Rubella seronegativity in antenatal screening - Is it influenced by the introduction of universal childhood rubella immunization?
OBJECTIVE
This study examined the impact of rubella immunization, implemented in Hong Kong in phases since 1978, on antenatal rubella serological status in Chinese women.


METHODS
In a retrospective cohort study, the incidence of antenatal rubella seronegative status in our parturients managed from 1998 to 2013 was analyzed by their year-of-birth as follows: <1965 (no childhood immunization), 1965-1982 (single dose at Primary 6), and ≥1983 (two doses at age 12 months and 12 years), adjusting for other factors including age, parity, body mass index, place-of-birth status and hepatitis B surface antigen (HBsAg) status.


RESULTS
Rubella seronegativity decreased from 12.9%, 10.5%, to 9.8% respectively, and correlated inversely (P<0.001) with year-of-birth cohorts. Despite similar demographic profiles, this correlation was found only in Hong-Kong-born women (from 12.6%, 7.5% to 6.5% respectively), who also had significant lower incidences of rubella seronegativity (OR 0.73, 0.31 and 0.29 respectively) and HBsAg seropositivity (OR 1.09, 0.63 and 0.48 respectively) than China-born women. On regression analysis, rubella seronegativity was actually significantly increased following the implementation of immunization (aOR 1.20) while it was the reverse for non-residents (aOR 0.61).


CONCLUSIONS
Although rubella seronegativity decreased with immunization, the effect was less than expected when adjusted for other risk factors.
Department of Obstetrics & Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong, China. Electronic address: lao-tt@cuhk.edu.hk.
Terence T
TT
Lao
Department of Obstetrics & Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong, China. Electronic address: daljit@cuhk.edu.hk.
Daljit S
DS
Sahota
Department of Obstetrics & Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong, China. Electronic address: lwlaw@cuhk.edu.hk.
Lai-Wa
LW
Law
Department of Obstetrics & Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong, China. Electronic address: tyleung@cuhk.edu.hk.
Tak-Yeung
TY
Leung
D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D005260:Female; D006723:Hong Kong; D006801:Humans; D017589:Immunization Programs; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012189:Retrospective Studies; D012409:Rubella / Q000517:prevention & control*; D012411:Rubella Vaccine / Q000008:administration & dosage*; D012412:Rubella virus / Q000276:immunology*; D016036:Seroepidemiologic Studies; D055815:Young Adult
D000914:Antibodies, Viral; D012411:Rubella Vaccine
Age; Body mass index; Hepatitis B virus infection; Multiparity; Multiple pregnancy; Rubella seronegativity; Universal immunization