Vaccination of pregnant women against co …

Some reminders about whooping cough and its prevention with vaccination

Whooping cough is a highly contagious infection of the respiratory tract. This disease is serious, sometimes fatal, in children. There is an effective vaccination, but it cannot be started before the age of 8 weeks; before three months, vaccinated children are only partially protected by vaccination. In France, over 90% of pertussis deaths occur in infants and children under the age of six months. Parents (especially the mother) and siblings are the main sources of contamination of children. Vaccination of those around you (“cocooning”) is one way to protect them, but this recommendation is not sufficiently enforced.

Vaccines against whooping cough

The list of pertussis vaccines can be viewed here; the vaccines available in France are all combined with other vaccines, in particular against diphtheria and tetanus, or the polio vaccine, Haemophilus influenzae type b or hepatitis B. A distinction is made between pediatric formulations, containing a full or standard dose of antigen and used in particular for the primary vaccination of infants, and formulations containing a reduced dose of antigen, used for booster in infants. , adolescents and adults, the reduced antigen content reduces the risk of local inflammatory reaction.

The content of these combination vaccines is represented by valences designated by the following abbreviations:

  • D: standard dose of diphtheria toxoid;
  • d: reduced dose of diphtheria toxoid;
  • T: tetanus toxoid (regardless of the amount of antigen);
  • P: trivalent vaccine (poliovirus 1, 2 and 3) inactivated against poliomyelitis;
  • Ca: standard dose of acellular pertussis vaccine (as opposed to the inactivated whole vaccine, currently no longer used in France);
  • ca: reduced dose of acellular pertussis vaccine.

In France, the only formulation available for vaccinating adults (the one containing reduced doses of antigen) is quadrivalent, designated by the abbreviation “dTcaP” (diphtheria-tetanus-pertussis-polio). There are two commercial vaccines corresponding to the dTcaP vaccine: the BOOSTRIXTETRA vaccine and the REPEVAX vaccine.

In other European countries and in the United States there is a combined trivalent form “dTP” or “Tdap” in English (for Tetanus-diphtheria-acellular pertussis), available under different brands (ADACEL, BOOSTAGEN, BOOTRIX, COVAXIS, TDAPBOOSTER, TRIAXIS).

New recommendation: vaccination of pregnant women

Published data on immunogenicity support a satisfactory immune response in pregnant women. Pertussis antibodies are transferred to the fetus via the placenta, allowing protection of the newborn and the child who is too young to be vaccinated.

For vaccines against pertussis and diphtheria, an inhibitory effect of maternal antibodies on the production of antibodies by the infant’s immune system, called the “blunting” effect, has been described. However, this effect has virtually no impact on the protection against pertussis and diphtheria of subsequently vaccinated children.

Data on the real-life efficacy of vaccination of pregnant women have confirmed its efficacy, with a reduction in the number of cases, the number of hospitalizations and mortality from pertussis in children between the ages of zero and two months. Compared to vaccinating relatives, vaccination during pregnancy showed better real-life vaccine efficacy to protect the baby before one’s own vaccination.

The High Authority for Health (HAS) therefore recommends vaccinate pregnant women against whooping cough from the second trimester of pregnancy, favoring the period between 20 and 36 weeks of amenorrhea (i.e. between the beginning of the 5And month and the end of 8And month of pregnancy). This strategy allows to increase the passive transplacental transfer of maternal antibodies against pertussis and to ensure optimal protection of the newborn.

Pertussis vaccination should be performed during each pregnancyin order to ensure that a sufficient amount of antibodies are passed on to the future newborn.

The following clarifications are made:

  • Vaccination during pregnancy can be done with a trivalent (dTca) or tetravalent (dTcaP: BOOSTRIXTETRA or REPEVAX) vaccine, depending on availability (trivalent dTca vaccines are currently not available in France);
  • In any case, a minimum delay of one month compared to the last dTP vaccine (REVAXIS) must be respected;
  • Vaccination against pertussis can be done at the same time as vaccination against seasonal flu or covid 19; however, while vaccination against pertussis should preferably be carried out during the second or third trimester of pregnancy, vaccinations against covid 19 and influenza should be carried out as early as possible during pregnancy;
  • when the mother has been vaccinated during pregnancy and at least one month has elapsed between vaccination and delivery, it is no longer necessary to vaccinate those close to the baby.

In the absence of vaccination of pregnant women during pregnancy, vaccination is recommended :

  • For the mother immediately after delivery (immediately after delivery)before leaving the maternity ward, even if you are breastfeeding, according to the current strategy for cocoon.
  • For those around the newborn (parents, brothers, sisters, grandparents and other people who may be in close and lasting contact with the future baby during its first six months) no later than the birth of the baby, in accordance with previous recommendations.

This new recommendation has been integrated into MesVaccins’ vaccine decision support system and electronic vaccination registry (Figure 1).

Figure 1 : Viewing personalized vaccination recommendations in the MesVaccins.net electronic vaccination record for a 28-year-old pregnant woman.

Reference


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