Tdap Vaccine
1] What is the Tdap Vaccine ?
The Tdap vaccine is a combination vaccine which offers triple protection against three bacterial infections – Tetanus , Diphtheria and Pertussis in a single shot .The three vaccine components are tetanus (T), diphtheria (d) and acellular pertussis (ap). ‘T’ refers to standard dose of tetanus antigen , whereas the lowercase letters ‘d ’ and ‘p’ are used to indicate a reduced dose of diphtheria and pertussis antigens compared to the pediatric vaccine (DTaP).
2] How is the Tdap vaccine different from the TT/Td vaccine which is generally given during pregnancy ?
Tetanus toxoid (TT) /Tetanus and Diphtheria toxoid (Td) vaccines help protect the newborn and young infants only against tetanus and diphtheria. The Tdap vaccine additionally provides protection against pertussis through transplacental transfer of antibodies from mother to foetus. Since 2011 , various bodies Like ACIP and ACOG have been recommending a single dose of Tdap vaccine during pregnancy.In India , FOGSI has recommended the use of Tdap vaccine during pregnancy since 2014.
3] What is pertussis ?
Pertussis is a highly contagious respiratory infection caused by the Gram – negative bacteroium Bordetella pertussis. It is more commonly known as ‘whooping cough’ Pertussis is transmitted through airborne droplets or direct contact with nasopharyngeal discharge from an infected person. It affects people of all ages but newborns are at a higher risk of infection and serious complication like hospitalization pneumonia, seizures and even death.
4] What is the incidence of Pertussis in India ?
India ranks no – 1 globally with – 24000 pertussis cases reported by WHO in 2017. However , pertussis continues to be an under diagnosed disease and under reported disease. It is estimated that for each reported case of pertussis, 83 more infections may go undetected.
5] Why are newborns at a higher risk of neonatal pertussis ?
In India, newborn infants do not begin their primary vaccination series against pertussis with DTP vaccines until at least 6 weeks of age. This leaves the newborns vulnerable to contract serious pertussis infections from family members and especially mothers. Mothers have been identified as the source of infection in – 37 % of neonatal pertussis case and are the most common source of pertussis infection for newborn infants.
6] Why is Tdap vaccination recommended during pregnancy ?
Tdap vaccination during pregnancy is one of the most cost – effective strategies in protecting the newborn /young infants from neonatal pertussis. Tdap vaccine when administered during pregnancy results in transplacental transfer of antibodies from mother to foetus. These antibodies offer protection during first few months of life when newborns are most vulnerable to disease and its complications.
7] When is the optimal time during pregnancy to administer Tdap vaccine ?
Recent data supports that the optimal time to vaccinate with Tdap vaccine is during 27-36 weeks of gestation because higher antibody concentrations are likely to be achieved in the foetus. These protective antibodies that are transferred to the foetus protect the newborn until they begin their own DTP vaccination series. Several global and local authorities like ACOG , RCOG and IAP recommend single dose of Tdap uaccine during 27 – 36 weeks of gestation.
8] Is it necessary to vaccinate pregnant women with Tdap during every pregnancy even if she has been vaccinated in the past ?
In October 2012, a critical new data on the lack of persistence of maternal pertussis antibodies was reviewed by ACIP and it was found that there was rapid waning of antibody levels 2-3 years post vaccination. This indicated that maternal antibodies generated from the Tdap vaccine during one pregnancy would not be sufficient to provide protection to the newborn during subsequent pregnancies Both ACIP and ACOG recommend that all pregnant women receive single dose of Tdap vaccine during each pregnancy preferably during 27-36 weeks of gestation.
9] Can the Tdap vaccine be recommended to pregnant women who have received TT vaccination in the same pregnancy ?
Tdap vaccination can be considered instead of the second dose of tetanus toxoid. A prospective study involving healthy Thai pregnant women (370 enrolled in year April 2015 – September 2016), were offered Tdap between 26-36 weeks of gestation. Of the 370 , ninety – eight women received at least one extra dose of tetanus – containing vaccine during this current pregnancy (1 dose in 37 women, 2 doses in 60 women, 3 doses in 1 woman).
No reported increase in the severity or duration of adverse events associated with the administration of an extra tetanus – containing vaccine was observed.
10] Can Tdap and Influenza vaccines be given to pregnant women in the same visit ?
In a retrospective study , 36 , 844 pregnant women were administered with Tdap and Flu vaccines concomitantly in 8,464 (23%) and sequentially in 28, 380 (77%) pregnancies. No statistically significant increased risk of fever or any medically attended adverse effect was found when Flu and Tdap were co – administered during pregnancy.
11] How many countries recommend Tdap vaccination during pregnancy ?
Tdap vaccination during pregnancy has been recommended by global authorities like ACIP & ACOG since 2011. As of March 2018, > 35 countries recommend Tdap vaccination during pregnancy. This includes countries Like UK, USA , Canada , Spain , Australia and New Zealand. In India , FOGSI has recommended the use of Tdap vaccine during pregnancy since 2014.
12] What is the safety data available with Tdap ?
Evidence supports the favorable safety profile of Tdap when administered during the 3 trimester of pregnancy. Safety data from a prospective observational study where Tdap was administered to pregnant women during the third trimester (793 pregnancy outcomes) as well as data from passive surveillance where pregnant women were exposed to Boostrix in the 3rd and 2nd trimester have shown o vaccine related adverse effect on pregnancy or on the health of the foetus /newborn Child.
Recommendations for Tdap vaccination during pregnancy
ACIP,2012 : Women are recommended to receive a single dose of Tdap during each pregnancy, which should be administered from 27- 36 weeks of gestation, regardless of previous receipt of Tdap.
RCOG,2012 : Women are recommended to receive a dose to Tdap during each pregnancy, which should be administered from 27 through 36 weeks gestation, regardless of previous receipt of Tdap.
IAP,2013 : One dose of Tdap vaccine to pregnant mothers/adolescents durning each pregnancy (preferred durning 27 through 36 weeks gestation) regardless of number of years from prior Td or Tdap vaccination.
WHO, 2015 : Vaccination of pregnant women is likely to be one of the most cost – effective additional strategies for preventing disease in infants too young to be vaccinated.
FOGSI, 2016 : Tdap should be administered during pregnancy in order to provide optimal protection to the baby during its first months of life – strength of recommendation”A”.
ACOG,2017 : Administer Tdap vaccine to all pregnant women as early as 27- 36 weeks.
