Single quadrivalent flu shot may be enough in IBD patients, but questions linger

Last Updated: 2018-04-06

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - In adults with inflammatory bowel disease (IBD), a single dose of quadrivalent inactivated influenza vaccine (QIV) appears to convey adequate immunogenicity, though some immunosuppressants might lessen the effect, according to new research.

"Although patients with IBD as a whole can obtain good immunogenicity that meets the EMA (European Medicines Agency) criteria, this study has shown that it is difficult to obtain immunogenicity in patients undergoing immunosuppressive therapy, especially those receiving IFX (infliximab), even with a QIV," Dr. Shimpei Shirai of Saga University in Saga City, Japan, and co-authors write in Inflammatory Bowel Disease, online March 9.

Dr. Shirai and colleagues randomly assigned adults with Crohn's disease or ulcerative colitis to receive either a single shot of QIV or a QIV shot plus a booster shot. In the single-vaccination group, the researchers collected serum samples before vaccination, four weeks after vaccination and after the flu season. In the booster group, they collected serum samples before vaccination, four weeks after the first vaccination, four weeks after the second vaccination and after the flu season.

Over a two-month period, 83 patients received a single shot and 49 patients received two shots; the researchers followed-up all 132 patients, 53 of whom were on immunosuppressants, for about eight months.

After one inoculation, each vaccine strain demonstrated immunogenicity that satisfied the EMA criteria (a seroconversion rate of more than 40%, a mean geometric increase of more than 2.5, or seroprotection rate of more than 70% in adults aged 18 to 60 years). The booster flu shot did not provide additional response.

In patients on infliximab, the seroprotection and seroconversion rates were significantly lower in those with serum concentrations above 0.1 mcg/ml compared with IBD patients not treated with the drug (seroprotection rate H1N1: adjusted odds ratio, 0.37; H3N2: aOR, 0.22; seroconversion rate H1N1: aOR, 0.23; H3N2: aOR, 0.19).

Dr. Atilla Ertan, a professor of gastroenterology, hepatology and nutrition at the University of Texas McGovern Medical School in Houston, told Reuters Health by email, "The prevalence of IBD is on the rise, particularly among the elderly and young children. These patients with moderate to severe IBD are usually treated with immunomodulators and/or biologic agents, resulting in increased risk of infections, including bacterial pneumonia. Inactive vaccination such as pneumococcal vaccine is crucial and is a standard immunization in all these IBD patients. IBD patients during the immunosuppressive therapy will only be inoculated with inactivated vaccines."

Dr. Ertan, who was not involved in the study, said that his center has over 3,000 IBD patients who are carefully vaccinated according to available guidelines. "However," he noted, "the efficacy of immunization in patients with IBD requiring immunosuppressive therapies has been a concern, and additional studies are needed."

Dr. Ertan pointed out several limitations to this study, "including its relatively small number of patients. Another important issue is that this observation lasted only one season." He recommended "long-term follow-up to assess whether the lower seroprotection rates in IBD patients truly lead to higher rates of influenza infection."

"Although patients with IBD as a whole can obtain very good immunogenicity with influenza vaccine in the first season, it is difficult to assess its long-term outcome," he noted.

Dr. Megumi Hara, the corresponding author, did not respond to requests for comment.

SOURCE: https://bit.ly/2DYTykK

Inflamm Bowel Dis 2018.