Bronchiolitis: mothers must be vaccinated during pregnancy, why this new recommendation?

After Beyfortus, the High Authority for Health validates a new means of preventing bronchiolitis in infants.

From September, subject to the decision on reimbursement by Health Insurance, parents could have the choice between Beyfortus, a preventive treatment (passive immunization) to be administered to the newborn against respiratory syncytial virus infections. , and Abrysvo, a vaccination intended for women in the eighth month of pregnancy.

It obtained European marketing authorization in August 2023. “It is indicated for protection against lower respiratory tract diseases caused by RSV in infants from birth up to 6 months of age, following maternal immunization during pregnancy,” notes the HAS in a press release.

Requested by the Ministry of Health, the HAS followed the European opinion, based on the results of the MATISSE study: a reduction of 81.8% at 3 months and 69.4% at 6 months in infections. severe respiratory illnesses linked to RSV, as well as a reduction of 67% at 3 months, and 56.8% at 6 months, in hospitalizations linked to RSV.

These two strategies are alternatives and parents will have to make a choice, as informed as possible, between the two.

The benefits of maternal vaccination

• No injection for the newborn;
• Protection from birth against RSV;
• Possible increased resistance to certain mutations of the virus.

The disadvantages of maternal vaccination

• Effectiveness is reduced if too few antibodies are made by the mother and/or transmitted to the newborn;
• The effectiveness of the vaccine gradually declines and only lasts until the baby is 6 months old;
• An increase in premature births has been demonstrated with a maternal vaccine other than Abrysvo, which is therefore subject to increased monitoring. It is also for this possible risk that vaccination is only considered in the 8th month of pregnancy (between the 32nd and 36th weeks of amenorrhea).

What are the advantages of Beyfortus?

• Effectiveness confirmed in real life since September 2023;
• Effectiveness and safety for premature newborns;
• Can be administered until the baby is 2 years old.

What are the disadvantages of Beyfortus?

• Need to perform an injection on the infant, as soon as possible;
• Risk of emergence of viral mutations likely to ultimately reduce the sensitivity of RSV to Beyfortus, justifying the interest in having a vaccine alternative.

In three specific situations, the Beyfortus monoclonal antibody should be preferred:

• when vaccination is unlikely to be effective (premature newborns, interval of less than 14 days between vaccination and birth);
• in the case of a new pregnancy in a previously vaccinated mother, due to lack of available data on the safety and effectiveness of an additional dose of vaccine;
• when the mother is immunocompromised (in the absence of data on the effectiveness and immunogenicity of the vaccine in this population).

Given the seasonal nature of RSV, the HAS recommends holding the vaccination campaign for mothers and the immunization of newborns at the same time, from September to January.

The vaccine can be administered at the same time as the flu vaccine but with an interval of two weeks before vaccination against diphtheria-tetanus-pertussis (dTca). Each year in France, nearly 30% of infants under the age of two suffer from bronchiolitis, caused in nearly three quarters of cases by RSV.

With Destination Health.

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