2009 pandemic influenza A (H1N1) in pregnancy: a systematic review of the literature

Mosby, Laura G.; Rasmussen, Sonja A.; Jamieson, Denise J.

doi:10.1016/j.ajog.2010.12.033

Cited by 319 publications

(263 citation statements)

References 114 publications

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“…For instance, in the 1918 influenza pandemic, a case series described mortality rates of 27% in pregnant women compared with 1% in the general population, and, in the 1957 pandemic, 50% of influenza deaths among reproductive aged women in Minnesota were in those that were pregnant (5,6). During the 2009 H1N1 pandemic, although pregnant women constituted only ∼1% of the population, they accounted for 5-7% of the deaths, hospitalizations, and intensive care unit admissions, with increased risk observed in the second and third trimesters (7,8). Pregnant women and women planning to become pregnant have therefore been identified as a priority group to receive the influenza vaccine; however, only 50% of pregnant women or women who planned to become pregnant during the influenza season received the vaccine in 2012 (9).…”

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confidence: 99%

Enhanced natural killer-cell and T-cell responses to influenza A virus during pregnancy

Kay¹,

Fukuyama²,

Aziz

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Pregnant women experience increased morbidity and mortality after influenza infection, for reasons that are not understood. Although some data suggest that natural killer (NK)-and T-cell responses are suppressed during pregnancy, influenza-specific responses have not been previously evaluated. Thus, we analyzed the responses of women that were pregnant (n = 21) versus those that were not (n = 29) immediately before inactivated influenza vaccination (IIV), 7 d after vaccination, and 6 wk postpartum. Expression of CD107a (a marker of cytolysis) and production of IFN-γ and macrophage inflammatory protein (MIP) 1β were assessed by flow cytometry. Pregnant women had a significantly increased percentage of NK cells producing a MIP-1β response to pH1N1 virus compared with nonpregnant women pre-IIV [median, 6.66 vs. 0.90% (P = 0.0149)] and 7 d post-IIV [median, 11.23 vs. 2.81% (P = 0.004)], indicating a heightened chemokine response in pregnant women that was further enhanced by the vaccination. Pregnant women also exhibited significantly increased T-cell production of MIP-1β and polyfunctionality in NK and T cells to pH1N1 virus pre-and post-IIV. NK-and T-cell polyfunctionality was also enhanced in pregnant women in response to the H3N2 viral strain. In contrast, pregnant women had significantly reduced NK-and T-cell responses to phorbol 12-myristate 13-acetate and ionomycin. This type of stimulation led to the conclusion that NK-and T-cell responses during pregnancy are suppressed, but clearly this conclusion is not correct relative to the more biologically relevant assays described here. Robust cellular immune responses to influenza during pregnancy could drive pulmonary inflammation, explaining increased morbidity and mortality.

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mentioning

confidence: 99%

Enhanced natural killer-cell and T-cell responses to influenza A virus during pregnancy

Kay¹,

Fukuyama²,

Aziz

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…A systematic literature review in 2011 that included reports from 29 countries around the world regarding the influenza A/H1N1 pandemic in 2009 found that pregnant women accounted for 6.3% of the hospitalizations, 5.9% of the intensive care unit admissions and 5.7% of deaths that were associated with A/H1N1pdm09 infection; although pregnant women comprise only about 1% of the total population in the USA for example. 4 In pooled data from another systematic review, the average case fatality rate for pregnant women infected with A/H1N1pdm09 was 6.4% (range 0% in Japan to 25% in India) using available data from 10 countries. 5 The highest risk groups for severe complications were described to be women in their second and particularly the third trimesters of pregnancy or pregnant women with underlying medical conditions, although severe illness with intensive care unit admissions and death occurred in all 3 trimesters and among women in whom the only recognized risk factor was pregnancy.…”

Section: Pregnant Women Are At High Risk For Influenza-related Complimentioning

confidence: 99%

Review on the effects of influenza vaccination during pregnancy on preterm births

Nunes

Madhi

2015

Human Vaccines & Immunotherapeutics

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“…4–6 Also, vaccination of pregnant women with influenza vaccine is now recommended in many high and middle-income countries, and increasingly so for acellular pertussis vaccine, 7–9 aimed at protecting their young infants primarily through transplacental transfer of IgG antibodies to the fetus. Other mechanisms which might be involved in conferring protection to the infant following maternal vaccination include enhancing transmission of breastmilk antibodies (IgA) induced by vaccines 10 , 11 ; as well as the mother being less susceptible to infection from the targeted pathogen and being less infectious to her young infant.…”

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confidence: 99%

Experience and challenges on influenza and pertussis vaccination in pregnant women

Madhi

Nunes

2018

Human Vaccines & Immunotherapeutics

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Young infants contribute to relatively high burden of vaccine-preventable diseases, including infections by influenza virus and Bordetella pertussis. Vaccination of pregnant women can enhance transplacental transfer of protective antibody to the fetus and protect the infant against disease during the first few months of life.Pregnant women are a priority group for seasonal influenza vaccination, due to third-trimester pregnancy being a risk-factor for severe influenza illness. Furthermore, randomized controlled trials confirmed that influenza vaccination during pregnancy confers protection against influenza-confirmed illness in the women, and their infants up to 3 months of age; and is also associated with 20% reduction in all-cause pneumonia among young-infants. Maternal influenza vaccination might also reduce the risk of low-birth weight, preterm births, and stillbirths however, data on this is conflicting.Vaccination of pregnant women with acellular pertussis vaccines reduces pertussis in their young infants by up to 93%. The increase in specific pertussis antibody among the infants born to vaccinated women might, however, interfere with the active pertussis vaccination of the infant following the primary series of vaccines. The clinical implication of this is yet to be ascertained, particularly since immune responses following the booster vaccine are unaffected.Vaccination of pregnant women with inactivated influenza vaccine and acellular pertussis vaccine have been demonstrated to confer protection to their young infants, and warrants consideration for inclusion into public health immunization programs, including in low and middle income countries.

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2009 pandemic influenza A (H1N1) in pregnancy: a systematic review of the literature

Cited by 319 publications

References 114 publications

Enhanced natural killer-cell and T-cell responses to influenza A virus during pregnancy

Enhanced natural killer-cell and T-cell responses to influenza A virus during pregnancy

Review on the effects of influenza vaccination during pregnancy on preterm births

Experience and challenges on influenza and pertussis vaccination in pregnant women

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