Influenza and pregnancy: a review of the literature from India

Factors influencing vaccine acceptance in pregnancy during the COVID-19 pandemic: A multicenter study from West Bengal, India

Influenza, COVID-19, tetanus, pertussis and hepatitis B pose increased risk for pregnant women and infants and could be mitigated by maternal immunization. In India Tetanus-diphtheria (Td) and COVID-19 vaccines are recommended during pregnancy, while influenza and tetanus-acellular pertussis-diphtheria (Tdap) vaccines are not. We conducted a multicenter study from November 2021 to June 2022 among pregnant women (n = 172) attending antenatal clinics in three public hospitals in West Bengal, to understand the factors that influence women's decisions to get vaccinated during pregnancy. Questions assessed vaccination coverage, knowledge, intention and willingness to pay for influenza vaccine, and factors influencing decisions to get Td, influenza, and COVID-19 vaccines. 152/172 (88.4%) women were vaccinated with Td, 159/172 (93%) with COVID-19, 1/172 (0.6%) with influenza, and none with Tdap. 10/168 (6%) had received hepatitis B vaccine (HBV). Community health workers advice was crucial for Td uptake and, the belief of protection from COVID for COVID-19 vaccines. Most women were unaware about Tdap (96%), influenza (75%), and influenza severity during pregnancy and infancy (85%). None were advised for influenza vaccination by healthcare providers (HCP), albeit, 93% expressed willingness to take, and pay INR 100-300 (95% CI: ≤100 to 300-500) [$ 1.3-4.0 (95% CI: ≤1.3, 4-6.7)] for it. Vaccination on flexible dates and time, HCP's recommendation, proximity to vaccination center, and husband's support were most important for their vaccination decisions. Women were generally vaccine acceptors and had high uptake of vaccines included in the Universal Immunization Program (UIP). Inclusion of influenza, Tdap, and HBV into UIP may improve maternal vaccine uptake.

Maternal Seroprevalence and Placental Transfer of COVID-19 Antibodies in Pregnancy: A Hospital-Based Study

BACKGROUND

Coronavirus disease 2019 (COVID-19) is a relatively new disease with high morbidity and mortality. Information about the prevalence of infections in pregnancy could help identify herd immunity, project epidemics, and decide policy guidelines.

OBJECTIVES

The aim of this study was to determine the infection susceptibility risk of COVID-19 in pregnancy, to determine the prevalence of COVID-19 antibodies (IgG & IgM), and to evaluate the determinants of COVID-19 antibody positivity in pregnancy.

MATERIALS AND METHODS

This was an analytical cross-sectional study involving 258 consenting pregnant women recruited at Irrua Specialist Teaching Hospital, Edo State, Nigeria. Of these, 179 participants were recruited from the antenatal clinic, and 79 from the gynecology emergency unit. A structured questionnaire was administered at baseline. Venous blood was obtained at enrolment to test for total antibodies using ELISA. A nasopharyngeal swab was simultaneously obtained for COVID-19 PCR for all participants. Umbilical cord blood was taken after delivery in those who had positive serology. Socio-demographic variables and clinical presentation of respondents were considered as exposure variables, and this was cross-tabulated with outcome variables in bivariate analysis using chi-square with a level of significance at a P-value less than 0.05. Variables in bivariate analysis of chi-square that have a P-value less than 0.2 were entered into a logistic regression using multivariate logistic models.

RESULTS

 The study detected active COVID-19 infections among 7.4% (19/258) of the study participants. The study demonstrated a seroprevalence of COVID-19 antibodies in 62.4% (161/258) of the participants at recruitment and showed a strong correlation between working in the healthcare setting and living in an urban environment. Our study also reported 5.3% (8/152) of cord blood antibody positivity among study participants. The concentration of maternal immunoglobulin strongly and positively correlated with cord blood seropositivity.

CONCLUSION

Prevalence estimates are an underestimate of the actual proportion of pregnant women with prior COVID-19 exposure as observed in the study discrepancy of confirmed PCR infection and evidence of previous infection from serology. The study also highlighted a low efficiency of placental transfer of COVID-19 antibodies at birth among those who were seropositive at baseline and showed that maternal antibody levels play an important role in determining the efficiency of placenta transfer of COVID-19 antibodies in pregnancy.

Determinants of maternal influenza vaccination in the context of low- and middle-income countries: A systematic review

BACKGROUND

Pregnancy and early infancy are considered to be the vulnerable phases for severe influenza infection causing morbidity and mortality. Despite WHO recommendations, influenza is not included in the immunization programs of many low- and middle-income countries. This systematic review is aimed at identifying barriers and facilitators for maternal influenza vaccination amongst the perinatal women and their health care providers in low- and middle-income countries.

METHODS

We selected 11 studies from the 1669 records identified from PubMed, CABI, EMBASE and Global Health databases. Studies related to both pandemic and routine influenza vaccination and studies conducted amongst women in the antenatal as well as postnatal period were included. Both qualitative, quantitative, cross-sectional and interventional studies were included.

RESULTS

Knowledge about influenza disease, perception of the disease severity during pregnancy and risk to the foetus/newborn and perceived benefits of influenza vaccination during pregnancy were associated with increased uptake of influenza vaccination during pregnancy. Recommendation by health care provider, vaccination in previous pregnancy and availability of vaccine in public health system facilitated vaccine uptake. High parity, higher education, vaccination in the later months of pregnancy, less than 4 antenatal visits, concerns about vaccine safety and negative publicity in media were identified as barriers for influenza vaccination. Lack of government recommendation, concerns about safety and effectiveness and distrust in manufacturer were the barriers for the healthcare providers to recommend vaccination.

CONCLUSION

While availability of influenza vaccine in public health system can be a key to the success of vaccine implementation program, increasing the awareness about need and benefits of maternal influenza vaccination amongst pregnant women as well as their health care providers is crucial to improve the acceptance of maternal influenza vaccination in low and middle-income countries.

Differential impact of COVID-19 in pregnant women from high-income countries and low- to middle-income countries: A systematic review and meta-analysis

BACKGROUND

SARS-CoV-2 has infected a large number of pregnant women.

OBJECTIVE

To compare clinical, perinatal outcomes of women with COVID-19 from high-income countries (HICs) and low- to middle-income countries (LMICs).

SEARCH STRATEGY

Online databases were searched.

SELECTION CRITERIA

Original studies on pregnant women with COVID-19 were included.

DATA COLLECTION AND ANALYSIS

Information on clinical presentation, co-morbidities, pregnancy outcomes, neonatal outcomes, and SARS-CoV-2 infection in neonates was extracted.

MAIN RESULTS

The pooled estimate of SARS-CoV-2 positive neonates is 3.7%. Symptomatic presentations are less common in LMICs compared to HICs (odds ratio [OR] 0.38). Diabetes (OR 0.5), hypertension (OR 0.5), and asthma (OR 0.14) are commonly reported from HICs; hypothyroidism (OR 2.2), anemia (OR 3.2), and co-infections (OR 6.0) are commonly reported in LMICs. The overall risk of adverse pregnancy outcomes is higher in LMICs compared to HICs (OR 2.4). Abortion (OR 6.2), stillbirths (OR 2.0), and maternal death (OR 7.8) are more common in LMICs. Preterm births and premature rupture of membranes are comparable in both groups. Neonatal deaths (OR 3.7), pneumonia (OR 7.5), and neonatal SARS-CoV-2 infection (OR 1.8) are commonly reported in LMICs.

CONCLUSIONS

In LMICs, pregnant women and neonates are more vulnerable to adverse outcomes due to COVID-19. PROSPERO registration no: CRD42020198743.

Maternal immunization: trends in South and Southeast Asian countries

Maternal immunization has the potential to reduce neonatal deaths caused by vaccine-preventable infectious diseases. Elimination of maternal and neonatal tetanus from many countries illustrates the potential benefits of maternal immunization as a strategy to decrease neonatal mortality caused by vaccine-preventable infections. Many countries in South and Southeast Asia have high cases of neonatal deaths, which were historically attributed to vaccine-preventable infections. Still, these countries vary in recommendations regarding immunization of pregnant women. We reviewed the current recommendations for the use of tetanus toxoid, tetanus-diphtheria, or tetanus-diphtheria-acellular pertussis (Tdap) vaccines for immunization of pregnant women. In addition to protection against tetanus and diphtheria, administration of the Tdap vaccine to pregnant women could help protect neonates against pertussis until they can receive the first two vaccine doses of their primary course. Vaccination against seasonal influenza is also recommended in many countries worldwide for pregnant women as influenza can pose health risks for the mother-fetus unit and the infant. Despite the recognized benefit of influenza vaccination for pregnant women, only some South and Southeast Asian countries have implemented its recommendation. The success of maternal tetanus vaccination has kindled the interest in vaccines that can be safely administered during pregnancy. Future availability of vaccines against respiratory syncytial virus and group B streptococcus, for use in pregnant women, could help prevent neonatal infections, especially in regions where diseases are less controlled. Communicating the body of evidence that supports maternal immunization to obstetricians is key for achieving optimal vaccination coverage to ensure protection of neonates. The current review aims to create awareness about the existing and potential benefits of maternal immunization in South and Southeast Asia.

Expert opinion on the way forward for improving maternal influenza vaccination in India

INTRODUCTION

: Rates of maternal vaccination against influenza are extremely low in India. An expert panel of obstetric-gynecologists and pediatricians met to develop consensus-based recommendations for improving awareness of the benefits of influenza vaccination during pregnancy in India.

AREAS COVERED

: The group discussed experiences of influenza infection in pregnancy and infancy before focusing on maternal vaccination practices in India, including the degree of communication between obstetric-gynecologists and pediatricians and opinions on optimal timing for vaccination. The impact of inconsistent vaccine prescription practices by healthcare providers was discussed, as well as current clinical recommendations on maternal influenza vaccination.

EXPERT OPINION

: Although clinical evidence demonstrates the benefit of maternal influenza vaccination in any trimester, influenza vaccination is not widely accepted in India as an integral part of antenatal care. There is a lack of familiarity among obstetricians of clinical guidelines on maternal influenza vaccination. This can be addressed with an education campaign targeting obstetricians and other providers of maternal healthcare. With variable influenza seasons between regions in India, common vaccine stock shortages, and data suggesting influenza vaccination is feasible anytime in pregnancy, all opportunities to offer vaccination to this high-risk group for severe influenza disease should be considered.

Maternal and Perinatal Outcomes of Influenza in Pregnancy after Treatment with Oseltamivir

Context:

Influenza infection in pregnancy causes 4%–8% case fatality and five times more perinatal mortality. Influenza is a major contributor to mortality in developing countries; however, the morbidity has largely been underestimated. Public health interventions for prevention are also lacking.

Aims:

This study aimed to determine the seasonality of influenza in pregnant Indian women and to estimate the maternal and perinatal morbidity after treatment with oseltamivir.

Settings and Design:

This was a prospective observational cohort study, conducted in a tertiary hospital.

Subjects and Methods:

Pregnant women with ILI (influenza-like illness) were recruited into Cohort 1 (polymerase chain reaction [PCR] positive) and Cohort 2 (PCR negative). Gestational age-matched asymptomatic controls formed Cohort 3. Women in Cohort 1 received oseltamivir for 5 days. The incidence of small-for-gestational age (SGA) and preterm birth were the primary outcomes. Maternal and neonatal morbidity formed the secondary outcomes.

Statistical Analysis:

Unmatched (Cohort 1 and 2) and matched analysis (Cohort 1 and 3) were done. Student's t-test and Chi-square test were used to compare between variables.

Results:

Year-round incidence of influenza was recorded. Severe illness was more in Cohort 1 compared to Cohort 2 (36.2% vs. 6.3%; P < 0.001). SGA was comparable in all the cohorts (13%). Preterm birth (7.8% vs. 3.3%; P < 0.08; relative risk-2.75) was considerably high in Cohort 1. Secondary maternal and neonatal outcomes were similar between the groups.

Conclusion:

Influenza in pregnancy showed year-round incidence and increased maternal and neonatal morbidity despite treatment with oseltamivir. We suggest the need for newer interventions to curtail the illness in pregnancy.

A Hospital-Based Nonconcurrent Cohort Study on Factors Associated with in-Hospital Mortality in Patients with Laboratory Confirmed Influenza

Background and Aim:

Influenza is a disease with varied clinical presentation and varied mortality reported in existing literature. The study aimed to determine the factors associated with mortality in patients hospitalized with influenza infection.

Materials and Methods:

This was a 5-year nonconcurrent cohort study done in a tertiary care center in Southern India. Patients with laboratory confirmed influenza infection diagnosed between January 2013 and October 2018 were recruited into the study.

Results:

A total of 130 patients were recruited. Diabetes (45.4%) and chronic obstructive pulmonary disease (COPD) (26.1%) were the most common comorbid illnesses. Thirty-one patients (23.8%) required admission to the intensive care unit (ICU) and 58 patients required ventilation (noninvasive/mechanical ventilation [MV] – 44.6%). Influenza A was the most common isolated strain (46.9%). Univariate analysis demonstrated that a high pneumonia severity index (P < 0.0001), CURB 65 > 2 (P < 0.0001), MV dependency (P < 0.0001), need for ICU stay (P < 0.0001), low PF ratio (P < 0.0001), COPD (P = 0.021), secondary bacterial pneumonia (P < 0.0001), acute respiratory distress syndrome (P = 0.0004), and acute kidney injury (P = 0.0006) were the significant factors associated with in-hospital mortality. Multivariate analysis demonstrated that new onset/worsening renal dysfunction was the only factor significantly associated with in-hospital mortality in patients admitted with influenza.

Conclusions:

Our study showed a mortality of 12.3% (n= 16) and new onset/worsening renal dysfunction was the only patient factor associated with mortality. Early recognition of complications and appropriate treatment may reduce mortality in patients admitted with severe influenza. We recommend influenza vaccination for at-risk populations to reduce severity and mortality.

The faces of influenza vaccine recommendation: A Literature review of the determinants and barriers to health providers' recommendation of influenza vaccine in pregnancy

INTRODUCTION

WHO recommends influenza vaccination for pregnant women and health providers (HPs), yet global uptake for both is persistently low. Research suggests that HPs greatly influence uptake of influenza vaccine in pregnant women. Our review studies HPs' recommendation of influenza vaccine to pregnant women, determinants and barriers to recommendation, and the role that HPs may play in global influenza vaccine coverage.

METHODS

We undertook a comprehensive global review of literature relating to HPs' recommendation of seasonal influenza vaccines to pregnant women and the determinants and barriers to recommendation and how this may vary by country and context. We evaluated data from each study including frequency of HP recommendation, vaccine coverage, determinants and barriers to recommendation, and the odds of recommending. We tracked the frequency of determinants and barriers to recommendation in heat maps and organized data by world regions and income classifications.

RESULTS

From 32 studies in 15 countries, we identified 68 determinants or barriers to HPs' recommendation. Recommendation rates were highest (77%) in the Americas and lowest in South East Asia (18%). A HP's own influenza vaccine status was a main determinant of recommendation in multiple country contexts and from different provider types. Financial barriers to recommendation were present in higher-income countries and policy-related barriers were highlighted in lower-income countries. HP perceptions of safety, efficacy, and the utility of vaccine were the most frequently cited barriers, relevant in almost every context.

CONCLUSIONS

HP recommendation is important to influenza vaccine implementation in pregnant women. A HP's own status is an important recommendation determinant in multiple contexts. Vaccine program implementation plans should consider the impact of HPs' knowledge, awareness and vaccine confidence on their own uptake and recommendation practices, as well as on the uptake among pregnant women. Addressing safety and efficacy concerns is relevant in all contexts for HPs and pregnant women.

Influenza vaccine: A viable option to protect pregnant women and infants from seasonal flu: A retrospective hospital-based study in India

BACKGROUND

Influenza is a highly contagious disease with global annual outbreaks of 3-5 million severe cases and 0.25-0.5 million deaths. The risk is greater in pregnant women that results in high morbidity and mortality.

OBJECTIVE

The objective of this study was to see the efficacy of influenza vaccine on pregnant women and their newborn upto 6 months.

METHOD

This was a retrospective study (January 2016-March 2018). Records of 346 pregnant women were included in this study (vaccinated: 288; unvaccinated: 58). Women and infants were categorised into Category A, B or C according to the guidelines issued by the Ministry of Health and Family Welfare, India on influenza.

RESULTS

The groups were comparable with respect to baseline characteristics. Greater number of women received influenza vaccine during the first trimester (n = 117). During the gestation period, majority of the women in the vaccinated group were symptom-free compared with the unvaccinated (92% vs 70.7%). Also, none of the vaccinated women were categorised into category C compared with one who was laboratory tested positive for influenza in the unvaccinated group. Similar results were seen postpartum and more number of infants remained symptom-free in the vaccinated group compared with unvaccinated (69.3% vs 25.9%). More number of infants were born pre-term in the unvaccinated group compared with vaccinated (15.5% vs 8.6%).

CONCLUSIONS

Immunisation with influenza vaccine in any trimester during pregnancy was found to protect the mother and infants upto 6 months of age against seasonal influenza without significant maternal adverse effects. In order to improve vaccination rates, there must be a national vaccination policy and incorporation of maternal immunisation in standard antenatal care.

Influenza vaccination of pregnant women: Engaging clinicians to reduce missed opportunities for vaccination

BACKGROUND

Antenatal influenza vaccination (AIV) is an effective intervention for protecting pregnant women and their newborns against influenza. Although the World Health Organization recommends AIV at any stage of pregnancy, in low- and middle-income countries, including India, it is rarely provided. Research suggests that antenatal care (ANC) provider practices explain much of this limited coverage. Our study in urban Pune, India, assessed the feasibility of a two-stage clinician-engagement strategy to reduce missed opportunities for AIV in urban private-practice ANC clinics.

METHODS

Clinicians were randomized to intervention and control groups in slum and middle-class study sites. Intervention-group clinicians (active clinicians) were assessed on vaccination-related views and practices, and were presented with authoritative AIV recommendations from global, academic and professional medical organizations. In a second meeting after a community survey, findings concerning vaccination-related views and experiences were explained to active clinicians. Assessments of community vaccination views were not provided to control-group clinicians. Both groups maintained logs of ANC clinic visit vaccination status throughout the 11-month study period to enable identification of missed and taken opportunities for vaccination. Analyses were restricted to visits of women in their third trimester without previous AIV in the current pregnancy.

RESULTS

Overall, 30 clinicians participated. After first and second interactions, active clinicians in middle-class communities vaccinated at 12.2% and 37.8%, respectively. Middle-class control clinicians vaccinated at <0.2% throughout the study. This difference in AIV taken opportunities between middle-class active and control clinics was statistically significant (p < 0.05) after first and second interactions. In slum-community sites, active clinicians' AIV activity was minimal throughout.

CONCLUSIONS

Our approach for engaging clinicians effectively reduced missed opportunities for AIV in urban middle-class settings of Pune. It may also improve maternal vaccination for other conditions. The absence of any similar effect in slum-based clinics likely reflects critical limitations of vaccine access.

Human Metapneumovirus and Other Respiratory Viral Infections during Pregnancy and Birth, Nepal

Human metapneumovirus (HMPV) is a respiratory virus that can cause severe lower respiratory tract disease and even death, primarily in young children. The incidence and characteristics of HMPV have not been well described in pregnant women. As part of a trial of maternal influenza immunization in rural southern Nepal, we conducted prospective, longitudinal, home-based active surveillance for febrile respiratory illness during pregnancy through 6 months postpartum. During 2011-2014, HMPV was detected in 55 of 3,693 women (16.4 cases/1,000 person-years). Twenty-five women were infected with HMPV during pregnancy, compared with 98 pregnant women who contracted rhinovirus and 7 who contracted respiratory syncytial virus. Women with HMPV during pregnancy had an increased risk of giving birth to infants who were small for gestational age. An intervention to reduce HMPV febrile respiratory illness in pregnant women may have the potential to decrease risk of adverse birth outcomes in developing countries.

Influenza epidemiology and immunization during pregnancy: Final report of a World Health Organization working group

From 2014 to 2017, the World Health Organization convened a working group to evaluate influenza disease burden and vaccine efficacy to inform estimates of maternal influenza immunization program impact. The group evaluated existing systematic reviews and relevant primary studies, and conducted four new systematic reviews. There was strong evidence that maternal influenza immunization prevented influenza illness in pregnant women and their infants, although data on severe illness prevention were lacking. The limited number of studies reporting influenza incidence in pregnant women and infants under six months had highly variable estimates and underrepresented low- and middle-income countries. The evidence that maternal influenza immunization reduces the risk of adverse birth outcomes was conflicting, and many observational studies were subject to substantial bias. The lack of scientific clarity regarding disease burden or magnitude of vaccine efficacy against severe illness poses challenges for robust estimation of the potential impact of maternal influenza immunization programs.

Report of the WHO technical consultation on the effect of maternal influenza and influenza vaccination on the developing fetus: Montreal, Canada, September 30-October 1, 2015

In 2012, the World Health Organization (WHO) released a position paper on influenza vaccination recommending that pregnant women have the highest priority for seasonal vaccination in countries where the initiation or expansion of influenza immunization programs is under consideration. Although the primary goal of the WHO recommendation is to prevent influenza illness in pregnant women, the potential benefits of maternal immunization in protecting young infants are also recognized. The extent to which maternal influenza vaccination may prevent adverse birth outcomes such as preterm birth or small-for-gestational-age birth, however, is unclear as available studies are in disagreement. To inform WHO about the empirical evidence relating to possible benefits of influenza vaccination on birth outcomes, a consultation of experts was held in Montreal, Canada, September 30-October 1, 2015. Presentations and discussions covered a broad range of issues, including influenza virus infection during pregnancy and its effect on the health of the mother and the fetus, possible biological mechanisms for adverse birth outcomes following maternal influenza illness, evidence on birth outcomes following influenza illness during pregnancy, evidence from both observational studies and randomized controlled trials on birth outcomes following influenza vaccination of pregnant women, and methodological issues. This report provides an overview of the presentations, discussions and conclusions.

Maternal influenza and birth outcomes: systematic review of comparative studies

BACKGROUND

Although pregnant women are considered at high risk for severe influenza disease, comparative studies of maternal influenza and birth outcomes have not been comprehensively summarised.

OBJECTIVE

To review comparative studies evaluating maternal influenza disease and birth outcomes.

SEARCH STRATEGY

We searched bibliographic databases from inception to December 2014.

SELECTION CRITERIA

Studies of preterm birth, small-for-gestational-age (SGA) birth or fetal death, comparing women with and without clinical influenza illness or laboratory-confirmed influenza infection during pregnancy.

DATA COLLECTION AND ANALYSIS

Two reviewers independently abstracted data and assessed study quality.

MAIN RESULTS

Heterogeneity across 16 studies reporting preterm birth precluded meta-analysis. In a subgroup of the highest-quality studies, two reported significantly increased preterm birth (risk ratios (RR) from 2.4 to 4.0) following severe 2009 pandemic H1N1 (pH1N1) influenza illness, whereas those assessing mild-to-moderate pH1N1 or seasonal influenza found no association. Five studies of SGA birth showed no discernible patterns with respect to influenza disease severity (pooled odds ratio 1.24; 95% CI 0.96-1.59). Two fetal death studies were of sufficient quality and size to permit meaningful interpretation. Both reported an increased risk of fetal death following maternal pH1N1 disease (RR 1.9 for mild-to-moderate disease and 4.2 for severe disease).

CONCLUSIONS

Comparative studies of preterm birth, SGA birth and fetal death following maternal influenza disease are limited in number and quality. An association between severe pH1N1 disease and preterm birth and fetal death was reported by several studies; however, these limited data do not permit firm conclusions on the magnitude of any association.

TWEETABLE ABSTRACT

Comparative studies are limited in quality but suggest severe pandemic H1N1 influenza increases preterm birth.

Influenza Illness in Pregnant Indian Women: A Cross-Sectional Study

Data about burden of influenza in pregnancy in India are scant. In order to assess the contribution of influenza to acute respiratory illness (ARI) in pregnancy, 266 north Indian pregnant females with febrile ARI were studied from December 2014 to May 2015. Twin nasopharyngeal/oropharyngeal swabs were obtained and tested for influenza viruses by RT-PCR. Fifty (18.8%) patients tested positive for influenza (A/H1N1pdm09 in 41, A/H3N2 in 8, and influenza B Yamagata in 1). Rigors, headache, and a family history of ARI were significantly more frequent in influenza positive patients. Oseltamivir and supportive therapy were administered to all confirmed cases. Nine influenza positive cases needed hospitalization for their respiratory illness, and 5 developed respiratory failure. Of these, 4 (3 in third trimester) succumbed to their illness. We conclude that influenza viruses are a cause of significant morbidity and mortality among pregnant females with ARI in north India. As such, appropriate preventive strategies of influenza vaccination and early initiation of antiviral therapy during illness are stressed.