Maternal Immunization During Pregnancy: Influenza and Pertussis
Pregnancy changes the immune, cardiovascular, and respiratory systems in ways that can increase the severity of certain infections. Influenza and pertussis are especially important in perinatal medicine because maternal illness may threaten the pregnant patient, while infection around birth can place a newborn at serious risk. Vaccination during pregnancy offers a way to protect both patients and infants during a period of heightened vulnerability.
Maternal immunization is also a public health intervention. Antibodies produced after vaccination cross the placenta, giving infants temporary protection before they are old enough to complete their own routine vaccination schedules. This passive immunity is particularly valuable during the first weeks of life, when exposure to respiratory pathogens can lead to hospitalization.
The scientific discussions associated with FAOPS 2020 and PREBIC AA 2020 reflected the importance of coordinated perinatal care, neonatal prevention, and evidence-based practice. Although the Tokyo congress was canceled in April 2020 because of the COVID-19 pandemic and international travel difficulties, its central themes remain relevant to clinicians, researchers, and health systems.
Why Pregnancy Changes Infection Risk
Influenza can become more severe during pregnancy because the heart and lungs work harder, oxygen demands rise, and immune responses adapt to support fetal development. A pregnant patient with influenza may face increased risks of pneumonia, hospitalization, intensive care, preterm birth, and other complications. The severity of disease varies by season, circulating strain, underlying conditions, and access to prompt treatment.
Pertussis, commonly called whooping cough, presents a different concern. Adults may experience a prolonged cough without the dramatic symptoms seen in infants, yet they can transmit Bordetella pertussis to a newborn. Young infants have immature airways and limited immune defenses, making them vulnerable to apnea, pneumonia, feeding problems, seizures, and death.
Maternal vaccination should therefore be considered part of routine antenatal prevention rather than an optional service offered only during outbreaks. Counseling is most effective when it begins early, is repeated at appropriate visits, and addresses the patient’s specific concerns about safety, timing, and vaccine ingredients.
Influenza Vaccination In Antenatal Care
The inactivated influenza vaccine is recommended during pregnancy in many national immunization programs and can be administered during any trimester when indicated. It cannot cause influenza because it does not contain live replicating virus. Seasonal vaccination is important because influenza strains change and immunity declines over time.
Protection benefits both members of the maternal-infant pair. Vaccination lowers the pregnant patient’s risk of severe influenza, and transferred antibodies can reduce influenza illness in the infant during the first months after birth. The degree of protection varies with vaccine match, maternal immune response, timing, and the level of influenza circulation in the community.
Live attenuated intranasal influenza vaccines are generally avoided during pregnancy. If a patient received such a vaccine before recognizing the pregnancy, the event is not usually considered a reason to terminate the pregnancy, but it should be documented and reviewed according to local guidance. Clinical teams should distinguish between a vaccine contraindication and a situation requiring specialist assessment.
Early antiviral treatment remains important when influenza is suspected during pregnancy. Vaccination does not eliminate every infection, and a patient with fever, cough, shortness of breath, or worsening systemic symptoms needs timely evaluation. Treatment decisions should follow current public health and obstetric protocols rather than waiting for laboratory confirmation when clinical suspicion is high.
Pertussis Prevention Before Birth
A tetanus, diphtheria, and acellular pertussis vaccine, commonly called Tdap, is administered during each pregnancy in many guidelines, often between 27 and 36 weeks of gestation. The preferred timing allows the pregnant patient to develop antibodies and transfer them across the placenta before delivery. Local recommendations may differ, particularly when pertussis activity is elevated or an earlier dose is needed.
Vaccination during every pregnancy is advised because antibody levels decline over time and each newborn requires protection. A dose received in a previous pregnancy may not provide enough antibodies for a later infant. Even when a patient has received Tdap before, the current pregnancy presents a new opportunity to protect the baby during the early neonatal period.
If delivery is imminent, vaccination can still be worthwhile, although the infant may receive less passive antibody protection because antibody transfer requires time. Vaccination after birth protects the parent from future infection but does not provide the same prenatal antibody transfer. Household members and caregivers should also be up to date, creating a protective “cocoon” around the newborn while recognizing that cocooning cannot replace maternal vaccination.
Clear communication is essential. Patients may worry that the vaccine could cause pertussis or harm fetal development. Clinicians can explain that Tdap uses acellular pertussis components, does not contain live Bordetella pertussis, and has been studied extensively in pregnancy. A calm discussion of expected local reactions, fever management, contraindications, and benefits supports informed acceptance.
Comparing Influenza And Pertussis Protection
The two vaccines address different pathogens and operate within different seasonal and epidemiological patterns. Influenza immunization is generally repeated each season because circulating viruses evolve. Pertussis vaccination during pregnancy is generally repeated with each pregnancy to optimize antibody transfer for each newborn.
| Consideration | Influenza Vaccine | Tdap Vaccine |
|---|---|---|
| Main target | Seasonal influenza viruses | Pertussis, tetanus, and diphtheria |
| Typical pregnancy timing | Any trimester when indicated | Commonly 27–36 weeks, based on local guidance |
| Main maternal benefit | Reduced risk of severe influenza and complications | Reduced risk of pertussis and transmission to the infant |
| Main newborn benefit | Transferred antibodies during early infancy | Strong early protection against severe pertussis |
| Usual schedule | Seasonal or annually updated vaccination | Usually during every pregnancy |
| Important clinical point | Treat suspected influenza promptly | Vaccinate even if Tdap was given in a prior pregnancy |
This comparison should support, rather than replace, individualized clinical assessment. Vaccine schedules can vary by country, product availability, pregnancy history, outbreak conditions, and public health policy. Perinatal teams should use current national recommendations and record the product, date, gestational age, and any adverse reaction.
Reliable immunization systems also depend on communication between obstetric, midwifery, primary care, pediatric, and pharmacy teams. Broader discussions about resilient perinatal systems emphasize why vaccination delivery must remain dependable during emergencies, staffing shortages, and disruptions to routine services.
Safety, Counseling, And Equity
Available evidence supports the safety of recommended inactivated influenza and Tdap vaccines during pregnancy. Expected reactions are usually mild, such as soreness at the injection site, fatigue, headache, or a low-grade fever. Severe allergic reactions are rare. A history of a serious allergic reaction to a previous dose or vaccine component requires careful evaluation before another dose.
Counseling should acknowledge uncertainty without overstating risk. Patients deserve practical information about what is known, what symptoms to expect, when to seek urgent care, and why vaccination is recommended. The conversation should also make room for cultural values, previous experiences with health services, concerns about fetal safety, and misinformation encountered online.
Access is a major determinant of vaccine uptake. Missed prenatal appointments, cost, transportation, language barriers, limited clinic hours, and fragmented records can all reduce coverage. Offering vaccination during antenatal visits, documenting status in shared records, using interpreters, and providing written information in accessible language can improve completion.
The same equity lens applies to patients living with HIV, chronic respiratory disease, diabetes, or other conditions that may increase infection risk. Perinatal HIV care has demonstrated how much progress depends on consistent prevention, treatment, and follow-up; discussions of perinatal HIV achievements provide a useful reminder that coordinated care can change outcomes across generations.
Making Immunization Routine
A maternity service can integrate immunization into standard workflows rather than relying on individual memory. At the first prenatal assessment, staff can review prior vaccination, explain the recommended schedule, and identify contraindications. Electronic prompts, standing orders, and nurse-led administration can reduce delays. The record should follow the patient across antenatal, birth, and pediatric services.
Clinicians should also prepare for conversations after a declined vaccine. A refusal is an opportunity to revisit concerns at a later appointment, provide balanced information, and avoid judgmental language. Some patients accept vaccination later when they receive consistent advice from a trusted midwife, obstetrician, family physician, or pediatric clinician.
Hospitals can monitor coverage by trimester, vaccine type, missed opportunities, and reasons for non-vaccination. Reviewing these measures helps teams identify whether the main problem is hesitancy, supply, documentation, scheduling, or referral failure. Quality improvement is strongest when data are linked to practical changes in service delivery.
Practical Actions For Perinatal Teams
- Offer seasonal influenza vaccination as soon as it is available and indicated during pregnancy.
- Schedule Tdap at the recommended gestational age for every pregnancy, using local policy.
- Record vaccination clearly and share the information with newborn and primary care teams.
- Train staff to discuss benefits, expected reactions, contraindications, and common misconceptions.
- Extend education and vaccination access to partners, household members, and regular caregivers.
Research Priorities And Global Collaboration
Research continues to examine the durability of transferred antibodies, the effect of timing on neonatal protection, vaccine performance during different influenza seasons, and the best approaches for patients with complex medical conditions. Studies also assess how maternal vaccination affects preterm infants, populations with limited antenatal care, and communities facing unequal access to preventive services.
Surveillance is essential because influenza viruses change and pertussis transmission can rise unexpectedly. Linking maternal vaccination records with neonatal outcomes, laboratory data, hospital admissions, and adverse event monitoring can improve recommendations. International collaboration adds value by comparing programs across different health systems and identifying strategies that work in both high-resource and resource-constrained settings.
Professional meetings and scientific networks help translate this evidence into practice. The FAOPS 2020 congress site documented a planned forum for perinatal and neonatal medicine, including scientific sessions, speakers, abstracts, and collaboration across Asian and Oceanian societies. The cancellation of the meeting did not lessen the need for shared learning; it highlighted the importance of adaptable communication channels for maternal and newborn health.
Maternal vaccination works best when it is treated as a continuous part of perinatal care. Protecting the pregnant patient, transferring antibodies to the newborn, reducing household transmission, and maintaining reliable clinical systems are connected goals. Health professionals can strengthen these goals by making influenza and pertussis immunization visible, timely, accessible, and easy to discuss at every stage of pregnancy. Use current national guidance, build vaccination into routine antenatal workflows, and ensure every eligible patient receives a clear opportunity to protect both herself and her baby.
