Pregnant Women with RA Have Similar Incidence of Influenza-Like Illness to Those without Autoimmune Disease

SAN DIEGO, CA—Pregnant women with rheumatoid arthritis (RA) who received an influenza vaccination had a similar incidence of influenza-like illness compared with women without autoimmune disease, a study presented at the 2013 ACR/ARHP Annual Meeting has found.

Noting that risk of infection with influenza poses a significant risk to pregnant women—with the recommendation that all pregnant women be vaccinated—what is unknown is “whether the protective effect of influenza vaccine is the same for pregnant women with RA as it is for pregnant women without autoimmune disease,” noted Yunjun Luo, MS, of the Department of Pediatrics, UC San Diego and Rady Children’s Hospital, San Diego, in explaining the rationale for the study.

Luo and colleagues obtained data from an ongoing prospective cohort study of pregnancy outcomes among American and Canadian women enrolled between 2009 and 2012. Included were those with a current diagnosis of RA.

“All women had completed multiple standard maternal telephone interviews during pregnancy that contained structured questions on the receipt of influenza vaccination and the occurrence of a diagnosis of influenza-like illness during pregnancy,” Luo reported. They compared women who reported receipt of an influenza vaccine at some point in pregnancy to women without vaccine during pregnancy.

Of the 1233 pregnant women, 825 had received influenza vaccine. Among the 245 pregnant women with RA, 144 (58.8%) were vaccinated. The majority of the 988 women without autoimmune disease were vaccinated, 681 (68.9%).

Nine (3.7%) of the women with RA and 55 (5.6%) of the women without autoimmune disease reported a diagnosis of influenza-like illness at some point in their pregnancies. Of those vaccinated, 6 (4.2%) with RA and 28 (4.1%) without autoimmune disease reported influenza-like illness at some point in their pregnancies.

The adjusted hazard ratio for influenza-like illness in women vaccinated vs. women not vaccinated was 1.19 (95% CI 0.64–2.24). The interaction term for vaccine exposure and autoimmune disease was not statistically significant (P=0.16).

“We found no evidence that the effect of influenza vaccine to pregnant women with RA was different to the effect of influenza vaccine to pregnant women without autoimmune disease,” the researchers concluded.