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Influenza Vaccination of Pregnant Women and Serious Adverse Events in the Offspring.

ABSTRACT: Pregnant women are increasingly considered a priority group for influenza vaccination, but the evidence in favor relies mainly on observational studies, subject to the "healthy-vaccinee bias". Propensity score methods-sometimes applied-reduce but cannot eliminate residual confounding. Meta-analyses of observational studies show relative risks far from the thresholds that would confirm the efficacy of universal vaccination for pregnant women without needing randomized controlled trials (RCTs). Critical articles have shown that in the four RCTs investigating the outcomes of this vaccination, there was a tendency towards higher offspring mortality. In the largest RCT, there was a significant excess of presumed/serious neonatal infections, and also significantly more serious adverse events. Many widely acknowledged observational results (about hormone replacing therapy, vitamin D, omega-3 fatty acids, etc.) were confuted by RCTs. Therefore the international drive to consider this vaccination a "standard of care" is not justified yet. Moreover, there is the risk of precluding further independent RCTs for "ethical considerations", so as "to not deny the benefits of influenza vaccinations to pregnant women of a control group". Instead, before promoting national campaigns for universal vaccination in pregnancy, further large, independent, and reassuring RCTs are needed, even braving challenging a current paradigm. Until then, influenza vaccination should be offered to pregnant women only once open information is available about the safety uncertainties, to allow truly informed choices, and promoting also other protective behaviors.

SUBMITTER: Donzelli A

PROVIDER: S-EPMC6887964 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Influenza Vaccination of Pregnant Women and Serious Adverse Events in the Offspring.

Donzelli Alberto A

International journal of environmental research and public health 20191107 22

Pregnant women are increasingly considered a priority group for influenza vaccination, but the evidence in favor relies mainly on observational studies, subject to the "healthy-vaccinee bias". Propensity score methods-sometimes applied-reduce but cannot eliminate residual confounding. Meta-analyses of observational studies show relative risks far from the thresholds that would confirm the efficacy of universal vaccination for pregnant women without needing randomized controlled trials (RCTs). Cr ...[more]

PMID: 31703366

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Project description:ImportanceThe Advisory Committee on Immunization Practices (ACIP) recommends the tetanus, diphtheria, and acellular pertussis (Tdap) vaccine for pregnant women during each pregnancy, regardless of prior immunization status. However, safety data on repeated Tdap vaccination in pregnancy is lacking.ObjectiveTo determine whether receipt of Tdap vaccine during pregnancy administered in close intervals from prior tetanus-containing vaccinations is associated with acute adverse events in mothers and adverse birth outcomes in neonates.Design, setting, and participantsA retrospective cohort study in 29,155 pregnant women aged 14 through 49 years from January 1, 2007, through November 15, 2013, using data from 7 Vaccine Safety Datalink sites in California, Colorado, Minnesota, Oregon, Washington, and Wisconsin.ExposuresWomen who received Tdap in pregnancy following a prior tetanus-containing vaccine less than 2 years before, 2 to 5 years before, and more than 5 years before.Main outcomes and measuresAcute adverse events (fever, allergy, and local reactions) and adverse birth outcomes (small for gestational age, preterm delivery, and low birth weight) were evaluated. Women who were vaccinated with Tdap in pregnancy and had a prior tetanus-containing vaccine more than 5 years before served as controls.ResultsThere were no statistically significant differences in rates of medically attended acute adverse events or adverse birth outcomes related to timing since prior tetanus-containing vaccination. [table: see text].Conclusions and relevanceAmong women who received Tdap vaccination during pregnancy, there was no increased risk of acute adverse events or adverse birth outcomes for those who had been previously vaccinated less than 2 years before or 2 to 5 years before compared with those who had been vaccinated more than 5 years before. These findings suggest that relatively recent receipt of a prior tetanus-containing vaccination does not increase risk after Tdap vaccination in pregnancy.

Project description:Pregnant women and their newborns have an increased risk of developing severe influenza and influenza-related complications. In Germany, seasonal influenza vaccination is recommended for pregnant women since 2010. However, little is known about pregnant women's vaccination-related knowledge and attitudes, as well as their risk perceptions. This study therefore assessed pregnant women's vaccination-related knowledge, risk perceptions related to influenza disease and influenza vaccination during pregnancy, and aimed to identify determinants of influenza vaccination uptake during pregnancy in Germany.Between 2012 and 2014, a nationwide web-based prospective cohort study with follow-up interviews was conducted in initially pregnant women who gave birth over the study period. Control groups were set up in a cross-sectional fashion during the follow-up interviews. Women who participated in both, the baseline interview before giving birth and in the 1st interview after giving birth were included in the analysis. Univariate and multiple logistic regression were used to identify associations between influenza vaccination uptake and sociodemographic characteristics as well as items assessing attitude and knowledge.In total, 838 women were included in the analyses. Pregnant women had a positive attitude towards vaccination in general, but only modest vaccination knowledge. Overall, 10.9 % of women were vaccinated against seasonal influenza during pregnancy. While pregnant women perceived classical childhood diseases to be more risky than the respective vaccinations, this relation reversed for influenza: The risk of vaccination was perceived higher than the risk of the disease. These two types of risk perceptions independently determined influenza vaccination uptake-higher perception of disease risk and lower perceptions of vaccination-related risks increased uptake. Additionally, knowledge about the vaccination recommendation for pregnant women and a positive gynaecologist's attitude towards vaccination during pregnancy influenced the uptake significantly.Influenza vaccination uptake in pregnant women is low in Germany. Tailored communication strategies for pregnant women should focus especially on changing the perceptions of personal risks regarding influenza and influenza vaccination during pregnancy. Gynaecologists should be made aware about their crucial role in supporting vaccination decision-making of pregnant women and the need to provide relevant information to counteract misconceptions.

Project description:Nicaragua implemented an influenza vaccination program for pregnant women with high-risk obstetric conditions in 2007. In 2014, the recommendation of influenza vaccination expanded to include all pregnant women. Given the expansion in the recommendation of vaccination, we evaluated knowledge, attitudes and practices of pregnant women and their healthcare providers towards influenza vaccination and its recommendation.We conducted surveys among pregnant women and their healthcare providers from June to August 2016 at two hospitals and 140 health facilities in Managua. The questions were adapted from the U.S. national CDC influenza survey and related to knowledge, attitudes and practices about influenza vaccination and barriers to vaccination. We analyzed reasons for not receiving vaccination among pregnant women as well as receipt of vaccination recommendation and offer by their healthcare providers.Of 1,303 pregnant women enrolled, 42% (5?4?5) reported receiving influenza vaccination in the 2016 season. Of those who reported not receiving vaccination, 46% indicated barriers to vaccination. Pregnant women who were vaccinated were more likely to be aware of the recommendation for vaccination and the risks of influenza illness during pregnancy and to perceive the vaccine as safe and effective, compared to unvaccinated pregnant women (p-values?<?0.001). Of the 619 health workers enrolled, over 89% recalled recommending influenza vaccination to all pregnant women, regardless of obstetric risk. Of the 1,223 women who had a prenatal visit between the start date of the influenza vaccination and the time of interview, 44% recalled receiving a recommendation for influenza vaccination and 43% were offered vaccination. Vaccination rates were higher for those receiving a recommendation and offer of vaccination compared with those who received neither (95% vs 5%, p-value?<?0.001).Pregnant women in Managua had positive perceptions of influenza vaccine and were receptive to receiving influenza vaccination, especially after the offer and recommendation by their healthcare providers.

Dataset Information

Influenza Vaccination of Pregnant Women and Serious Adverse Events in the Offspring.

Publications

Influenza Vaccination of Pregnant Women and Serious Adverse Events in the Offspring.

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