Biomaterial Database

Partial uptake of varicella vaccine and the epidemiological effect on varicella disease in 11 day-care centers in North Carolina. 2001

D A Clements, and J I Zaref, and C L Bland, and E B Walter, and P M Coplan

Campus Box 3810, Duke University Medical Center, Durham, NC 27710, USA. cleme002@mc.duke.edu

BACKGROUND The increasing use of varicella vaccine in children attending day care has rapidly decreased the incidence of wild-type varicella disease. The herd immunity noted is significant and will have an effect on the epidemiology of natural varicella. OBJECTIVE To monitor the change in varicella incidence in day-care attendees after the licensure of varicella vaccine. METHODS A prospective observational cohort study design. METHODS Eleven private day-care centers and preschools in North Carolina participated in the study from January 1, 1995, through December 31, 1999. METHODS All children in the 11 centers were eligible for participation. Some participated more actively, supplying information on a regular basis. Others participated passively. Day-care personnel provided information about all cases of varicella. METHODS None. METHODS The change in the incidence of varicella disease was documented as the use of varicella vaccine increased. RESULTS Varicella vaccine coverage increased substantially from 4.4% in 1995 to 63.1% in December 1999. The vaccination rate accelerated dramatically in 1996 and 1997, leveled off in 1998, and rose again in 1999. Cumulative varicella incidence decreased from 16.74 cases per 1000 person-months in July 1996 to 1.53 cases per 1000 person-months in December 1999 in unvaccinated children. CONCLUSIONS The varicella vaccination rate continued to increase slowly in the day-care population after an initial rapid uptake. The decrease in varicella disease is greater than the increase in varicella vaccination. This herd effect is welcome and even apparent in the unvaccinated children younger than 1 year.

UI	MeSH Term	Description	Entries
D007114	Immunization	Deliberate stimulation of the host's immune response. ACTIVE IMMUNIZATION involves administration of ANTIGENS or IMMUNOLOGIC ADJUVANTS. PASSIVE IMMUNIZATION involves administration of IMMUNE SERA or LYMPHOCYTES or their extracts (e.g., transfer factor, immune RNA) or transplantation of immunocompetent cell producing tissue (thymus or bone marrow).	Immunologic Stimulation,Immunostimulation,Sensitization, Immunologic,Variolation,Immunologic Sensitization,Immunological Stimulation,Sensitization, Immunological,Stimulation, Immunologic,Immunizations,Immunological Sensitization,Immunological Sensitizations,Immunological Stimulations,Sensitizations, Immunological,Stimulation, Immunological,Stimulations, Immunological,Variolations
D007223	Infant	A child between 1 and 23 months of age.	Infants
D007231	Infant, Newborn	An infant during the first 28 days after birth.	Neonate,Newborns,Infants, Newborn,Neonates,Newborn,Newborn Infant,Newborn Infants
D008297	Male		Males
D009657	North Carolina	State bounded on the north by Virginia, on the east and Southeast by the Atlantic Ocean, on the south by Georgia and South Carolina, and on the west by Tennessee.
D011446	Prospective Studies	Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.	Prospective Study,Studies, Prospective,Study, Prospective
D002644	Chickenpox	A highly contagious infectious disease caused by the varicella-zoster virus (HERPESVIRUS 3, HUMAN). It usually affects children, is spread by direct contact or respiratory route via droplet nuclei, and is characterized by the appearance on the skin and mucous membranes of successive crops of typical pruritic vesicular lesions that are easily broken and become scabbed. Chickenpox is relatively benign in children, but may be complicated by pneumonia and encephalitis in adults. (From Dorland, 27th ed)	Varicella,Chicken Pox
D002656	Child Day Care Centers	Facilities which provide care for pre-school and school-age children.	Day Care Centers for Children,Child Daycare Centers,Daycare Centers for Children,Child Daycare Center
D002675	Child, Preschool	A child between the ages of 2 and 5.	Children, Preschool,Preschool Child,Preschool Children
D004198	Disease Susceptibility	A constitution or condition of the body which makes the tissues react in special ways to certain extrinsic stimuli and thus tends to make the individual more than usually susceptible to certain diseases.	Diathesis,Susceptibility, Disease,Diatheses,Disease Susceptibilities,Susceptibilities, Disease