Are all vaccines safe for the pregnant traveller? A systematic review and meta-analysis

Efficacy of vaccination during pregnancy in reducing the risk of SARS-CoV-2 infection in infants younger than 12 months. Puglia (Italy), 2021-23

This retrospective cohort study evaluated the effectiveness of maternal vaccination against COVID-19 in reducing the risk of SARS-CoV-2 infection in infants younger than 12 months. The study, conducted at the "Policlinico" University Hospital of Bari, included 3346 newborns and their mothers. The study explored the degree of protection offered by maternal vaccination depending on the timing, type, and trimester of vaccination, also taking into account the mother's history of infection. We compared the incidence rate of infection between children of vaccinated and unvaccinated mothers; the values were 10.2% and 18.1%, respectively, and the difference was statistically significant. The overall effectiveness of the vaccine against the infection was 45%. Further analysis revealed increasing efficacy as the doses of vaccine administered to the mother increased and in case of a previous history of maternal infection. Dual immune stimulation (vaccination and natural infection) was 83% effective in preventing infection among newborns. The multivariable models confirmed the protective effect of vaccination with all types of vaccines used. The analysis of infection's incidence in newborns revealed an interesting temporal trend, with increasing incidence with time, suggesting a possible correlation with the persistence of maternal antibodies or with the gradual weaning. The results on the protective capacity of vaccines are in line with the global literature. Strengths of study include sample size, robust methodology, and multivariate analyses. Institutions could intensify awareness campaigns to encourage both pregnant women and all those who would like to become pregnant to receive SARS-CoV-2 vaccination.

Interventions to increase vaccination against COVID-19, influenza and pertussis during pregnancy: a systematic review and meta-analysis

BACKGROUND

Pregnant women and their babies face significant risks from three vaccine-preventable diseases: COVID-19, influenza and pertussis. However, despite these vaccines' proven safety and effectiveness, uptake during pregnancy remains low.

METHODS

We conducted a systematic review (PROSPERO CRD42023399488; January 2012-December 2022 following PRISMA guidelines) of interventions to increase COVID-19/influenza/pertussis vaccination in pregnancy. We searched nine databases, including grey literature. Two independent investigators extracted data; discrepancies were resolved by consensus. Meta-analyses were conducted using random-effects models to estimate pooled effect sizes. Heterogeneity was assessed using the I2 statistics.

RESULTS

From 2681 articles, we identified 39 relevant studies (n = 168 262 participants) across nine countries. Fifteen studies (39%) were randomized controlled trials (RCTs); the remainder were observational cohort, quality-improvement or cross-sectional studies. The quality of 18% (7/39) was strong. Pooled results of interventions to increase influenza vaccine uptake (18 effect estimates from 12 RCTs) showed the interventions were effective but had a small effect (risk ratio = 1.07, 95% CI 1.03, 1.13). However, pooled results of interventions to increase pertussis vaccine uptake (10 effect estimates from six RCTs) showed no clear benefit (risk ratio = 0.98, 95% CI 0.94, 1.03). There were no relevant RCTs for COVID-19. Interventions addressed the 'three Ps': patient-, provider- and policy-level strategies. At the patient level, clear recommendations from healthcare professionals backed by text reminders/written information were strongly associated with increased vaccine uptake, especially tailored face-to-face interventions, which addressed women's concerns, dispelled myths and highlighted benefits. Provider-level interventions included educating healthcare professionals about vaccines' safety and effectiveness and reminders to offer vaccinations routinely. Policy-level interventions included financial incentives, mandatory vaccination data fields in electronic health records and ensuring easy availability of vaccinations.

CONCLUSIONS

Interventions had a small effect on increasing influenza vaccination. Training healthcare providers to promote vaccinations during pregnancy is crucial and could be enhanced by utilizing mobile health technologies.

Safety of COVID-19 vaccines during pregnancy: A systematic review and meta-analysis

Background

Assessment of COVID-19 vaccines safety during pregnancy is urgently needed.

Methods

We conducted a systematic review and meta-analysis to evaluate the safety of COVID-19 vaccines, including their components and technological platforms used in other vaccines during pregnancy and animal studies to complement direct evidence. We searched literature databases from its inception to September 2021 without language restriction, COVID-19 vaccine websites, and reference lists of other systematic reviews and the included studies. Pairs of reviewers independently selected, data extracted, and assessed the risk of bias of the studies. Discrepancies were resolved by consensus. (PROSPERO CRD42021234185).

Results

We retrieved 8,837 records from the literature search; 71 studies were included, involving 17,719,495 pregnant persons and 389 pregnant animals. Most studies (94%) were conducted in high-income countries, were cohort studies (51%), and 15% were classified as high risk of bias. We identified nine COVID-19 vaccine studies, seven involving 309,164 pregnant persons, mostly exposed to mRNA vaccines. Among non-COVID-19 vaccines, the most frequent exposures were AS03 and aluminum-based adjuvants.

A meta-analysis of studies that adjusted for potential confounders showed no association with adverse outcomes, regardless of the vaccine or the trimester of vaccination.

Neither the reported rates of adverse pregnancy outcomes nor reactogenicity exceeded expected background rates, which was the case for ASO3- or aluminum-adjuvanted non-COVID-19 vaccines in the proportion meta-analyses of uncontrolled studies/arms. The only exception was postpartum hemorrhage after COVID-19 vaccination (10.40%; 95% CI: 6.49-15.10%), reported by two studies; however, the comparison with non-exposed pregnant persons, available for one study, found non-statistically significant differences (adjusted OR 1.09; 95% CI 0.56-2.12). Animal studies showed consistent results with studies in pregnant persons.

Conclusion

We found no safety concerns for currently administered COVID-19 vaccines during pregnancy. Additional experimental and real-world evidence could enhance vaccination coverage. Robust safety data for non-mRNA-based COVID-19 vaccines are still needed.

Safety of measles, rubella and mumps vaccines in adults: a prospective cohort study

BACKGROUND

In recent years, multiple outbreaks of measles associated with vaccine hesitancy occurred in high-income countries, where measles incidence had previously been low. Most safety data about the measles, mumps and rubella (MMR) vaccine are derived from studies conducted among children, whereas evidence regarding the safety profile of the vaccine in adults is scarce.

METHODS

In 2017, during an outbreak of measles in Europe, Israeli travellers to high-risk locations who were incompletely vaccinated, were urged to complete the two MMR vaccination schedule before their travel. In this prospective cohort study, we analysed adverse events (AEs) of MMR and MMRV (measles, mumps, rubella and varicella) vaccines among these travellers. All participants were followed up using structured questionnaires 2-4 weeks after vaccination.

RESULTS

Seven hundred and eighty-five adult travellers whose median age was 49.2 years were vaccinated and followed up. Any AEs were reported by 25.2% of all participants; 11.6% reported local AEs, and 18.6% reported systemic AEs, none of which were severe. In general, AEs were much more common among female travellers (19.4% of males vs 30.1% of females (P < 0.001)). Local AEs, overall systemic AEs, headache and arthralgia were much more common among females, whereas rates of general malaise and fever were not statistically different between genders. We did not observe any significant differences in the rates of total, local or systemic AEs between the MMR and MMRV vaccines. Higher rates of systemic AEs were observed among participants who were younger and probably immunized once with MMR compared to older vaccines immunized once to measles only and to those who were never immunized.

CONCLUSIONS

The current study demonstrated low rates of systemic AEs and no serious AEs following either MMR or MMRV administration. More AEs were reported among females, and rates of AEs were similar after either MMR or MMRV.

Safety of components and platforms of COVID-19 vaccines considered for use in pregnancy: A rapid review

BACKGROUND

Rapid assessment of COVID-19 vaccine safety during pregnancy is urgently needed.

METHODS

We conducted a rapid systematic review, to evaluate the safety of COVID-19 vaccines selected by the COVID-19 Vaccines Global Access-Maternal Immunization Working Group in August 2020, including their components and their technological platforms used in other vaccines for pregnant persons. We searched literature databases, COVID-19 vaccine pregnancy registries, and explored reference lists from the inception date to February 2021 without language restriction. Pairs of reviewers independently selected studies through COVIDENCE, and performed the data extraction and the risk of bias assessment. Discrepancies were resolved by consensus. Registered on PROSPERO (CRD42021234185).

RESULTS

We retrieved 6757 records and 12 COVID-19 pregnancy registries from the search strategy; 38 clinical and non-clinical studies (involving 2,398,855 pregnant persons and 56 pregnant animals) were included. Most studies (89%) were conducted in high-income countries and were cohort studies (57%). Most studies (76%) compared vaccine exposures with no exposure during the three trimesters of pregnancy. The most frequent exposure was to AS03 adjuvant, in the context of A/H1N1 pandemic influenza vaccines, (n = 24) and aluminum-based adjuvants (n = 11). Only one study reported exposure to messenger RNA in lipid nanoparticles COVID-19 vaccines. Except for one preliminary report about A/H1N1 influenza vaccination (adjuvant AS03), corrected by the authors in a more thorough analysis, all studies concluded that there were no safety concerns.

CONCLUSION

This rapid review found no evidence of pregnancy-associated safety concerns of COVID-19 vaccines or of their components or platforms when used in other vaccines. However, the need for further data on several vaccine platforms and components is warranted, given their novelty. Our findings support current WHO guidelines recommending that pregnant persons may consider receiving COVID-19 vaccines, particularly if they are at high risk of exposure or have comorbidities that enhance the risk of severe disease.

Safety of COVID-19 vaccines, their components or their platforms for pregnant women: A rapid review

BACKGROUND

Pregnant women with COVID-19 are at an increased risk of severe COVID-19 illness as well as adverse pregnancy and birth outcomes. Many countries are vaccinating or considering vaccinating pregnant women with limited available data about the safety of this strategy. Early identification of safety concerns of COVID-19 vaccines, including their components, or their technological platforms is therefore urgently needed.

METHODS

We conducted a rapid systematic review, as the first phase of an ongoing full systematic review, to evaluate the safety of COVID-19 vaccines in pregnant women, including their components, and their technological platforms (whole virus, protein, viral vector or nucleic acid) used in other vaccines, following the Cochrane methods and the PRISMA statement for reporting (PROSPERO-CRD42021234185).We searched literature databases, COVID-19 and pregnancy registries from inception February 2021 without time or language restriction and explored the reference lists of relevant systematic reviews retrieved. We selected studies of any methodological design that included at least 50 pregnant women or pregnant animals exposed to the vaccines that were selected for review by the COVAX MIWG in August 2020 or their components or platforms included in the COVID-19 vaccines, and evaluated adverse events during pregnancy and the neonatal period.Pairs of reviewers independently selected studies through the COVIDENCE web software and performed the data extraction through a previously piloted online extraction form. Discrepancies were resolved by consensus.

RESULTS

We identified 6768 records, 256 potentially eligible studies were assessed by full-text, and 37 clinical and non-clinical studies (38 reports, involving 2,397,715 pregnant women and 56 pregnant animals) and 12 pregnancy registries were included.Most studies (89%) were conducted in high-income countries. The most frequent study design was cohort studies (n=21), followed by surveillance studies, randomized controlled trials, and registry analyses. Most studies (76%) allowed comparisons between vaccinated and unvaccinated pregnant women (n=25) or animals (n=3) and reported exposures during the three trimesters of pregnancy.The most frequent exposure was to AS03 adjuvant in the context of A/H1N1 pandemic influenza vaccines (n=24), followed by aluminum-based adjuvants (n=11). Aluminum phosphate was used in Respiratory Syncytial Virus Fusion candidate vaccines (n=3) and Tdap vaccines (n=3). Different aluminum-based adjuvants were used in hepatitis vaccines. The replication-deficient simian adenovirus ChAdOx1 was used for a Rift Valley fever vaccine. Only one study reported exposure to messenger RNA (mRNA) COVID-19 vaccines that also used lipid nanoparticles. Except for one preliminary report about A/H1N1 influenza vaccination (adjuvant AS03) - corrected by the authors in a more thorough analysis, all studies concluded that there were no safety concerns.

CONCLUSION

This rapid review found no evidence of pregnancy-associated safety concerns of COVID-19 vaccines that were selected for review by the COVAX MIWG or of their components or platforms when used in other vaccines. However, the need for further data on several vaccine platforms and components is warranted given their novelty. Our findings support current WHO guidelines recommending that pregnant women may consider receiving COVID-19 vaccines, particularly if they are at high risk of exposure or have comorbidities that enhance the risk of severe disease.

Healthy, safe and responsible: the modern female traveller

One-half of all travellers are women; yet, there is a distinct lack of detailed travel health knowledge on topics of unique relevance to women. While there is medical advice relating to stages in the female lifecycle, it neglects women-specific practical aspects despite their ability to harm travellers’ health and cause inconvenience. This paper discusses comprehensively three major aspects of travel as they relate to women. First, it suggests the management of personal hygiene, bodily functions, menstruation and sexual behaviour, and alerts to the limited knowledge on travel mental health issues.

Second, apart from travelling in a female body with its specific demands, being a woman requires special attention to safety and security. Within various travel contexts, women have many opportunities for minimising potential risks.

Finally, guided by travel medicine’s acknowledgment of its role in the concept of responsible travel, this article goes beyond the usual general statements and broad advice and offers detailed and practical suggestions on how the female traveller can contribute to the overall goal of minimising any potential harm to fellow humans and the natural environment. Recognising the scarcity of women-specific travel information, pathways to better education, and a range of suggestions for urgent research facilitate the provision of high-quality travel health care tailored specifically to women’s needs.

Viral Hepatitis in pregnancy

The global prevalence of viral hepatitis is very high and seems to be rising over the years. The infection can profoundly affect pregnant women causing significant maternal and perinatal morbidity and mortality with some strains much worse than others. Hepatitis A (HAV) and E (HEV) which are transmitted mainly through the faecal-oral route present as acute hepatitis during pregnancy and are responsible for most local epidemic outbreaks. HAV infection remains self-limiting during pregnancy, while HEV has a higher prevalence and causes significant morbidity. It is also associated with a very high maternal mortality rate (20 %) and requires special attention in endemic areas. HEV vaccines do exist, but the WHO has yet to approve them for general use. Hepatitis B is the most prevalent form and is part of the ante-natal screening program. The presence of HBeAg is associated with high viral loads and infectivity. Antiviral therapy, preferably tenofovir (TDF), is recommended for mothers with viral load ≥ 200,000 IU/mL₂), with the neonates receiving both active and passive immunisations. Hepatitis C and D are usually found as chronic infections in the pregnant and non-pregnant populations. Screening for hepatitis C during pregnancy and its subsequent management is still unsettled, but the introduction of direct-acting antiviral (DAA) drugs will change the picture if their safety is established in pregnancy. HDV is an incomplete virus linked to HBV and cannot establish an infection on its own. Controlling HBV is paramount to controlling HDV. HEV is quite prevalent and looked upon as hepatotropic. It seems to be quite prevalent in some blood donor populations and has a high co-infection rate with HCV. It has a high Mother-to-Child-Transmission (MTCT) but causes little or no illness in infected infants, and antenatal screening is not justified. This review summarises the prevalence, clinical picture, maternal, perinatal effects, and the management and prevention of hepatitis A, B, C, D, E and G viral infections during pregnancy.

A clinician's perspective on yellow fever vaccine-associated neurotropic disease

Yellow fever (YF) causes high fever, liver dysfunction, renal failure, hypercoagulopathy and platelet dysfunction and can lead to shock and death with a case-fatality ratio of 20-50%. YF vaccination results in long-lasting protective immunity. Serious adverse events (SAEs), such as YF vaccine-associated neurotropic disease (YEL-AND) are rare. We present a case of a 56-year-old Caucasian man with fever, headache, cognitive problems at the emergency department. He received a primary YF vaccination 4 weeks prior to symptom onset. Cerebrospinal fluid tested positive (POS) for YF virus by reverse transcriptase polymerase chain reaction and confirmed diagnosis of YEL-AND. The patient recovered with symptomatic treatment. We reviewed published clinical reports on YEL-AND indexed for MEDLINE. We identified and analyzed 53 case reports. Forty-five patients were male and eight were female. Twenty-nine cases met criteria for definite YEL-AND and twenty-four for suspected YEL-AND according to YF Vaccine Safety Working Group. We applied the Brighton Collaboration diagnostic criteria to assess the diagnostic accuracy of the clinical diagnoses and found meningoencephalitis in 38 reported YEL-AND cases, Guillain Barré Syndrome (GBS) in seven, Acute Disseminated Encephalomyelitis (ADEM) in six and myelitis in five. Thirty-five patients recovered or improved; however, not all cases had a complete follow-up. The prognosis of YEL-AND presenting with GBS, ADEM or myelitis was poor. Fourteen patients received therapy (corticosteroids, intravenous immunoglobulins and/or plasmapheresis). In conclusion, YF vaccine-associated neurotropic disease is a very rare but SAE after YF vaccination. We described a case of YEL-AND and propose a standardized clinical workup of this condition based on a review of the literature. Centralized registration of complications of YF vaccination is encouraged.

Japanese encephalitis vaccination in pregnancy among U.S. active duty military women

INTRODUCTION

Japanese encephalitis (JE) vaccine is an inactivated vaccine that has shown no risks in pregnancy in animal models, but epidemiologic studies are lacking. U.S. military service members located in JE endemic regions are required to be vaccinated; understanding the potential adverse events (AEs), including AEs that may occur in pregnancy, is needed. Here, we assessed pregnancy and infant health outcomes in association with JE vaccination in pregnancy.

METHODS

The study population consisted of 192,570 pregnancies to active duty women (2003-2014), captured in the Department of Defense Birth and Infant Health Research program. JE vaccine in pregnancy, vaccine count, formulation, trimester, and whether first career dose coincided with pregnancy were compared with unexposed pregnancies to assess risk of pregnancy and infant health outcomes. Adjusted risk estimates and 95% confidence intervals (CIs) were calculated by multivariable models.

RESULTS

Of the 192,570 identifed pregnancies, 513 were exposed to the JE vaccine; 474 exposures occurred in the first trimester. For all outcomes, elevated risk estimates ranging from 1.53 to 1.70, were observed with receipt of >1 JE vaccine in pregnancy, though 95% CIs were wide and encompassed the null. First dose of JE vaccination in pregnancy was associated with a 1.87 (95% CI: 1.12-3.13) times increased risk of low birthweight (LBW) when excluding pregnancies exposed to other non-routinely recommended vaccinations in pregnancy. All other associations were null in both main and subset analyses.

CONCLUSIONS

The overall results of these analyses provide reassuring findings for the safety of JE vaccination in pregnancy. Higher counts of JE vaccine received in pregnancy yielded large yet non-statistically significant risk estimates for all outcomes, though likely driven by lack of pregnancy awareness. An association was observed with LBW in subset analyses, but it was limited to women receiving their first JE vaccine and not observed in the larger main analyses.