Vaccination for influenza in children this winter

The Health Protection Surveillance Centre has published an update on influenza vaccination for children in Ireland during the 2020/2021 influenza season

In the latest edition of its monthly publication Epi-Insight, the Health Protection Surveillance Centre (HPSC) has published an update on the 2020/2021 influenza season and influenza vaccination for children in Ireland.

The 2020/2021 influenza season presents a significant challenge to the delivery of healthcare services in the context of Covid-19, points out the HPSC. Every autumn and winter 200-to-500 people die in Ireland as a result of influenza (110 died in the 2019/20 season) and thousands of people need hospital admission, placing a considerable burden on the healthcare system.

For individuals, dual infection with influenza and Covid-19 is likely to lead to worse outcomes, particularly for those at-risk such as older people and those with underlying medical conditions.

To prevent cases of influenza in children and reduce the spread of influenza to others, the HSE’s National Immunisation Advisory Committee (NIAC) has now recommended influenza vaccine for all children in Ireland (aged two-to-17 years inclusive).

For the 2020/21 flu season, following recommendations from NIAC, the Department of Health is extending the influenza vaccination programme providing funding to the HSE to offer:

• Administration of Quadrivalent Live Attenuated Influenza (LAIV) vaccine free to all children aged two-to-12 years inclusive (to be administered intra-nasally).
• Administration of Quadrivalent Inactivated Influenza vaccine (QIV) free to all in at-risk groups, regardless of medical card or GP visit card status. This includes all those aged 65 years and over, pregnant women, children aged six-to-23 months and those aged 13-to-64 with long-term medical conditions, healthcare workers and carers.
• The aim of the extension of the influenza programme to
• children aged two-12 years is to reduce:
• morbidity and mortality from influenza in children;
• transmission of influenza to the elderly and persons in risk groups;
• influenza cases and influenza-related hospitalisations;
• transmission of influenza to healthcare workers in families with children;
• absenteeism of children from school and their parents from work.

Influenza in children

Children are among the most susceptible to influenza infection, notes the HPSC. It is estimated that 20-30 per cent of children develop influenza during each flu season compared to five to 10 per cent of adults. Children, because they have limited pre-existing immunity, are primary vectors of influenza transmission in the community and shed the virus at higher viral titres. Children transmit the flu virus for a longer period than adults. Children can transmit the influenza virus for 10 or more days, compared to six days in adults, therefore increasing spread of the disease.

Up to 10 per cent of children under 15 years attend their GP with influenza in an average flu season. Flu is an important cause of pneumonia, bronchitis, otitis media, croup and bronchiolitis in children. Incidence rates of influenza are highest in the younger age groups leading to high rates of excess outpatient visits, hospital admissions and antibiotic prescriptions.
In Ireland during the 2018/2019 flu season, 1,245 children were hospitalised with influenza. Children aged under five years had the second highest hospitalisation rates for influenza after those aged 65 years and older.

Between the 2009/10 and 2018/19 flu seasons, more than 4,750 children aged 0-14 in Ireland have required hospitalisation as a result of influenza, including 183 requiring critical care and sadly 41 children have died.

LAIV in children

Nine European countries, the US, Canada and Australia already recommend influenza vaccine for children. The UK gives LAIV to children. Finland, US and Canada give LAIV or QIV to children.

Quadrivalent LAIV vaccine is egg-based and contains four vaccine virus strains as recommended by the World Health Organisation (WHO) for the Northern Hemisphere 2020/2021 influenza season.

In some studies, LAIV has been shown to be more effective in children compared with inactivated influenza vaccines. In addition, LAIV may offer some protection against strains not contained in the vaccine, as well as virus strains that have undergone antigenic drift. A recent meta-analysis of LAIV suggested an efficacy against confirmed disease of 83 per cent.
The UK pilot primary school programme introducing LAIV was evaluated in 2014/2015 and showed:

• 94 per cent reduction in primary school-age children GP influenza-like consultations;
• 74 per cent reduction in primary school-age emergency department attendances with respiratory complaints;
• 93 per cent reduction in primary school-age confirmed influenza hospitalisations;
• 59 per cent reduction in adults GP influenza-like
• illness consultations.

Education

The HSE National Immunisation Office (NIO) has developed an e-learning module for vaccinators ‘Live Attenuated Influenza Vaccine’ which is available at www.hseland.ie. The NIO has also produced information materials on LAIV for parents and healthcare workers, which will be distributed to GPs and pharmacists. These materials will also be available online from the NIO website www.immunisation.ie and www.hse.ie/flu.

Reference: Tom Barrett, Chantal Migone, Lucy Jessop. National Immunisation Office. The 2020/2021 influenza season and influenza vaccination for children. Epi-Insight, Vol 21, Issue 4, September 2020.