Protection against varicella in family contacts by immediate inoculation with live varicella vaccine. Varicella vaccine studies in healthy children and adults. No evidence of an increase of bacterial and viral infections following Measles, Mumps and Rubella vaccine.
A live varicella vaccine (Oka strain) was given to susceptible household contacts of varicella to test the protective efficacy of the vaccination. Twenty-six contacts of 21 families were vaccinated, usually within three days after onset of the index cases. None of the vaccinated children developed clinical symptoms of varicella. Eighteen of 24 sera obtained before vaccination were found to be seronegative by complement fixation and neutralization tests. Seroconversion was observed in all of the 18. On the other hand, all of 19 unvaccinated contacts in the 15 families, who served as controls, showed typical manifestations of varicella from 10 to 33 days after onset of the index varicella cases. In three families, where only one sibling contact received vaccine and the other was an unvaccinated control, none of the vaccinated children showed any clinical symptoms while unvaccinated controls exhibited typical varicella symptoms 10 to 14 days after the onset of the index cases. These results indicate that varicella is prevented in household contacts by vaccination within three days following exposure. Immunization of normal children and adults with Oka strain live varicella vaccine from several manufacturers has been studied in our laboratory and elsewhere. This paper summarizes clinical trials designed to obtain information on minimum dose immunogenicity pre- and postexposure prophylaxis, immunization of various age groups, and booster immunizations for seropositive individuals. These studies documented a 94% to 100% seroconversion rate with 95% to 100% persistence of antibodies at 3 to 4 years. Protective efficacy was more than 90%, and the vaccine was successful in preventing varicella when a high dose was given postexposure. Clinical reactions were limited to temperature elevations and minor papulovesicular rashes that occurred in 5% to 10% of vaccinees. Herpes zoster has been absent in vaccinated healthy individuals. The suggestion that multi-antigen vaccines might overload the immune system has led to calls for single antigen vaccines. In 2003 we showed that rather than an increase there appeared to be a reduced risk of severe bacterial infection in the three months following Measles, Mumps and Rubella vaccine (MMR). The present analysis of illnesses in a general population is based on an additional 10 years of data for bacterial infections and also includes admissions with viral infections. Analyses were carried out using the self-controlled case-series method and separately for bacterial and viral infection cases, using risk periods of 0-30 days, 31-60 days and 61-90 days post MMR vaccine. An analysis was also carried out for those cases which were given MMR and Meningococcal serogroup C (MCC) vaccines concomitantly. A reduced risk was seen in the 0-30-day period for both bacterial infection (relative incidence=0.68, 95% CI 0.54-0.86) and viral infections (relative incidence=0.68, 95% CI 0.49-0.93). There was no increased risk in any period when looking at combined viral or bacterial infections or for individual infections with the single exception of an increased risk in the 31-60 days post vaccination period for herpes infections (relative incidence=1.69, 95% CI 1.06-2.70). For the children given Meningococcal group C vaccines concomitantly no significantly increased risk was seen in either the bacterial (relative incidence=0.54, 95% CI 0.26-1.13) or viral cases (relative incidence=0.46, 95% CI 0.11-1.93). Our study confirms that the MMR vaccine does not increase the risk of invasive bacterial or viral infection in the 90 days after the vaccination and does not support the hypothesis that there is an induced immune deficiency due to overload from multi-antigen vaccines.
These small trials suggest varicella vaccine administered within three days to children following household contact with a varicella case reduces infection rates and severity of cases. No RCTs for adolescents or adults were identified. However safety was not adequately addressed.