has reviewed the limited data which are available and recommends 2 intramuscular injections of the split-virus bivalent A influenza vaccine separated by at least 4 weeks. For these infants and young children a dose of 0.25 ml should be used. This volume represents 50% of the dose used in older children and adults and contains 100 CCA units each of A/New Jersey/76 (swine influenza virus) and A/Victoria/75.

High-risk children and adolescents 3-17 years old: See previous recommendation of the American Academy of Pediatrics Committee on Infectious Diseases, "Immunization of Children at High Risk from Influenza Infection," September 1976.

High-risk young adults 18-24 years old: A second dose of either whole-virus or split-virus bivalent A influenza vaccine containing 200 CCA units of A/New Jersey/76 (swine influenza virus) and 200 CCA units of A/Victoria/75 at least 4 weeks after the first dose.

Monovalent B/Hong Kong/72 Vaccine for High-Risk Children and Adolescents

Recommended dosages of influenza A vaccines for children have been derived in large part from the current field trials in relevant age groups and from clinical experience and judgment. Studies of influenza B vaccines have been much less extensive. In the absence of new data on which

INTRODUCTION

to base dosages of the monovalent B vaccine containing 500 CCA units of B/Hong Kong/72 generally recommended for children at risk of serious or fatal influenza, it is reasonable to employ dosage concepts used in past years. This has been for fractional doses of vaccine according to age group, derived, in part, empirically. It is represented in package literature for the monovalent B/Hong Kong influenza vaccine for use in 1976. A single dose of this vaccine is believed to be sufficient for high-risk children because of their likely prior natural exposures to related influenza B strains. The following single-dose schedules of monovalent B/Hong Kong influenza vaccine are recommended:

Infants and children less than 3 years old: No recommendation.

Children 3-5 years old: 0.05 ml to 0.1 ml (this volume represents 10-20% of the adult dose and contains 50-100 CCA units of antigen). (A second dose of the same volume 2 weeks or more later has sometimes been recommended to add to the initial antigenic stimulus.)

Children 6-9 years old: 0.25 ml (this volume represents 50% of the adult dose and contains 250 CCA units of antigen).

Children 10-17 years old: 0.5 ml (this volume is the same as that recommended for adults and contains 500 CCA units of antigen).

Measles is often a severe disease, frequently complicated by middle ear infection and bronchopneumonia. Encephalitis, which occurs with approximately 1 of every 1,000 reported cases of measles, often causes permanent brain damage and mental retardation. Death, predominantly from respiratory and neurologic causes, is associated with measles in 1 of every 1,000 reported cases.

With the highly effective, safe vaccines now available, measles could be completely controlled in the United States. Collaborative efforts of professional and voluntary medical and public health organizations in vaccination programs have resulted in a dramatic reduction in the incidence of measles. A continuing effort to vaccinate all susceptible children and to revaccinate those whose immunity is questioned is necessary if the goal of eradicating measles is to be reached.

MEASLES VIRUS VACCINE

Live measles virus vaccine* available in the United States is prepared in chick embryo cell culture. The current vaccine virus strain has been attenuated beyond that of the original Edmonston B strain, which is now rarely used. Measles vaccine produces a mild or inapparent, non-communicable infection. Fifteen percent of vaccinated children have fever (rectal temperature 103 F) beginning about the sixth day after vaccination and lasting up to 5 days. Transient, atypical rashes have been reported, but rarely. Most reports indicate that children with fevers are otherwise asymptomatic.

Measles antibodies develop in at least 95% of susceptible children vaccinated at about 15 months of age or older with

*Official name: Measles Virus Vaccine, Live, Attenuated.

the more attenuated measles vaccine. The titers of vaccineinduced antibody are lower than those following natural disease; but the conferred protection appears to be durable, judging from evidence now extending to 14-year follow-up.

Seroconversion rates following vaccination of children about 12 months of age are somewhat lower than at 15 months; rates in vaccinees 13-14 months old have not been as thoroughly evaluated but appear to be higher than in 12-month-olds. Children vaccinated prior to 12 months of age, particularly when only 6-9 months, generally have lower rates of seroconversion. Residual maternal antibody apparently can interfere with measles immunization up to about 1 year of age or more.

Experience with more than 80 million doses of vaccine distributed in the United States through 1975 indicates that live measles vaccine has an excellent record of safety. Adverse reactions temporally associated with measles vaccination, those of the central nervous system including encephalitis and encephalopathy, reportedly occur approximately once for every million doses.

Subacute sclerosing panencephalitis (SSPE) is a "slow virus" infection of the central nervous system associated with a measles-like virus. Preliminary results from a casecontrol study indicate that measles vaccine significantly reduces the chance of developing SSPE. However, there have been reports of SSPE in children who did not have a history of natural measles but did receive measles vaccine. Some of these cases may have resulted from unrecognized measles illness in the first year of life or possibly from the measles vaccination. Based on estimated nationwide measles morbidity data and nationwide measles vaccine distribution, the association of SSPE cases to measles vaccination is about 1 case per million vaccin

'istributed. This is

All susceptible children those who have not had natural measles or measles vaccine - should be vaccinated. It is particularly important to vaccinate them at about 15 months of age, before they encounter other susceptible children in day-care centers, nursery schools, kindergartens, or elementary schools. Unvaccinated preschool and elementary-school children are often responsible for transmitting measles to other children in the community.

Dosage: A single dose of live measles vaccine in volume specified by the manufacturer should be given subcutaneously. No booster is needed. Immune serum globulin (ISG) should not be given with the currently available measles vaccine.

Age: To achieve the maximum rate of seroconversion, measles vaccine preferably should be given when children are about 15 months of age or at least have passed their first birthday. However, whenever there is a likely exposure to natural measles at an earlier age, infants as young as 6 months old should be vaccinated. In such cases, it should be recognized that since the rate of seroconversion declines with diminishing age, the children may need to be revaccinated at an older age to assure continued protection.

With the recent shift in age distribution of reported measles cases to older groups, vaccination may be indicated for high school and college age persons in epidemics. Limited data show that adverse reactions to vaccine are no more common in adults than in children.

Revaccination: Children vaccinated before 12 months of age particularly if vaccine was administered with ISG or measles immune globulin (MIG), a standardized globulin preparation should be revaccinated with live measles vaccine at about 15 months of age to assure full protection. However, based on available evidence, there is no reason to systematically revaccinate all children originally vaccinated when 12-14 months of age. (See also "Prior Immunization with Inactivated Measles Virus Vaccine.")

High-risk groups: Immunization against measles is particularly important for children with illnesses such as heart disease, cystic fibrosis, and untreated tuberculosis and for children who are malnourished or are institutionalized. All these children are prone to have severe cases of measles and complications.

Use of Vaccine Following Exposure

Live measles vaccine given shortly after exposure to measles can provide protection. There is no contraindication to its use in exposed individuals. If the exposure does not result in infection, the vaccine should induce protection against subsequent infection.

Use of ISG Following Exposure

To prevent or modify measles in a susceptible person exposed less than 6 days before, ISG, 0.1 ml per pound of body weight, should be given. ISG may be especially indi

ed for susceptible household contacts of measles pa

tients, particularly contacts under 1 year of age, for whom the risk of complications is highest. Live measles vaccine should be given about 3 months later, if the contact is at least 15 months old, when the passive measles antibody should have disappeared. ISG should not be used in an attempt to control measles epidemics.

Precautions and Contraindications

Altered immunity: Replication of the measles vaccine virus can be potentiated in patients with immune deficiency diseases and by the suppressed immune responses that occur with leukemia, lymphoma, or generalized malignancy or with therapy with corticosteroids, alkylating drugs, antimetabolites, or radiation. Patients with such conditions should not be given live, attenuated measles virus vaccine.

Severe febrile illness: Vaccination should be postponed until the patient has recovered. Minor respiratory illnesses with low grade fever do not necessarily preclude vaccination.

Tuberculosis: Exacerbation of tuberculosis is known to occur with natural measles infection. By analogy, exacerbation might be associated with vaccination with the live, attenuated measles virus. Therefore, an individual known to have active tuberculosis should be under treatment when vaccinated.

Although tuberculin skin testing is a desirable part of ideal health care, it need not be a prerequisite to vaccination in communitywide measles immunization programs. The value of protection against natural measles far outweighs the theoretical hazard of possible exacerbation of unsuspected tuberculosis. If there is a need for tuberculin skin testing, it can be done on the day of vaccination and read 48-72 hours later.

Recent administration of Immune Serum Globulin: Vaccination should be deferred for about 3 months because passively acquired antibody might interfere with the response to vaccine.

Pregnancy: On grounds of a theoretical risk to the developing fetus, live, attenuated virus vaccines are not generally given to pregnant women. If, however, there is a risk of exposure to measles, there is no evidence that the measles vaccine cannot be given safely and effectively.

Hypersensitivity: (See ACIP "General Recommendations on Immunization, " MMWR 25(44):349, November 12, 1976.) Live measles vaccine is produced in chick embryo cell culture. It has not been reported to be associated with hypersensitivity reactions and can be given to all who need it. Vaccine should not be given to persons hypersensitive to vaccine components, such as trace amounts of particular antibiotics (see manufacturer's label).

Management of Patients with Contraindications

If immediate protection against measles is required for persons for whom live measles vaccine is contraindicated, passive immunization with ISG, 0.1 ml per pound of body weight, should be given as soon as possible after known exposure. It is important to note, however, that this dose of globulin, effective in preventing measles in normal children, may not be fully effective in children with acute leukemia. To decrease the risk of measles infection for such (Continued on page 365,