Pregnant women are vulnerable to many communicable and non- communicable diseases; either the susceptibility to or severity of infections increases due to pregnancy. Vaccination programmes are one of the most important and cost effective health interventions. Fear of adverse effects makes clinicians and mothers hesitant to vaccinate in pregnancy and the obstetrician is only attuned to administering tetanus toxoid (TT); this article addresses the recent recommendations for vaccination of pregnant and postpartum women with Td (tetanus and diphtheria), Tdap (Tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine), influenza and other vaccines.
General guidelines for vaccination of pregnant women include evaluation for the possibility of pregnancy before immunization and immunization history. As a rule, live viral vaccines are contraindicated during pregnancy; however this risk is largely theoretical. The benefits of vaccinating pregnant women are usually greater than the potential risks when the possibility of exposure to that particular infection is high, when the infection would possibly harm the mother or fetus or when the vaccine is unlikely to harm them. Inactivated viral vaccines, bacterial vaccines and toxoids are safe in pregnancy. Women who have inadvertently received live vaccine during pregnancy should not be counseled to terminate the pregnancy for teratogenic risk; however non pregnant women who have received live vaccine should delay pregnancy for at least 4 weeks. This is a change from the previous recommendation of avoidance of pregnancy for 3 months. Another important point of intervention is the postpartum period, where breast feeding women can be immunized safely.
Both tetanus and diphtheria toxoids (Td) and TT vaccines have been used extensively in pregnant women worldwide to prevent neonatal tetanus; their administration has not been shown to be teratogenic. Current recommendation is that everyone should be given a booster shot for tetanus and diphtheria every 10 years after first being immunized; hence Td during pregnancy has replaced TT in many parts of the world.
Pertussis is a highly contagious respiratory infection caused by Bordetella pertussis which colonises respiratory tract mucous membranes, produces toxins that damage mucosa and induce systemic effects; the typical spasms of coughing ending with a “whoop”. Both the incidence and mortality are underestimated and underreported. Older individuals, especially parents, represent a reservoir of infection transmitting disease to unvaccinated or partially vaccinated infants. Despite generally high coverage with childhood pertussis vaccines, it is one of the leading causes of deaths worldwide. In recent years, a decrease in diphtheria– pertussis–tetanus (DPT) vaccine compliance has been reported from different parts of
“Cocooning” is the strategy of vaccinating parents, siblings, grandparents, and health workers who are likely to have close contact with an infant aged <12 months. These contacts, especially pregnant women in the later part of pregnancy or immediately postpartum should receive Tdap to reduce the risk for transmission of pertussis to infants, ideally at least 2 weeks prior to the anticipated contact. Tdap is a combination vaccine that contains tetanus (T), diphtheria (d) and acellular pertussis (ap) in a single injection, and provides protection against all three; it is approved for adolescents from the age of 11 (younger contacts should receive DTaP) and adults ages 19 to 64. There is no live vaccine component in Tdap. Some studies have suggested that maternal antibodies to pertussis can inhibit production of active pertussis-specific antibody after administration of DTaP vaccine to infants of mothers vaccinated with Tdap during pregnancy, referred to as “blunting”. However, the benefit of protection given by maternal antibodies in newborn infants is much higher than the risk of shifting the burden of the disease to later in infancy.
It is recommended to give one dose of Tdap during each pregnancy irrespective of the patient’s prior history of receiving Tdap. Although Tdap may be given at any time during pregnancy, the ideal time for administration is between 27 and 36 weeks’ of gestation, which maximizes the maternal antibody response and transfer of antibodies to the neonate. The first dose of TT should be replaced with Td and the second, with Tdap. If Tdap is not administered during pregnancy, it should be administered soon after delivery. Along with several international agencies like Advisory Committee on Immunization Practices (ACIP) of CDC,
of Pediatricians (IAP) in their 2013 guidelines also strongly recommend Tdap to
pregnant women. Indian Academy
Influenza is a highly contagious acute respiratory illness caused by infection with influenza viruses (Orthomyxoviridae) which affects the upper and lower respiratory tracts and produces systemic signs and symptoms. Three types, Influenza A, B and C are determined by nuclear material. Influenza A subtypes are further divided based on H and N surface glycoproteins.
“Flu” is often mistaken for the common cold, but has serious and far reaching complications. Global pandemics and epidemics cause a huge disease burden; though pregnancy does not increase susceptibility to influenza infection, pregnant women in the second and third trimesters of pregnancy are at increased risk for hospitalization, severe illness, serious complications like pneumonia and death. Maternal influenza infection has also been associated with an increased risk of schizophrenia (which is higher with first trimester exposure) in the offspring. There is also an increased risk of preeclampsia in mothers and preterm labor, low birth weight, lower Apgar scores at birth and stillbirth. It is critical to vaccinate against influenza before the season begins; however this cannot be predicted accurately due to geographical and other variations. Hence routine influenza vaccination is recommended for all women who are or will be pregnant (in any trimester) during influenza season. In case of outbreaks of influenza prior to the season, vaccination should be given to all pregnant women. A single dose of the trivalent inactivated vaccine (TIV) intramuscularly is recommended; the live attenuated nasal spray is contraindicated in pregnancy. Immunization to the mother affords protection to the infant for at least the first 6 months of life. ACOG guidelines state that “preventing influenza during pregnancy is an essential element of prenatal care, and the most effective strategy for preventing influenza is annual immunization”. This is endorsed by many other agencies including WHO, ACIP (CDC) and Indian Association of Physicians (API).
Hepatitis B poses a serious risk to infants at birth and universal screening with HBsAg for all pregnant women is recommended. Pregnant women who are considered as being at risk of developing HBV infection during pregnancy (more than one sex partner during the preceding 6 months, evaluated or treated for an STI, recent or current intravenous drug abuse, or an HBsAg-positive sex partner) should be tested with antibody to surface antigen (anti –HBs) and be vaccinated if negative. Vaccination should be given only if clearly needed and possible advantages outweigh the possible risks. There are limited data which suggest that developing fetuses are not at risk for adverse events following hepatitis B vaccine. Babies should get HBIG at birth and first dose of vaccine within 12 hours of life.
HPV vaccines are not recommended for use in pregnant women. If a woman gets pregnant after initiating the vaccination series, no intervention is needed but the remainder of the 3-dose series should be delayed until completion of pregnancy.
The puerperal period is an excellent opportunity for vaccination and promotion of positive health advice. It is safe for a woman to receive routine vaccines after birth and in the lactation period. A woman who has not received Tdap or influenza vaccine should be vaccinated right after delivery and a woman who is not immune to measles, mumps and rubella and/or varicella (chicken pox) should be vaccinated before she leaves the hospital. HPV vaccine is also safe during the lactation period.In conclusion, maternal vaccination is a cost-effective and targeted strategy to improve pregnancy outcomes in developed and developing countries. Many national organizations like IAP, Indian Association of Physicians (API) and FOGSI, and all international public health agencies recommend vaccination during pregnancy for influenza and Tdap. Lack of awareness of benefits and concerns about vaccine safety in pregnancy are common barriers to vaccination. The real challenge is to educate health professionals and make these vaccinations routine.