Developments in childhood vaccination

Reference: October 2024 | Issue 10 | Vol 10 | page 24

Over the past two years, the cases of young children who died from invasive Group A Streptococcus (iGAS) have starkly illustrated the potential for this disease to progress rapidly and with severe consequences.

According to the Health Protection Surveillance Centre (HPSC), last year saw cases of iGAS rise dramatically in Ireland – from 99 reported infections in 2022 to 533 in 2023. The average during the pre-pandemic years 2017-2019 was 126 cases. In 2023, there were 12 adult and eight paediatric deaths, according to the HPSC’s Report on invasive iGAS infections in Ireland, published on 23 January 2024.

Data

Data analysis by the HPSC showed evidence of circulation of particular sub-types or emm-types during the last year. Certain emm-types, such as emm1, emm3, and emm12, are known to be associated with more severe disease and worse outcomes.

In recent years, cases associated with the emm1 subtype have been rising. They increased from 14 per cent of cases in 2019 to 41 per cent in 2022. The rise continued in 2023, when they accounted for over half (55 per cent) of cases, according to the HPSC’s January 2024 report. The document states emm12 accounted for 22 per cent of cases.

Varicella

In the report, the HPSC also noted there was an increase in hospitalised varicella (chickenpox) especially among children (0-17 years). This increase in varicella drove, in part, the iGAS surge in 2023. A well-established link exists between varicella infection and the later development of iGAS in children. Numerous studies indicate that approximately 20 per cent of iGAS cases are preceded by a varicella infection.

In the recent upsurge, almost a fifth (17 per cent) of children were co-infected with varicella and iGAS, while varicella was reported “as a risk factor” in almost a quarter of children (23 per cent) with iGAS. Another HPSC report, Infectious Disease Notifications in Ireland 2019-2023, shows how varicella cases requiring hospitalisation rose from 75 in 2022 to 170 last year. Immunocompromised children are especially vulnerable to varicella and its complications, such as meningitis, stroke, encephalitis, and iGAS.

Vaccine

The link between varicella and iGAS in children is one of the reasons why the recent approval of the varicella vaccine for inclusion in our immunisation programme is very welcome. The vaccine, which has been available since the 1970s, is included in a number of national childhood vaccination programmes worldwide. While the vaccine was available privately in Ireland for some time, it is not included in the primary childhood immunisation programme in this country.

However, the national immunisation advisory committee (NIAC) recommended this should change.
As a result of its recommendation, the Department of Health asked HIQA to carry out a health technology assessment (HTA) on the subject. In July 2023, after conducting the HTA, HIQA found that there was “clear and consistent evidence” that the vaccine is both safe and effective in preventing varicella and its complications. Adding the vaccine to the childhood immunisation programme is likely to be cost-effective, according to the Authority.

Minister for Health Stephen Donnelly recently confirmed plans for the vaccine to be introduced into the childhood vaccination programme next year. “Having considered the findings of the HTA, I have approved the introduction of the varicella vaccine into the primary childhood immunisation programme, subject to funding being made available via the 2025 Estimates process,” Minister Donnelly stated in March. He was responding to a question from Deputy Colm Burke, who has since been appointed Minister of State for Public Health, Wellbeing and the National Drugs Strategy.

Shingles

The varicella-zoster virus, which causes varicella, can reactivate later in life and cause shingles. While some people experience severe disease or continue to experience pain for months, or even years, for most people symptoms normally resolve within a month. While shingles vaccines are available in Ireland, the HSE does not currently provide free vaccination.

The incidence and severity of shingles increases with age, with most cases occurring in people over the age of 50 years. People who are immunocompromised are also at an increased risk of shingles. HIQA recently assessed shingles vaccination for adults aged 50 years and older and for those aged 18 years and older who are at increased risk of shingles.

Dr Conor Teljeur, HIQA’s Chief Scientist, said in March: “Our assessment found that the shingles vaccine is safe and effective, but the benefit of the vaccine decreases over time. However, at the current vaccine price, adding shingles vaccination to the routine immunisation schedule for the general population aged 50 years and older would not be a good use of HSE resources.”

HIQA has published its draft findings to give members of the public an opportunity to provide feedback on the content.

RSV

Another positive development is the new infant respiratory syncytial virus (RSV) immunisation pathfinder programme. Details of the programme were announced by the Government last month. The programme, which will run between September 2024 and February 2025, aims to ease the burden that RSV places on the healthcare service by reducing the number of illnesses and hospitalisations among young children.

It follows advice from the NIAC recommending the use of monoclonal antibody immunisation for the 2024/2025 season. The vaccine will be offered to an estimated 28,000 infants during this period. Based on evidence from a similar programme implemented in Spain, it is estimated that the infant RSV programme in Ireland will lead to the avoidance of up to 453 hospitalisations and up to 48 intensive care unit admissions.

Acting Chief Medical Officer Dr Colette Bonner said: “This pathfinder programme will help to protect young babies from the impact of RSV and safeguard health service capacity during this coming winter season. I would encourage parents of eligible infants to take the opportunity to protect their child against RSV and avail of the immunisation as it becomes available.”

Minister Donnelly said: “I’m delighted to have secured Government approval for this programme that directly and swiftly responds to this issue and will hopefully deliver an immediate impact by reducing illness and minimising the burden on our healthcare resources over the winter.”

The programme is being implemented by the HSE as a temporary measure for the 2024/2025 RSV season and may be modified following the outcome of HTAs on RSV immunisation currently being undertaken by HIQA.

Influenza

Another vaccine that should be mentioned is the influenza vaccine. Last December, it was announced that the nasal spray influenza vaccine was being made available free-of-charge to children aged two to 17. This meant that all children aged two to 17 were eligible for the influenza vaccine as part of the 2023/2024 seasonal vaccination programme

Influenza spreads easily, infecting both children and adults. Children are among those at higher risk of severe complications. Over the last decade in Ireland, thousands of children have been hospitalised due to influenza, with many requiring intensive care. Complications include pneumonia, bronchitis, and on rare occasions encephalitis.

Vaccination results in reduced risk of infection, but also reduces the risk of transmission to others including siblings, parents, and grandparents. It also reduces the need for hospitalisation and alleviates the strain on acute services during the busy winter season. The availability of these vaccines has great potential to protect children from serious illness this coming winter and take the pressure off hospital beds.