Influenza vaccination in pregnancy: careful assessment confirms safety concerns for the offspring

Abstract

Valid evidence does not support universal influenza vaccination for pregnant women, the LTE objections are unfounded. The observational evidence is less valid than that from RCTs: important safety signals in all the RCTs require high consideration. In RCTs, influenza vaccinated women have mostly local adverse effects, while their offspring shows a nonsignificant excess of deaths, and a significant excess of serious presumed/neonatal infections in the larger RCT. Several Authors have financial relationships with vaccine producers, several conclusions omit the safety signals. A cited systematic review has methodological problems and excluded important published RCTs. Waiting for new independent RCTs, the precautionary principle suggests avoiding to promote pregnant women vaccination. Health services could offer it highlighting existing uncertainties, with balanced informations allowing informed choices. ARTICLE HISTORY

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

“…A recently published retrospective cohort study [23] found no association between 2009 women given pandemic H1N1 vaccines in pregnancy and most five-year pediatric health outcomes. The study also cited the four RCTs commented below, but failed to mention some articles [5,6,24] which had questioned the reassuring conclusions of their authors, not supported by their own data. This omission occurred though one of the main authors [23] recently published a Comment [25] to these critics, receiving a Reply letter [24].…”

“…The study also cited the four RCTs commented below, but failed to mention some articles [5,6,24] which had questioned the reassuring conclusions of their authors, not supported by their own data. This omission occurred though one of the main authors [23] recently published a Comment [25] to these critics, receiving a Reply letter [24]. An Editorial of the retrospective study [23] concludes: “Vaccination of pregnant women saves lives” [26], but the RCTs tell a different story (Table 1).…”

“…In the placebo-controlled RCTs, the best evidence showed “very modest” efficacy of vaccination at the population level [2], and an excess of maternal local adverse effects [5,24]. Moreover, in the influenza-vaccinated women the offspring mortality tended to be higher than in the control groups.…”

“…Moreover, in the influenza-vaccinated women the offspring mortality tended to be higher than in the control groups. The overall serious adverse events (SAEs) tended to be more numerous, as summarized in an infographic [24]. In the larger RCT the excess of SAEs in the offspring was statistically significant, according to my personal calculation: the number of livebirths per vaccine group was 2064 in vaccinated women, 2041 in the active control group; the total SAEs were 225 (10.90%) and 175 (8.57%) respectively in Table S7 [28].…”

“…Since observational studies in pregnant women (usually quite young and healthy) are prone to the healthy-vaccinee bias, to promote a preventive pharmacological intervention, particularly in the vulnerable period of a pregnancy, public health services should not rely only or primarily on observational evidence [5,6,24]. Even more so if the (insufficient) safety evidence from existing RCTs shows a tendency to move in an opposite and alarming direction.…”