Paracetamol: routine use may affect infant vax response
23 October 2009
Parents should be discouraged from routinely giving paracetamol following infant immunisation, in light of trial findings suggesting it may interfere with the immunogenicity (ability to produce an immune response) of several vaccines in the schedule.
Researchers have found that babies’ antibody responses are reduced with early administration of paracetamol, and it also has no effect on the occurrence of high fever (Lancet 2009; 374: 1339).
Experts from the US Centres for Disease Control and Prevention said the surprising findings presented a ‘compelling case’ against routine use of paracetamol.
Sydney paediatrician Dr Nick Wood said the findings backed current national guidelines advising against routine prophylactic (preventive) use of paracetamol, but should not deter parents from giving babies a dose if they developed a fever.
The 2 randomised studies showed antibody responses to pneumococcal, Haemophilus influenzae type b (Hib), diphtheria, tetanus and one of the whooping cough vaccines were reduced significantly when healthy 12-week old babies were given paracetamol 3 times in the 24 hours after vaccination.
The study examined fever and immune responses in 459 infants in the Czech Republic given both primary and booster doses.
The percentage of children running a temperature was significantly lower in the group getting paracetamol, but fever greater than 39.5 degrees Celsius was uncommon in both groups.
The researchers also analysed 10 previous studies involving 3700 vaccine recipients, which supported their finding that paracetamol interfered with vaccine response if administered before, rather than after, fever.
Dr Wood, clinical research fellow at the National Centre for Immunisation Research and Surveillance, said the Australian Immunisation Handbook had recommended against routine prophylactic paracetamol for at least the last 3 editions.
“I would say to parents not to worry too much if fever is around 38 degrees, but if you have to give a dose of paracetamol, give one, but don’t give several [in 24 hours],” he said.
“If I have a child with fever of 40 degrees, I think I would like to reduce their symptoms.”
While paracetamol interfered with vaccines, the infants still developed protective antibodies, he said.
The study authors concluded the clinical relevance of their immunological findings was unknown.
Last Reviewed: 23 October 2009
- 1. Prymula R, Siegrist C, Chlibek R, et al. Effect of prophylactic paracetamol administration at time of vaccination on febrile reactions and antibody responses in children: two open-label, randomized controlled trials. Lancet 2009; 374: 1339-50
