Infants and toddlers have higher rates of hospitalization due to influenza than older children and young adults, and a new groundbreaking study led by the BC Centre for Disease Control (BCCDC) suggests a simple way to improve their vaccine protection.
This study, called TITRE or TIV (Trivalent Influenza Vaccine) Infant-Toddler Response Evaluation, was published this week in PEDIATRICS, an official peer-reviewed journal of the American Academy of Pediatrics.
The study enrolled more than 250 infants and toddlers six to 23 months of age across Canada. The children had never before received influenza vaccine and were randomly assigned to receive either two full (0.5mL) doses or the current standard of two half (0.25 mL) doses of vaccine to protect against seasonal influenza viruses. Researchers wanted to see if the full dose vaccine could improve antibody response in these children without increasing side effects, notably fever.
"This study contributes valuable knowledge about the best way to protect very young children from influenza," said lead investigator Dr. Danuta Skowronski of BCCDC, an agency of the Provincial Health Services Authority. "Compared to half-dosing, the increase in antibody protection with the full dose in infants was almost 30 per cent for two of the three viruses included in the vaccine. And importantly, rates of fever reactions were not increased."
In Canada and the United States, expert committees have long recommended that the dose of influenza vaccine given to children less than three years of age should be cut in half. This half-dosing recommendation was made because of concerns raised decades ago about increased fever in young children given a full dose of a now obsolete whole virus vaccine.
With the switch to safer split virus vaccines in the 1980s, the best dose for young children was not re-assessed. Currently, some countries in Europe permit full doses to be given to young children, while in North America and Australia, the dose is routinely cut in half.
"This is the first publication to directly assess this issue, and it will help to clear up different recommendations and to make immunization policies more consistent, clear, and evidence-based," added Dr. Robert Brunham, provincial executive director of BCCDC. "If adopted in B.C. or throughout Canada, it would also mean that everyone gets the same dose of vaccine, simplifying the immunization process for doctors and nurses."
This study was led by BCCDC and was a collaboration between centres across Canada including BCCDC, the Vaccine Evaluation Centre at the Child & Family Research Institute in British Columbia, the Institut national de santé publique du Québec (INSPQ), the McGill University Health Centre (MUHC) Vaccine Research Unit in Quebec, and the Canadian Centre for Vaccinology in Nova Scotia.