Pertussis vaccine switch for UK pregnant women due to polio antibody impact in children

10th July 2024

The UK is switching to a different pertussis vaccine for pregnant women following advice from the Joint Committee on Vaccination and Immunisation.

The maternal pertussis vaccination programme will move to using a vaccine that does not contain polio from July, following studies that showed this component of the vaccine had a small impact on children’s antibodies later on.

Studies reviewed by the committee at the end of 2022 showed a lower response to polio vaccination at 13 months, as well as before and after the preschool booster, in children whose mothers had been vaccinated with DtaP-IPV (diphtheria, tetanus, pertussis and polio) during pregnancy.

Analysis showed antibody levels to polio type 2 were most affected by the maternal vaccination.

The committee noted that despite the difference, all antibody responses were still above the protective threshold and were boosted by the pre-school jab.

To address the ‘potential immunity gap’ caused by the ‘blunting effect’ of the polio in the maternal vaccine, the committee said it would prefer the use of a non-polio vaccine if one could be obtained at a cost-effective price.

The priority should be to ensure that the maternal vaccine programme remains in place because it continues ‘to save lives’, the committee agreed at the time.

Updating the pertussis vaccination programme advice, UK Health Security Agency (UKHSA) officials said they had now secured a supply of Tdap (brand name Adacel) – a vaccine that contains low-dose tetanus, diphtheria and acellular pertussis – to use instead.

Any remaining stocks of the low-dose dTaP/IPV vaccine (brand name Boostrix-IPV) previously supplied for this programme ‘should be used for the pre-school booster programme in primary care’, UKHSA said.

The polio-containing vaccine can be used in maternity care settings if it is the only one available until stocks are exhausted and new supplies are received, the advice stated.

It should also be offered if Tdap is not available or is clinically contraindicated to ensure pregnant women can be vaccinated.

The vaccine is already used in maternal pertussis vaccine programmes in many other European countries, as well as in the USA and Australia, with millions of doses administered worldwide, a UKHSA spokesperson said.

Concerns have been raised over falling uptake of pertussis vaccine in pregnancy after five babies died in the first three months of this year and three more the following month.

Up to April 2024 there were 4,793 laboratory confirmed cases of pertussis compared with 858 across the whole of 2023. 

In the first few years of the maternal pertussis vaccination programme, coverage was around 70%, but has fallen year on year since 2020.

In 2022/23, pertussis vaccine coverage was 60.7% and by December 2023 it had fallen to 59.5% in England with some parts of the country seeing uptake below 40%.

A version of this article was originally published by our sister publication Pulse.

Maternal vaccination effective against infant severe RSV infection

28th April 2023

Maternal vaccination with a single dose against RSV gave rise to a high efficacy against severe infection among infants.

RSV infection leads to a global high morbidity and mortality burden in children aged 0-60 months. Moreover, the greatest risk for hospitalisation occurs during the first six months of life.

In a recent study, RSV-associated acute respiratory infection, led to the hospitalisation of one in every 56 healthy term-born infants. Whether maternal vaccination can reduce such RSV-related infection in newborns and infants remains uncertain.

In the present, randomised, double-blind, phase 3 trial, pregnant women received a single dose vaccine or placebo, between weeks 24 and 36. The two primary efficacy endpoints were severe RSV-associated lower respiratory tract illness and medically attended, less severe illness. Assessment of these outcomes took place at 90 and 180 days after birth. A lower boundary of the confidence interval > 20% was the success criterion for vaccine efficacy. 

Maternal vaccination and RSV-associated infections

Overall, 7,358 women received either the vaccine (3682) or placebo. There were six cases of severe RSV in the vaccinated group and 33 in the placebo arm within 90 days of birth (vaccine efficacy = 81.8% 99.5% CI 40.6% – 96.3%). Within 180 days, the vaccine efficacy against severe infection was 69.4% (97.58% CI 44.3 – 84.1%).

In contrast, vaccine efficacy was only 57.1% (99.5% CI 14.7 – 79.8) against less severe disease and did not meet the criteria for success.

Adverse events were similar in all groups within one month after injection or within one month after birth.