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J Infect Dis. 2019 Mar 14. pii: jiz124. doi: 10.1093/infdis/jiz124. [Epub ahead of print]

Rapid Disappearance of Poliovirus Type 2 Immunity in Young Children Following Withdrawal of Oral Poliovirus Type 2 Containing Vaccine in Vietnam.

Author information

1
National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
2
Polio Eradication Department, World Health Organization, Geneva, Switzerland.
3
Pasteur Institute, Ho Chi Minh city, Vietnam.
4
Division of Viral Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.

Abstract

BACKGROUND:

Due to global shortage of inactivated poliovirus vaccine and global withdrawal of poliovirus type-2 (PV2) containing oral vaccine in May 2016, Vietnam has not used any PV2-containing vaccine between May 2016-October 2018. We assessed population immunity gap to PV2.

METHODS:

A cross-sectional survey in children 1-18 months of age was carried out in January 2018: one blood sample was obtained and analysed for the presence of poliovirus neutralizing antibodies. In children with detectable anti-PV2 antibodies, a second blood sample was obtained and analysed four months later to distinguish between passive (maternally-derived) and active (induced by secondary transmission or vaccination) immunity.

RESULTS:

Analysable sera were obtained from 1,106/1,110 enrolled children. Seroprevalence of PV2 antibodies was 87/368 (23.6%) among 1-7-month-old; 27/471 (5.7%) in the 8-15-month-old; and 19/267 (7.1%) in the 16-18-month-old. Seroprevalence declined with age in the 1-7 month-old group, and in children 8-18 months it remained without significant change by age. Four months later, 11/87 (14%), 9/27 (32%), and 12/19 (37%) remained seropositive in the 1-7, 8-15, and 16-18-month groups, respectively.

INTERPRETATION:

We found declining immunity to PV2, suggesting that Vietnam is at risk for an outbreak of type 2 vaccine-derived poliovirus in case of importation or new emergence.

PMID:
30869149
DOI:
10.1093/infdis/jiz124

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