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Vaccine. 2014 Nov 12;32(48):6463-8. doi: 10.1016/j.vaccine.2014.09.054. Epub 2014 Oct 5.

Safety of inactivated monovalent pandemic (H1N1) 2009 vaccination during pregnancy: a population-based study in Taiwan.

Author information

1
Taiwan Centers for Disease Control, 6 Linsen S. Road, Taipei 10050, Taiwan. Electronic address: huangwt@ntu.edu.tw.
2
Taiwan Centers for Disease Control, 6 Linsen S. Road, Taipei 10050, Taiwan. Electronic address: pluto0507@hotmail.com.
3
Taiwan Centers for Disease Control, 6 Linsen S. Road, Taipei 10050, Taiwan. Electronic address: shuer@cdc.gov.tw.
4
Taiwan Centers for Disease Control, 6 Linsen S. Road, Taipei 10050, Taiwan. Electronic address: chih@cdc.gov.tw.
5
Taiwan Centers for Disease Control, 6 Linsen S. Road, Taipei 10050, Taiwan; Institute of Biomedical Informatics & Institute of Public Health, National Yang-Ming University, 155 Section 2, Linong Street, Taipei 11221, Taiwan. Electronic address: jhchuang@cdc.gov.tw.

Abstract

BACKGROUND:

Pregnant women were prioritized for H1N1 vaccination during the 2009-2010 pandemic. Safety concerns exist with vaccinating pregnant women, particularly in their first trimesters.

METHODS:

We linked computerized data on H1N1 vaccination, National Health Insurance, and Taiwan Birth Registry and identified events of spontaneous abortions (SABs) and all singleton births that occurred/delivered during November 1, 2009-September 30, 2010. The observation period for each case of SAB (6-19 weeks gestation) was divided into period at risk (1-28 days after vaccination) and control periods (the remaining person-days until SAB). The self-controlled case series method for truncated observational periods assessed the incidence rate ratio (IRR) of SAB during the 1-28 days compared with those in the control period. The case-control design matched each case of adverse fetal outcomes to up to 10 controls on fetal sex and year/month of pregnancy onset, and calculated matched odds ratio (OR) on H1N1 vaccination at <14 or ≥14 weeks gestation.

RESULTS:

Sixty-five women with SAB had received H1N1 vaccination at 6-19 weeks gestation. The IRR of SAB for the risk period 1-28 days was 1.03 (95% confidence interval [CI] 0.55-1.93). Among the 147,294 live births and 1354 stillbirths, maternal H1N1 vaccine receipt at <14 weeks gestation was associated with significantly reduced likelihood of small for gestational age (SGA) birth (OR 0.72, 95% CI 0.61-0.84) and birth defect (OR 0.46, 95% CI 0.22-1.00), whereas receipt at ≥14 weeks gestation was associated with significantly reduced likelihood of stillbirth (OR 0.63, 95% CI 0.46-0.86), prematurity (OR 0.90, 95% CI 0.83-0.97), low birth weight (OR 0.81, 95% CI 0.74-0.88), and SGA birth (OR 0.90, 95% CI 0.84-0.97).

CONCLUSIONS:

H1N1 vaccination during pregnancy did not increase risk of SAB or adverse fetal outcomes.

KEYWORDS:

H1N1 virus; MF59 adjuvant; Pregnancy; Taiwan; Vaccine safety

PMID:
25285884
DOI:
10.1016/j.vaccine.2014.09.054
[Indexed for MEDLINE]

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