Managing fever following infant vaccination

Introduction

Australia is fortunate to have a comprehensive, safe, free and readily accessible immunisation program that reduces occurrence of, and harm from, vaccine-preventable diseases.

Australia’s National Immunisation Program is available for babies, young children, teenagers and older Australians, as well as people of all ages who are at greater risk of serious harm from certain diseases.¹

Vaccines administered in Australia are effective and safe.

The majority of adverse reactions that follow vaccinations are minor and short-lived, and serious reactions are rare.

These assurances of vaccination safety encourage nationwide uptake of vaccination programs.^1-3

Nevertheless, the responsibility of managing immediate and post-vaccination adverse reactions following vaccinations is largely borne by concerned parents who regularly turn to health professionals, including pharmacists, for advice.

No parent wishes to see their child in discomfort — even for a worthwhile intervention such as immunisation.

Parental concerns can include management of distress and pain at time of vaccination, sleep disturbances, injection site reactions, and post vaccination discomfort and fever.

This article considers the routine administration of common non-prescription medicines to pre-emptively manage fever following infant vaccination.

Incidence of fever as an adverse effect

Adverse effects following vaccination may be immediate (e.g. anaphylaxis or fainting) or delayed (e.g. fever, tiredness or inflammation at the site of injection).

The incidence of fever as an adverse event following vaccination varies from 1% to 10% for many vaccinations but may be as frequent as 30% to 70% when multiple vaccines or multiple-component vaccines are administered.

The temperature of patients affected by fever following vaccination seldom exceeds 39 °C and is typically self-limiting.⁴

However, the need to manage fever and discomfort following vaccination, particularly among children, can result in additional presentations for medical advice and the use of parental leave by one or both parents.

This has an individual and societal economic impact and contributes to parents using antipyretic medicines prophylactically to avoid fever following vaccination.⁴

Both paracetamol and ibuprofen are effective medicines for reducing fever and pain following vaccination.

Ibuprofen is indicated for infants and children aged over three months, paracetamol is indicated from one month of age.⁵

Pre-emptive administration of antipyretics can reduce the immune response from vaccination

In 2009 a study observed that prophylactic administration of paracetamol in infants aged 9–16 weeks reduced the immune response and seroconversion rates following vaccination.^6,7

This was an observation which had previously not been observed and led to considerable subsequent research of this effect.

Studies have confirmed the association between administration of antipyretic medicines prior to vaccination and the subsequent response to vaccination.

The observed effects vary by vaccine, antipyretic agent and timing of administration.

The clinical significance of these findings is unclear as the immune responses elicited are likely to be sufficient to prevent disease in populations with high immunisation rates.^7-9

The current advice provided by a range of highly regarded references is that antipyretic medicines should not generally be administered for routine prophylaxis against fever prior to, or at the time of, infant vaccination.^3,10,11

Fever associated with Meningococcal B vaccination (Bexsero^®)

A notable exception to the advice on pre-emptive administration of antipyretic medicines is the early childhood meningococcal B vaccine (Bexsero^®).

While fever is a common reaction following any vaccine, it is more common with Bexsero^® and occurs more frequently when Bexsero^® is co-administered with other vaccines.^12,13

Around 50–60% of infants will develop fever ≥ 38.5 °C when Bexsero is given with other routine immunisations. The fever usually peaks after six hours and subsides within 24–48 hours.¹⁴

Prophylactic use of paracetamol reduces the incidence and severity of fever without affecting the immunogenicity of either Bexsero^® or other routine vaccines given at the same visit.

The effect of antipyretics other than paracetamol on the immune response has not been studied.^13,15

Current recommendations

Routine pre-emptive use of paracetamol to prevent fever at the time of vaccination is no longer recommended, except for children who have a history of seizures.

If a child has a temperature higher than 38.5 °C after a vaccination and this is making them uncomfortable, paracetamol or ibuprofen can be given to help ease any discomfort.^10,16

An exception to this advice is the specific recommendation to give pre-emptive paracetamol when administering the early childhood Meningococcal B (Bexsero^®) vaccine.

The prophylactic use of paracetamol is recommended with every dose of Bexsero^® administered to children <2 years of age to reduce the probability and severity of fever that may develop.

The first dose of paracetamol (15 mg/kg per dose) is recommended within the 30-minute period prior to vaccination, or as soon as practicable afterwards, regardless of the presence or previous development of fever.

This can be followed by two further doses of paracetamol given six hours apart.

Conclusion

Pharmacists can maximise patient comfort, reinforce confidence in Australia’s immunisation system, increase seroconversion rates following vaccination, and encourage compliance with the National Immunisation Program Schedule by providing accurate and appropriate advice to parents and carers.

In general, infants and children should not receive prophylactic doses of antipyretic medicines prior to, or at the time of, vaccination.

The exception to this advice is when Bexsero^® is administered to young children, at which time paracetamol should be administered pre-emptively and for two additional doses six hours apart.

Kevin de Vries, Resource Development Pharmacist, The Pharmacy Guild of Australia

References available on request.