which is used mostly in measles immunization seems not to be effective to obtain a high seroconversion rate in our infants. We suggest that the Edmonston-Zagreb strain of measles vaccine be used for infants under 9 months of age in Turkey.     

Passive immunity to measles in the breastmilk and cord blood of some nigerian subjects

Maternal and cord blood collected from 33 Nigerian mother-child pairs were tested for measles-sepcific IgG. All 33 had protective measles antibodies at the time of delivery with a positive correlation of r = 0.87. Determination of the rate of waning of these antibodies revealed that 58 per cent of these children had lost the protective maternal antibody by the age of 4 months and only 3 per cent of the children had enough antibody to protect them between the ages of 6-9 months. Fifty-five colostrum samples from the same mothers and 347 breastmilk samples collected at various periods of breastfeeding also showed that anti-measles IgA had dropped below the protective cut-off within the first 2 weeks of birth. It is evident that the Nigerian child is born with solid anti-measles antibody but the rate of waning has left a large number unprotected before the first dose of the vaccine. There is an urgent need to review the measles vaccination programme in Nigeria to protect these susceptible infants.     

Reimmunization following early immunization with measles vaccine: a prospective study

A prospective study was designed to determine the response of previously immunized infants following administration of measles vaccine at 15 to 18 months of age. Upon entry into the study at 7 to 12 months of age, 14 of 127 infants had measles antibody. Measles vaccine was administered to infants in the experimental group on the day of entry into the study. Prior to measles, mumps, and rubella vaccine administration at 15 to 18 months of age, six of 23 infants in the control group and 80 of 90 infants in the experimental group had detectable antibodies. Following the (re)vaccination at 15 to 18 months of age, 20 of 21 infants in the control group and 49 of 52 infants in the experimental group had detectable antibody. Early measles immunization in this study did not interfere with the ultimate response to immunization at 15 to 18 months of age. These results support the policy of early immunization for those infants at risk for exposure to measles and reimmunization at 15 months of age.     

Enhancement in seroconversion to measles vaccine with simultaneous administration of vitamin A in 9-months-old Indian infants

The mutual interactions of measles vaccine and vitamin A dose when administered simultaneously to 9 month old infants are explored in this study. One hundred healthy infants of 9 months of age received EZ strain of measles vaccine in the routine immunization clinic along with either 100,000 IU of vitamin A or a placebo orally. Blood samples were collected before and 4 weeks after intervention. They were coded and analysed for serum retinol and Hemagglutination Inhibition (HI) antibodies to measles. Ninety five per cent of the infants were seronegative to measles prior to vaccination with a seroconversion rate of 63% in the control group and a significantly higher percent of 83.7% in the experimental group (P < 0.01). Seroconversion was not related to initial serum retinol levels in either of the groups. 42% of infants had serum retinol levels less than 20 ug/dl before administration of the vaccine and both the groups showed improvement in vitamin A status following intervention, the increase being significant in the experimental group (from 22.4 ± 1.32 to 26.0 ± 1.07; P < 0.05). The results indicate that majority of the infants at 9 months of age were seronegative to measles. Seroconversion to measles vaccine in the routine immunization clinics was low. Simultaneous administration of vitamin A and measles vaccine had beneficial effects on vitamin A status as well as seroconversion rates to the vaccine in 9 months old infants.     

Serological response to early measles vaccination

This study compares the persistence of measles IgG antibody in 239 children vaccinated at 6-8 months of age with 76 children vaccinated after 8 months of age. Among the children vaccinated prior to 9 months, 49 per cent of the children between 16 and 44 months and 33 per cent of children over 54 months had levels of measles IgG antibody conventionally considered protective. Among the children older than 48 months, 67 per cent of children vaccinated before 9 months and 13 per cent of children vaccinated after 8 months had antibody levels below the conventionally accepted protective levels of 0.2 IU/ml. Older children had lower antibody levels than younger children. Measles immunization before 9 months with the standard titer Edmonston-Zagreb vaccine has not provided a large proportion of under-five children with protective levels of measles IgG antibody. A significant proportion of children vaccinated at the currently recommended age also had suboptimal levels. It is difficult to protect the majority of the measles-susceptible population with a single dose regardless of the immunization schedule used. A second dose of measles vaccine may be necessary to increase the herd immunity.     

Seroconversion after measles vaccination at nine and fifteen months of age

BACKGROUND: Despite high vaccination coverage, single dose measles immunization programs have been unsuccessful in eliminating the disease. Because seroconversion rates are lower in infants vaccinated before 12 months of age, a second dose of measles vaccine is recommended at 15 months. The aim of this study was to determine the seroconversion rates in children after the first and second doses of measles vaccinations at 9 and 15 months of age. METHODS: Study population comprised 116 infants attending the Well Baby Clinic of Istanbul University, Faculty of Medicine. Serum specimens were obtained from children before and 1 month after the first measles (Rouvax, Schwarz strain 1000 TCID(50)) vaccine given at 9 months. A second dose was given to 72 children at 15 months of age as measles-mumps-rubella (Trimovax, Schwarz measles strain, 1000 TCID(50); Urabe Am 9 mumps strain, 5000 TCID(50); Wister RA 27/3 rubella strain, 1000 TCID(50)). Third blood samples were collected 20 months after the second vaccine. RESULTS: Passive antibody positivity rate was 5.2% at the age of 9 months. Seroconversion rate was 77.6% after the first dose and 81.9% after the second dose of measles vaccine. Of 15 children who were seronegative, 13 (86.7%) became seropositive after the immunization at 15 months. Eleven children (19.2%) seroconverted from positive to negative after the second vaccine. CONCLUSION: The two dose schedule seems to increase the seropositivity rate. Our findings also indicate that increasing vaccination coverage and revaccination at 6 years of age are important even with the early two dose schedule.     

Measles seroprevalence in Izmir with special emphasis on measles vaccination policy for Turkey

BACKGROUND: Measles outbreaks seem to occur every 2- to 3-year intervals in Turkey. However, sero-epidemiological studies are limited. Knowing the prevalence of measles susceptibility as measured either by serologic markers of immunity or surveys of vaccination coverage is an important tool to assess the risk for measles outbreaks. METHODS: In order to determine the seroprevalence of measles antibodies among a 1 to 29-year-old population in Izmir (Turkey) and to develop the best vaccination policy for measles, a total of 600 people aged from 1 to 29 were selected for the study with cluster sampling. The information on sociodemographic characteristics, vaccination status and measles history was gathered for each participant. Measles-specific IgG antibodies were screened qualitatively by using microenzyme immune assay for 595 subjects. RESULTS: Of the 595 participants screened for the measles antibodies, 56 (9.4%) were seronegative. The proportion of the susceptible individuals in the age groups of 1-4, 5-9, 10-14, 15-19 and 20-29 was 20.0, 10.4, 6.0, 10.3 and 3.0%, respectively. The logistic regression analysis showed that none of the independent characteristics (sex, socioeconomic status, past measles history, vaccination status) with the exception of age group, was significantly associated with measles seronegativity. CONCLUSION: The optimal measles vaccination policy for Turkey may be to increase vaccination coverage above 90%, to conduct a catch-up campaign covering persons aged 1-19, regardless of previous vaccination status. Another factor to consider is to adopt a routine two-dose vaccination, giving the first dose at 12-15 months of age and the second dose at school entry.     

Evidence for reinstatement of infants 12 to 14 months of age into routine measles immunization programs

The hemagglutination inhibition (HI) serologic responses of 851 measles-susceptible infants and children to the live, further-attenuated measles virus vaccine were evaluated over a ten-year period. The response by age at 23-day intervals was determined. Infants inoculated at 12 through 14 months of age demonstrated seroconversion rates by HI assay comparable to those in infants and children inoculated at 15 months of age or older. This finding does not support the recent recommendation that routine active immunization with measles vaccine should be postponed until 15 months of age. We emphasize the possible consequence of electively leaving infants 12 throught 14 months of age vulnerable to measles because of the current endemicity of this disease in the United States. We also present evidence for the reinstatement of infants 12 through 14 months of age into routine measles immunization programs and for the need to further evaluate the causes for vaccine failure in vaccines after the loss of maternal antibody.     

Moderate immunization coverage levels in East Delhi: implications for disease control programmes and introduction of new vaccines

A vaccination coverage survey conducted in East Delhi in September 1999 showed that only 58.6 per cent of the children aged 12-23 months had received the full course of the vaccines recommended under the national immunization programme. Coverage with the third dose of DTP and oral polio vaccines was around 71 per cent, and with BCG and measles vaccines was 83 and 59 per cent, respectively. Drop-out rates between DTP1 and DTP3 and between DTP1 and measles immunization were 13.8 and 28.7 per cent, respectively. Nine per cent of the children had not received a single dose of any vaccine. The main reason for failure to immunize was lack of information. There was a marginal increase in DTP3 and OPV3 immunization coverage levels as recorded through a previous survey in 1996, a drop in coverage with measles vaccine from 64.3 to 59 per cent, and a significant increase in tetanus toxoid immunization coverage of pregnant women from 79.4 to 93 per cent. The percentage of children who had not received any vaccine declined from 13 to 9 per cent in the period between the two surveys. Coverage with hepatitis B vaccine at 14 per cent was only marginally higher than the baseline rate of 9 per cent before the vaccine was made available, free of cost, through government and municipal corporation health facilities.     

Clinical trial to evaluate immunogenicity and safety of inactivated hepatitis A vaccination starting at 2-month-old children

Active immunization with hepatitis A vaccine has been shown to provide long-term protection against hepatitis A virus (HAV) infection. However, few data are available regarding use of the hepatitis A vaccine in children under two years of age. The present study was conducted to test the safety and immunogenicity of inactivated hepatitis A vaccine administered to infants, and to evaluate the correlation between mother and infant anti-HAV antibodies. A total of sixty healthy children, two months of age, were enrolled in this study and immunized with 360 EU of inactivated hepatitis A vaccine (Havrix) according to the two, four and six months of age schedule. Blood sampling was performed prior to the first vaccination and one month after the third vaccination at seven months. Venipuncture was also done on mother on admission. The reactogenicity was expressed as the percentage of reported local and systemic reactions. The most common side effects were erythema on the injection site and fever. Infants with passively transferred maternal anti-HAV antibodies had a reduced anti-HAV GMT after vaccination. On admission, only one infant and his mother were seronegative and seroconversion was only detected in this infant. One month after the third dose seven infants (12.3%) were found to be seronegative. The infant without passively acquired maternal anti-HAV had the protective levels with a GMT of 3176 mIU/ml one month following the third dose. There was a significant positive correlation between the titers of mother and infant anti-HAV antibodies (n = 0.96, p < 0.001) on admission. Hepatitis A vaccine showed no immunogenicity in infants with presence of maternal antibodies. Hepatitis A vaccine is safe but it should be used after the disappearance of maternal antibodies.     

The evaluation of vaccination against measles at nine months of age (report of an epidemic).

Sixteen measles cases were studied during an epidemic that broke out in Etimesgut district of Ankara. Eight of these children had never been vaccinated against measles while the remainder had been vaccinated at nine months of age. In the sera obtained during the course of the illness, anti-measles antibody was not detectable in six vaccinated children and in four unvaccinated children. Upon observing the siblings of the subjects, it was determined that one out of three who had not been vaccinated against measles and three out of seven who had been vaccinated at nine months of age contracted the disease within a month. However none of the siblings who had been vaccinated against measles at 15 months contracted the disease. In our cases, although vaccination at nine months of age could not prevent measles, it resulted in a milder form of the disease. It seems that measles vaccine administered to infants at around nine months of age does not prevent the occurrence of the disease in many children.     

Immunization by inhalation of aerosolized measles vaccine.

The importance of effectively protecting infants against measles is substantial because of the number of lives that can be saved and the morbidity that can be prevented. (i) Infants contract measles before the recommended age of immunization. (ii) Circulating maternal antibodies render measles vaccination ineffective in many infants. These problems have led to clinical trials of immunizing infants using routes other than the usual subcutaneous one. One promising approach is the inhalation of aerosolized vaccine. This study was undertaken to try to immunize very young infants using easily accessible vaccine and ordinary equipment. Infants aged 4-6 months were selected for measles immunization by inhalation. They were clinically well, with no history of tuberculosis or asthma. From each child, 0.2 ml of blood was obtained by finger-prick. The blood was kept on ice, then centrifuged and the serum stored in a freezer at -20 degrees C. Each child was weighed and clinically assessed and his rectal temperature recorded. Using a plastic nebulizer to hold reconstituted vaccine by SCLAVO of Italy and an ordinary foot pump, the vaccine was aerosolized. One thousand TCID50 of the vaccine was administered to each child with a vinyl face mask for a period of at least 30 s, to allow him to retain 250 TCID50. The child was then clinically followed up three times a week for 4 weeks with particular reference to (i) fever, (ii) conjunctivitis, (iii) cough, and (iv) skin rash. None of the infants developed any of the above signs during the interval.(ABSTRACT TRUNCATED AT 250 WORDS)     

Experience with a measles vaccine manufactured in India.

Five hundred and twenty seven children between 7 months and 2 years of age were vaccinated with measles vaccine manufactured by the Serum Institute of India. The sero-conversion rate in children who had no antibodies previous to vaccination was 98.4% as tested in HI. Ninety per cent of children who had pre-vaccination measles antibodies showed a two-fold or more rise in HI antibodies. The side reactions of the vaccine were negligible.     

Measles, mumps and rubella immunization at nine months in a developing country

The antibody responses and reactogenicity of a measles, mumps and rubella vaccine in 9-month-old and 15-month-old black children in South Africa were compared. The antibody response to the measles component was marginally better in the older group, but no differences were observed in the response to the mumps and rubella components. Reactogenicity was similar in the two age groups. Therefore it is possible that a trivalent measles, mumps and rubella vaccine can safely and effectively replace routine measles immunization at 9 months of age in this population. Whether routine immunization policy should incorporate such a vaccine depends on the extent of acceptance of measles vaccination. In urban populations of developing countries with high rates of measles immunization, routine vaccination at 9 months might interrupt circulating wild type rubella and provide sufficient herd immunity to protect susceptible women of childbearing age. It also should decrease significantly the complications associated with wild type mumps infection. The replacement of measles vaccine by a trivalent vaccine may be very cost-effective.     

Comparison of high titer Edmonston-Zagreb, Biken-CAM and Schwarz measles vaccines in Peruvian infants.

In an effort to identify the optimal dose and strain of measles vaccination for early immunization, Peruvian infants were randomly assigned to receive one of three measles vaccines in varying doses at 5 to 6 or 8 to 9 months of age. Edmonston-Zagreb vaccines were significantly (P < 0.001) more immunogenic than equivalent or higher titers of Schwarz or Biken-CAM vaccines as determined by neutralization antibody response 3 months after vaccination. Eighty-two percent of infants who received high titer Edmonston-Zagreb vaccine at 5 to 6 months of age developed protective concentrations of measles antibody, a response rate similar to that observed after standard titer Schwarz (81%) or high titer Biken-CAM vaccine (81%) at 8 to 9 months of age. No significant differences in the rates of fever, rash or other adverse events were noted by vaccine group 10 to 14 days after vaccination. Although the high titer vaccines are more immunogenic in young infants than standard vaccines, long term safety must be assured before these vaccines can be put into widespread use.     

Prevalence of placentally transmitted antibodies for measles in infants 3 to 11 months old in an urban slum community

Upto 35% of infants aged between 6 and 11 months are infected with measles in India with its associated high morbidity and mortality. The objective of the study is to know the waning pattern of placentally transmitted antibodies (PTA) for measles so that the age at which children are likely to become susceptible to measles infection could be identified. A cross-sectional serological survey of children aged 3 to 11 months in one of the Integrated Child Development Service (ICDS) area in Madras city slums was done. Venous blood from 376 children was collected and was tested for Hemagglutination Inhibition (HI) antibodies by standard microtitration technique. Titre greater than or equal to 1:8 has been considered as protective. The proportion of children with immune level and the Geometric Mean Titre (GMT), declined to the least by 5 months which denotes that most of the infants become susceptible to measles infection from as early as 5 months of age. There is no significant difference in the waning pattern between different age groups, sex and nutritional status. A community study for effectiveness of measles vaccine at 6-8 months of age is needed to know the feasibility of immunization earlier than 9 months of age.     

Successful immunization of infants at 6 months of age with high dose Edmonston-Zagreb measles vaccine. Cite Soleil/JHU Project Team

A group of 2097 Haitian infants 6 to 11 months of age were randomized to receive Schwarz or Edmonston-Zagreb strain measles vaccines containing 10- to 500-fold more vaccine viral particles than standard potency vaccines. No unusual adverse reactions were noted. Edmonston-Zagreb vaccines were more effective than equivalent doses of Schwarz vaccines as measured by the proportion of vaccinated children with measles antibody concentrations greater than or equal to 200 mIU/ml 2 months after vaccination and the persistence of antibody at 18 to 24 months of age. High titer Edmonston-Zagreb vaccine administered at 6 months of age induced antibody concentrations greater than or equal to 200 mIU/ml in 83% of infants by plaque reduction neutralization and 93% of infants by enzyme-linked immunosorbent assay with high rates of antibody persistence at 12 to 24 months of age. The World Health Organization recommends high titer Edmonston-Zagreb measles vaccines for routine use at 6 months of age in areas where measles is an important cause of mortality in young infants.     

Childhood survival in Haiti: protective effect of measles vaccination

To evaluate the impact of measles vaccination on survival of children residing in a periurban slum in Haiti, a total-population survey was conducted 2.5 years after completion of a one-time study of the serologic response to measles vaccine administered in the same population. Pregnancy histories from the 16,400 women in the population revealed that 1499 children had been born during a 7-month interval that would have made them eligible for participation in the measles vaccine program. Of these children, 1381 (92.1%) survived to 9 months of age, the median age that measles vaccine had been administered. Seventy-three infants had died between 9 and 39 months of age. Mortality of infants who were seronegative before receiving measles vaccine was significantly lower (P = .0013) than that of unvaccinated infants (3/235 vs 70/1056, respectively). Other factors positively associated with survival between 9 and 39 months of age included socioeconomic status (P = .0002), maternal literacy (P = .0020), maternal knowledge and use of oral rehydration solution (P = .0002), and an interval of greater than 24 months to the birth of the next younger sibling (P = .0012). Multivariate stepwise logistic regression analysis was used to evaluate the independent association of measles vaccination by adjusting for other factors that also correlated with survival and that might have been associated with maternal seeking of vaccinations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of monovalent measles and trivalent measles-mumps-rubella vaccines at various ages and concurrent administration with hepatitis B vaccine

To determine the most suitable vaccination schedule in developing countries, a study was conducted to reevaluate the immunogenicity of monovalent measles vaccine and trivalent measles-mumps-rubella vaccine at different ages. The success rate of measles vaccination was 84% at 9 months, 88% at 12 months and 100% at 15 months of age. Vaccination with measles vaccines at 9 and 15 months of age was also 96% immunogenic. Most vaccinees (16 of 17) not responding to the first measles vaccine before 1 year of age developed measles antibody with another shot of vaccine after 15 months of age. Trivalent measles-mumps-rubella vaccine worked well in children ages 14 to 18 months. Administering trivalent vaccine and hepatitis B vaccine concurrently at 1 year of age, rubella and mumps antibodies developed in more than 95% of vaccinees, while measles antibody was detected in 88%. Responses to hepatitis B vaccine in this situation were good; 89% of vaccinees developed antibody against hepatitis B surface antigen (greater than or equal to 10 mIU/ml) and the geometric mean titer was 362.49 mIU/ml. In summary vaccination twice at 9 and 15 months is effective and is a useful regimen in developing countries where measles is still endemic. Trivalent vaccine and hepatitis B vaccine will not interfere with each other when given together at 1 year of age.     

Hepatitis A seroprevalence among infants aged 12 months in Ankara

Seroprevalence studies in various age groups contribute to a better understanding of hepatitis A infection and response to hepatitis A immunization. Hepatitis A seroprevalence in 12-month-old infants from Ankara was studied. Among 601 healthy infants, overall hepatitis A seropositivity was found to be 23.5%. There were no gender differences in seropositivity (22.6% for male and 24.5% for female infants). Although vaccination of infants would be an ideal prevention strategy, presence of maternal anti-hepatitis A virus (HAV) antibody interferes with the immune response to hepatitis A vaccine in infants and young children. Therefore, further knowledge about decay of maternal antibody in infants is important in determining the optimal age for vaccination against hepatitis A. There is no recommendation for routine hepatitis A vaccination in Turkey. However, we need more seroprevalence studies in different age groups to decide the appropriate timing/age of vaccination.