1459. The Pregnancy Vaccine Effectiveness Network (PREVENT): Establishing a Multi-Country Cohort to Estimate Vaccine Effectiveness (VE) against Hospitalized Influenza during Pregnancy
Session: Poster Abstract Session: Influenza and Influenza Vaccines
Friday, October 6, 2017
Room: Poster Hall CD

Pregnant women are at greater risk of complications from influenza (flu) infection than the general population. Although vaccination is an effective method to prevent influenza, the vaccine is underutilized during pregnancy. A challenge to maternal flu vaccination is the paucity of data about the effectiveness of inactivated influenza vaccines (IIV) in preventing severe outcomes in pregnant women. To inform policy and address this knowledge gap, CDC developed a multi-country collaboration to investigate the preventive value of IIV during pregnancy during multiple flu seasons. We present the progress to date of this Network.


PREVENT was established in April 2016 to: i) estimate incidence of influenza and vaccination rates; ii) describe epidemiologic characteristics associated with illness; and iii) estimate IIV effectiveness in preventing hospitalizations during pregnancy associated with RT PCR -confirmed influenza. We selected sites that could identify the population of women known to be pregnant during flu seasons and integrate their hospitalization data, clinical laboratory testing, and vaccination records. We will assess VE using the case test-negative control design and use meta-analyses to pool VE estimates across sites and account for significant differences. Primary analyses will be completed by August 2017.


Seven sites in Australia, Canada, Israel, and the US were selected; a protocol and data dictionary were finalized. We identified 1,024 pregnant women hospitalized with acute respiratory illness and RT-PCR tested, during six influenza seasons (2010-11 through 2015-16). Of the qualifying women, 550 (54%) tested positive for flu. Positivity varied by site (range 41% (US) - 61.8% (Ontario, CAN)), and vaccination coverage varied across sites and seasons (range 7.3% (Ontario, CAN) - 46% (US)). Analyses will examine flu season characteristics, vaccination patterns, and clinical and birth outcomes related to respiratory illness during pregnancy and flu incidence.


Laboratory-confirmed influenza hospitalization during pregnancy is a relatively low-frequency event. Pooling data across multiple sites offers a way to estimate VE against severe influenza outcomes in pregnant women that is informative to influenza vaccine policy.

Sarah Ball, MPH, ScD1, Allison Naleway, PhD2, Jeffrey C. Kwong, MD3, Annette K. Reagan, PhD, MPH, MinfDis4, Kimberley Simmonds, PhD5, Becca Feldman, ScD, MS6, Eduardo Azziz-Baumgartner, MD, MPH7, Brandy Wyant, MPH8, Nicola P. Klein, MD, PhD9, Deshayne Fell, PhD10, Paul Effler, MD, MPH11, Stephanie Booth, MPH12, Mark Katz, MD6, Fatimah S. Dawood, MD7, Patricia Shifflett, RN, MS8, Michael L. Jackson, PhD, MPH13, Sarah Buchan, ScH, MSc3, Avram Levy, PhD6, Steven Drews, PhD5, Shikha Garg, MD, MPH7, Stephanie Irving, MHS2, Margaret L. Russell, MD PhD12, Edwin Lewis, MPH9, Bradley Crane, MS2, Sharareh Modaressi, MD, MPH9, Matthew Slaughter, MSBA2, Kristin Goddard, MPH9 and Mark G. Thompson, PhD7, (1)Division of Health and Environment, Abt Associates, Cambridge, MA, (2)Kaiser Permanente Center for Health Research, Portland, OR, (3)Institute for Clinical Evaluative Sciences, Toronto, ON, Canada, (4)Curtin University, Perth, Australia, (5)University of Calgary, Calgary, AB, Canada, (6)Clalit Research Institute, Tel Aviv, Israel, (7)Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, (8)Abt Associates, Cambridge, MA, (9)Kaiser Permanente Vaccine Study Center, Oakland, CA, (10)Ottawa Hospital Research Institute, Ottawa, ON, Canada, (11)Communicable Disease Control Directorate, Perth, Australia, (12)Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada, (13)Kaiser Permanente Washington Health Research Institute, Seattle, WA


S. Ball, None

A. Naleway, MedImmune: Investigator , Research grant
Pfizer: Investigator , Research grant
Merck: Investigator , Grant recipient

J. C. Kwong, None

A. K. Reagan, None

K. Simmonds, None

B. Feldman, None

E. Azziz-Baumgartner, None

B. Wyant, None

N. P. Klein, GSK: Investigator , Research grant
Sanofi Pasteur: Investigator , Grant recipient
Merck & Co: Investigator , Grant recipient
MedImmune: Investigator , Grant recipient
Protein Science: Investigator , Research grant
Pfizer: Investigator , Grant recipient

D. Fell, None

P. Effler, None

S. Booth, None

M. Katz, None

F. S. Dawood, None

P. Shifflett, None

M. L. Jackson, None

S. Buchan, None

A. Levy, None

S. Drews, None

S. Garg, None

S. Irving, Medimmune/AstraZeneca: Investigator , Research support

M. L. Russell, None

E. Lewis, None

B. Crane, None

S. Modaressi, None

M. Slaughter, None

K. Goddard, None

M. G. Thompson, None

Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 4th with the exception of research findings presented at the IDWeek press conferences.