Safety of the HPV Bivalent and Quadrivalent Vaccines During Pregnancy

A Systematic Review of Population-Based Studies Assessing Knowledge, Attitudes, Acceptance, and Hesitancy of Pregnant and Breastfeeding Women towards the COVID-19 Vaccine

The anti-SARS-CoV-2 vaccination is recommended for pregnant women due to the high risk of complications. However, pregnancy has been associated with vaccine hesitancy. Our review aims at summarizing the existing literature about anti-SARS-CoV-2 vaccine hesitancy in pregnant and lactating women. The research was conducted on PubMed/MEDLINE, ExcerptaMedica Database (EMBASE), and Scopus, according to PRISMA guidelines. Articles regarding the COVID-19 vaccine's acceptance and/or refusal by pregnant and lactating women were selected. Only observational, population-based studies were included. The Joanna Briggs Institute quality assessment tools were employed. A total of 496 articles were retrieved, and after the selection process, 21 papers were included in the current analysis. All the included studies were cross-sectional, mostly from Europe and North America. The sample sizes ranged between 72 and 25,111 subjects. All of them included pregnant subjects, except one that focused on breastfeeding women only. Vaccine hesitancy rates ranged from 26% to 57% among different studies. Fear of adverse events and lack of knowledge were shown to be the main drivers of hesitancy. Approximately half of the studies (11/21) were classified as low quality, the remaining (9/21) were classified as moderate, and only one study was classified as high quality. Primigravidae were also shown to be more likely to accept anti-SARS-CoV-2 vaccination. Our findings confirm significant anti-SARS-CoV-2 vaccine hesitancy among pregnant women. Information gaps should be addressed to contain concerns related to adverse events.

Association of periconceptional or pregnancy exposure of HPV vaccination and adverse pregnancy outcomes: a systematic review and meta-analysis with trial sequential analysis

Objective: To evaluate whether periconceptional or pregnancy exposure of human papillomavirus (HPV) vaccination would increase the risk of adverse pregnancy outcomes. Methods: The PubMed, Web of Science, Embase, the Cochrane Library of clinical trials were searched from inception to March 2023. We computed relative risk (RR) and 95% confidence intervals (CIs) and prediction intervals (PIs) regarding the association between HPV vaccination in periconceptional period or during pregnancy and the risks of adverse pregnancy outcomes by using R software Version 4.1.2 and STATA Version 12.0. A trial sequential analysis (TSA) was performed with TSA v0.9.5.10 Beta software. Results: Four randomized controlled trials (RCTs) and eight cohort studies were included in this meta-analysis. Analysis of RCTs showed that HPV vaccination in periconceptional period or during pregnancy did not increase the risks of spontaneous abortion (RR = 1.152, 95% CI: 0.909-1.460, 95% PI: 0.442-3.000), birth defects (RR = 1.171, 95% CI: 0.802-1.709, 95% PI: 0.320-4.342), stillbirth (RR = 1.053, 95% CI: 0.616-1.800, 95% PI: 0.318-3.540), preterm birth (RR = 0.940, 95% CI: 0.670-1.318) and ectopic pregnancy (RR = 0.807, 95% CI: 0.353-1.842, 95% PI: 0.128-5.335). In cohort studies, periconceptional or pregnancy exposures of HPV vaccine were not associated with the increased risk of spontaneous abortion (RR = 0.987, 95% CI: 0.854-1.140, 95% PI: 0.652-1.493), birth defects (RR = 0.960, 95% CI: 0.697-1.322, 95% PI: 0.371-2.480), stillbirth (RR = 1.033, 95% CI: 0.651-1.639, 95% PI: 0.052-21.064), small size for gestational age (SGA) (RR = 0.971, 95% CI: 0.873-1.081, 95% PI: 0.657-1.462) and preterm birth (RR = 0.977, 95% CI: 0.874-1.092, 95% PI: 0.651-1.444). Conclusion: HPV vaccine exposures in periconceptional period or during pregnancy did not increase the risks of adverse pregnancy outcomes, including spontaneous abortion, birth defects, stillbirth, SGA, preterm birth and ectopic pregnancy. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42023399777.

Maternal and infant outcomes following exposure to quadrivalent human papillomavirus vaccine during pregnancy

INTRODUCTION

The Department of Defense encourages service members ≤26 years of age to receive the human papillomavirus (HPV) vaccine. Although this vaccine is not recommended in pregnancy, inadvertent vaccination may occur. The objective of this study was to assess whether active duty US military women who received the quadrivalent HPV vaccine (4vHPV) during pregnancy were at increased risk for adverse maternal or infant outcomes.

METHODS

The study population included active duty US military women aged 17-28 years with at least one pregnancy between 2007 and 2014, and the infants resulting from those pregnancies. Pregnancies, live births, and outcomes were identified using medical codes in administrative medical records. Exposure to 4vHPV during pregnancy was ascertained from personnel immunization records. Multivariable regression models were used to calculate risk estimates and 95% confidence intervals for the maternal outcomes of spontaneous abortion, preeclampsia/eclampsia and preterm labor, and the infant outcomes of preterm birth, birth defects, growth problems in infancy or in utero, and infant sex.

RESULTS

Overall, 90,600 pregnancies and 75,670 singleton infants were identified. Approximately 2% of pregnancies and infants were exposed to 4vHPV during pregnancy. After adjustments, no positive associations were detected between inadvertent exposure to 4vHPV during pregnancy and any adverse pregnancy or infant outcomes.

DISCUSSION

Our findings add to an established body of literature demonstrating the safety of 4vHPV when inadvertently administered during pregnancy. Although 4vHPV is no longer administered in the US, its use continues overseas; therefore, safety studies remain important. Furthermore, such studies can provide reassurance to women inadvertently exposed to nonavalent HPV vaccine (9vHPV) in pregnancy, which protects against four of the same antigens as 4vHPV, since safety of 9vHPV has not yet been established in pregnant women.

Pregnancy Outcomes After Human Papillomavirus Vaccination in Periconceptional Period or During Pregnancy: A Systematic Review and Meta-analysis

Background: National immunization schedules in many countries recommend HPV vaccination for females until the age of 26 years, and thus substantial numbers with reproductive age may be exposed to HPV vaccines. Objective: To assess whether inadvertent HPV vaccine exposures in the periconceptional period or during pregnancy were associated with increased risks for adverse pregnancy outcomes. Search strategy: A search of PubMed, Cochrane Library, China National Knowledge Infrastructure (CNKI), and WanFang databases (until March 31, 2019) was performed. Selection criteria: Studies that assess the risk of adverse pregnancy outcomes in HPV vaccine exposed/unexposed pregnancies were included. The adverse pregnancy outcomes included spontaneous abortion, stillbirth, small for sestational age, preterm birth, and birth defects. Data collection and analysis: The pooled relative risk (RR) was applied for the effect measure of the study. RRs and 95% confidence interval (CI) were measured when the paper did not report the effect. Heterogeneity between studies was assessed using the Cochrane's Q and I² statistics. Main results: Of 374 identified citations, 8 met inclusion criteria. Compared with the unexposed pregnancies, HPV vaccine exposed pregnancies were associated with no higher risk for spontaneous abortion (RR, 0.99 [95% CI, 0.90 to 1.08]); stillbirth (RR, 1.16 [95% CI, 0.71 to 1.90]); small for gestational age (RR, 0.96 [95% CI, 0.86 to 1.07]); preterm birth (RR, 1.04 [95% CI, 0.91 to 1.18]); or birth defects (RR, 1.18 [95% CI, 0.97 to 1.43]). Conclusions: Inadvertent bivalent/quadrivalent HPV vaccination during pregnancy was not associated with significantly greater risks of adverse pregnancy outcomes.

Risk of Spontaneous Abortion After Inadvertent Human Papillomavirus Vaccination in Pregnancy

OBJECTIVE

To evaluate the risk of spontaneous abortion after quadrivalent human papillomavirus (4vHPV) vaccination before and during pregnancy across seven integrated health systems within the Vaccine Safety Datalink.

METHODS

Within a retrospective observational cohort, we compared risks for spontaneous abortion after 4vHPV in three exposure windows: distal (16-22 weeks before the last menstrual period [LMP]), peripregnancy (within 6 weeks before the LMP), and during pregnancy (LMP through 19 weeks of gestation). Women 12-27 years of age with a pregnancy between 2008 and 2014, with continuous insurance enrollment 8 months before and through pregnancy end, and with a live birth, stillbirth, or spontaneous abortion were included. Pregnancies were identified through validated algorithms. Spontaneous abortions and stillbirths were verified by chart review with spontaneous abortions adjudicated by clinical experts. We excluded multiple gestations, spontaneous abortions before 6 weeks of gestation, and women using medications increasing risk of spontaneous abortion. Spontaneous abortion risk after 4vHPV during pregnancy was compared with distal vaccination using time-dependent covariate Cox models. Spontaneous abortion risk for peripregnancy compared with distal vaccination was evaluated with standard Cox models.

RESULTS

We identified 2,800 pregnancies with 4vHPV exposure in specified risk windows: 919 (33%) distal, 986 (35%) peripregnancy, and 895 (32%) during pregnancy. Mean age was 22.4 years in distal and peripregnancy groups compared with 21.4 years among women vaccinated during pregnancy. Among women with distal 4vHPV exposure, 96 (10.4%) experienced a spontaneous abortion. For peripregnancy and during pregnancy exposures, spontaneous abortions occurred in 110 (11.2%) and 77 (8.6%), respectively. The risk of spontaneous abortion was not increased among women who received 4vHPV during pregnancy (adjusted hazard ratio 1.10, 95% CI 0.81-1.51) or peripregnancy 1.07 (0.81-1.41).

CONCLUSION

Inadvertent 4vHPV exposure during or peripregnancy was not significantly associated with an increased risk of spontaneous abortion.

Prophylactic vaccination against human papillomaviruses to prevent cervical cancer and its precursors

BACKGROUND

Persistent infection with high-risk human papillomaviruses (hrHPV) types is causally linked with the development of cervical precancer and cancer. HPV types 16 and 18 cause approximately 70% of cervical cancers worldwide.

OBJECTIVES

To evaluate the harms and protection of prophylactic human papillomaviruses (HPV) vaccines against cervical precancer and HPV16/18 infection in adolescent girls and women.

SEARCH METHODS

We searched MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL) and Embase (June 2017) for reports on effects from trials. We searched trial registries and company results' registers to identify unpublished data for mortality and serious adverse events.

SELECTION CRITERIA

Randomised controlled trials comparing efficacy and safety in females offered HPV vaccines with placebo (vaccine adjuvants or another control vaccine).

DATA COLLECTION AND ANALYSIS

We used Cochrane methodology and GRADE to rate the certainty of evidence for protection against cervical precancer (cervical intraepithelial neoplasia grade 2 and above [CIN2+], CIN grade 3 and above [CIN3+], and adenocarcinoma-in-situ [AIS]), and for harms. We distinguished between the effects of vaccines by participants' baseline HPV DNA status. The outcomes were precancer associated with vaccine HPV types and precancer irrespective of HPV type. Results are presented as risks in control and vaccination groups and risk ratios (RR) with 95% confidence intervals in brackets.

MAIN RESULTS

We included 26 trials (73,428 participants). Ten trials, with follow-up of 1.3 to 8 years, addressed protection against CIN/AIS. Vaccine safety was evaluated over a period of 6 months to 7 years in 23 studies. Studies were not large enough or of sufficient duration to evaluate cervical cancer outcomes. All but one of the trials was funded by the vaccine manufacturers. We judged most included trials to be at low risk of bias. Studies involved monovalent (N = 1), bivalent (N = 18), and quadrivalent vaccines (N = 7). Most women were under 26 years of age. Three trials recruited women aged 25 and over. We summarize the effects of vaccines in participants who had at least one immunisation.Efficacy endpoints by initial HPV DNA statushrHPV negativeHPV vaccines reduce CIN2+, CIN3+, AIS associated with HPV16/18 compared with placebo in adolescent girls and women aged 15 to 26. There is high-certainty evidence that vaccines lower CIN2+ from 164 to 2/10,000 (RR 0.01 (0 to 0.05)) and CIN3+ from 70 to 0/10,000 (RR 0.01 (0.00 to 0.10). There is moderate-certainty evidence that vaccines reduce the risk of AIS from 9 to 0/10,000 (RR 0.10 (0.01 to 0.82).HPV vaccines reduce the risk of any CIN2+ from 287 to 106/10,000 (RR 0.37 (0.25 to 0.55), high certainty) and probably reduce any AIS lesions from 10 to 0/10,000 (RR 0.1 (0.01 to 0.76), moderate certainty). The size of reduction in CIN3+ with vaccines differed between bivalent and quadrivalent vaccines (bivalent: RR 0.08 (0.03 to 0.23), high certainty; quadrivalent: RR 0.54 (0.36 to 0.82), moderate certainty). Data in older women were not available for this comparison.HPV16/18 negativeIn those aged 15 to 26 years, vaccines reduce CIN2+ associated with HPV16/18 from 113 to 6 /10,000 (RR 0.05 (0.03 to 0.10). In women 24 years or older the absolute and relative reduction in the risk of these lesions is smaller (from 45 to 14/10,000, (RR 0.30 (0.11 to 0.81), moderate certainty). HPV vaccines reduce the risk of CIN3+ and AIS associated with HPV16/18 in younger women (RR 0.05 (0.02 to 0.14), high certainty and RR 0.09 (0.01 to 0.72), moderate certainty, respectively). No trials in older women have measured these outcomes.Vaccines reduce any CIN2+ from 231 to 95/10,000, (RR 0.41 (0.32 to 0.52)) in younger women. No data are reported for more severe lesions.Regardless of HPV DNA statusIn younger women HPV vaccines reduce the risk of CIN2+ associated with HPV16/18 from 341 to 157/10,000 (RR 0.46 (0.37 to 0.57), high certainty). Similar reductions in risk were observed for CIN3+ associated with HPV16/18 (high certainty). The number of women with AIS associated with HPV16/18 is reduced from 14 to 5/10,000 with HPV vaccines (high certainty).HPV vaccines reduce any CIN2+ from 559 to 391/10,000 (RR 0.70 (0.58 to 0.85, high certainty) and any AIS from 17 to 5/10,000 (RR 0.32 (0.15 to 0.67), high certainty). The reduction in any CIN3+ differed by vaccine type (bivalent vaccine: RR 0.55 (0.43 to 0.71) and quadrivalent vaccine: RR 0.81 (0.69 to 0.96)).In women vaccinated at 24 to 45 years of age, there is moderate-certainty evidence that the risks of CIN2+ associated with HPV16/18 and any CIN2+ are similar between vaccinated and unvaccinated women (RR 0.74 (0.52 to 1.05) and RR 1.04 (0.83 to 1.30) respectively). No data are reported in this age group for CIN3+ or AIS.Adverse effectsThe risk of serious adverse events is similar between control and HPV vaccines in women of all ages (669 versus 656/10,000, RR 0.98 (0.92 to 1.05), high certainty). Mortality was 11/10,000 in control groups compared with 14/10,000 (9 to 22) with HPV vaccine (RR 1.29 [0.85 to 1.98]; low certainty). The number of deaths was low overall but there is a higher number of deaths in older women. No pattern in the cause or timing of death has been established.Pregnancy outcomesAmong those who became pregnant during the studies, we did not find an increased risk of miscarriage (1618 versus 1424/10,000, RR 0.88 (0.68 to 1.14), high certainty) or termination (931 versus 838/10,000 RR 0.90 (0.80 to 1.02), high certainty). The effects on congenital abnormalities and stillbirths are uncertain (RR 1.22 (0.88 to 1.69), moderate certainty and (RR 1.12 (0.68 to 1.83), moderate certainty, respectively).

AUTHORS' CONCLUSIONS

There is high-certainty evidence that HPV vaccines protect against cervical precancer in adolescent girls and young women aged 15 to 26. The effect is higher for lesions associated with HPV16/18 than for lesions irrespective of HPV type. The effect is greater in those who are negative for hrHPV or HPV16/18 DNA at enrolment than those unselected for HPV DNA status. There is moderate-certainty evidence that HPV vaccines reduce CIN2+ in older women who are HPV16/18 negative, but not when they are unselected by HPV DNA status.We did not find an increased risk of serious adverse effects. Although the number of deaths is low overall, there were more deaths among women older than 25 years who received the vaccine. The deaths reported in the studies have been judged not to be related to the vaccine. Increased risk of adverse pregnancy outcomes after HPV vaccination cannot be excluded, although the risk of miscarriage and termination are similar between trial arms. Long-term of follow-up is needed to monitor the impact on cervical cancer, occurrence of rare harms and pregnancy outcomes.

Postlicensure safety surveillance of congenital anomaly and miscarriage among pregnancies exposed to quadrivalent human papillomavirus vaccine

Limited safety data are available on inadvertent exposure to quadrivalent human papillomavirus vaccine (4vHPV) during pregnancy. We conducted a descriptive observational postlicensure safety surveillance study in Kaiser Permanente Southern California and Northern California to assess congenital anomaly and miscarriage among pregnancies exposed to 4vHPV. Using electronic medical records, we identified women who received a dose of 4vHPV between August 2006 and March 2008 within 30 days preconception or any time during a possible pregnancy. A broad algorithm was developed using diagnostic and procedure codes and laboratory tests to identify pregnancy, congenital anomalies, and miscarriages. Medical records of all potential congenital anomaly cases and a random sample of 100 potential miscarriage cases were reviewed to confirm pregnancy exposure and diagnosis. Results were reviewed by an independent Safety Review Committee (SRC). Among the population of 189,629 females who received at least one dose of 4vHPV during the study period, 2,678 females were identified as possibly having a 4vHPV-exposed pregnancy. Among 170 potential congenital anomalies identified, 44 (26%) were found to be both 4vHPV-exposed and confirmed congenital anomaly cases. Among the 633 potential miscarriages identified, the records of a random sample of 100 cases were reviewed, and 9 cases (9%) were confirmed as 4vHPV-exposed miscarriages. The SRC noted no safety signal for congenital anomaly or miscarriage associated with 4vHPV exposure during pregnancy. The rate of major congenital anomaly (3.6%) was in the range of background estimates from the literature. There was no apparent pattern of timing of 4vHPV exposure among 4vHPV-exposed miscarriages.

Human papillomavirus first and second generation vaccines-current status and future directions

It has been more than 10 years that the first prophylactic papillomavirus vaccine became available, although distribution has been mainly limited to the more affluent countries. The first two vaccines have been a great success, hundreds of millions of women and a much smaller number of men have been vaccinated ever since. In a few countries with high vaccination coverage, in particular Australia but also parts of Great Britain and others, clinical impact of vaccination programs is already visible and there are indications for herd immunity as well. Vaccine efficacy is higher than originally estimated and the vaccines have an excellent safety profile. Gardasil9 is a second generation HPV virus-like particle vaccine that was licensed in 2015 and there are more to come in the near future. Currently, burning questions in respect to HPV vaccination are the duration of protection - especially in regard to cross-protection - reduction of the three-dose regimen and its impact on cross-protection; and duration of response, as well as protection against oropharyngeal HPV infections. Furthermore, researchers are seeking to overcome limitations of the VLP vaccines, namely low thermal stability, cost, invasive administration, limited coverage of non-vaccine HPV types, and lack of therapeutic efficacy. In this review we summarize the current status of licensed VLP vaccines and address questions related to second and third generation HPV vaccines.

Commentary on "Maternal immunization: clinical experiences, challenges, and opportunities in vaccine acceptance"

Immunization during pregnancy is an important and effective public health strategy. Obstetrician-gynecologists should start thinking of themselves as vaccinators and develop systems approaches to facilitate vaccination for women both during and outside of pregnancy. The importance of a strong provider recommendation is key.

Prophylactic papillomavirus vaccines

Human papillomaviruses (HPV) are the causative agents of cervical cancer, the third most common cancer in women. The development of prophylactic HPV vaccines Gardasil® and Cervarix® targeting the major oncogenic HPV types is now the frontline of cervical cancer prevention. Both vaccines have been proven to be highly effective and safe although there are still open questions about their target population, cross-protection, and long-term efficacy. The main limitation for a worldwide implementation of Gardasil® and Cervarix® is their high cost. To develop more affordable vaccines research groups are concentrated in new formulations with different antigens including capsomeres, the minor capsid protein L2 and DNA. In this article we describe the vaccines' impact on HPV-associated disease, the main open questions about the marketed vaccines, and current efforts for the development of second-generation vaccines.

A review of methods for detect human Papillomavirus infection

Human Papillomavirus (HPV) is the most common sexually transmitted virus. Worldwide, the most common high-risk (HR)-HPV are -16/18, and approximately 70% of cervical cancers (CC) are due to infection by these genotypes. Persistent infection by HR-HPV is a necessary but not sufficient cause of this cancer, which develops over a long period through precursor lesions, which can be detected by cytological screening. Although this screening has decreased the incidence of CC, HPV-related cervical disease, including premalignant and malignant lesions, continues to be a major burden on health-care systems. Although not completely elucidated, the HPV-driven molecular mechanisms underlying the development of cervical lesions have provided a number of potential biomarkers for both diagnostic and prognostic use in the clinical management of women with HPV-related cervical disease, and these biomarkers can also be used to increase the positive predictive value of current screening methods. In addition, they can provide insights into the biology of HPV-induced cancer and thus lead to the development of nonsurgical therapies. Considering the importance of detecting HPV and related biomarkers, a variety of methods are being developed for these purposes. This review summarizes current knowledge of detection methods for HPV, and related biomarkers that can be used to discriminate lesions with a high risk of progression to CC.

Prevalence of HPV infection and genotypes in women with normal cervical cytology in the state of Paraná, Brazil

OBJECTIVE

We investigated the prevalence of the human Papillomavirus (HPV) and its genotypes in women with normal cervical cytology in the state of Paraná, Brazil, and also epidemiological characteristics.

METHODS

The enrolled patients were seen at six primary health-care units in Paiçandú City, Paraná. Through polymerase chain reaction (PCR) and PCR-RFLP (restriction fragment length polymorphism) techniques, 40 HPV genotypes were found, including 15 high risk, 3 undetermined risk and 22 low risk. Socio-demographic characteristics and sexual behavior were also recorded by interviews based on a structured questionnaire completed at the time of enrollment.

RESULTS

Among 418 patients examined, HPV was detected in 6.7 %, mainly in women aged <25 years. The overall prevalence of high-risk, low-risk and undetermined-risk HPV types was 42.9, 45.7, and 11.7 %, respectively. HPV-16 was the most common type detected (14.3 %), followed by types 66 (11.4 %) and 31 and 70 (8.6 % each). Detection of HPV DNA was positively associated with the number of sexual partners within the previous 12 months (p < 0.031; OR = 5.4; CI = 0.98-29.8).

CONCLUSION

When considering the lack of studies in Paraná on women with normal cytology, the results of this study will improve estimates of HPV DNA populations, and provide baseline values against which the impact of vaccination can be assessed in the future.