Using SMS technology to verify the safety of seasonal trivalent influenza vaccine for pregnant women in real time

To the Editor: Despite evidence supporting the safety and benefits of influenza vaccination during pregnancy,1,2 half of pregnant women believe the influenza vaccine to be unsafe or are uncertain about its safety in pregnancy.3 Other studies report confusion among antenatal care providers about the safety of influenza vaccination during pregnancy, and cite the need for more professional education.4

To help address these safety concerns, the Western Australian Department of Health (WA DOH) established a system to query pregnant women who have received the influenza vaccine about potential adverse events. Between 1 March and 15 May 2013, 2203 pregnant women in WA who received the 2013 influenza vaccine were reported to WA DOH. Women who gave permission to be contacted and provided a mobile telephone number (1852 women; 84%) were sent an SMS (short message service) message asking if they had experienced any reaction to the vaccine in the week after the vaccine was administered. The message requested a yes or no response. Respondents answering yes to the SMS and those who did not respond were followed up with a telephone interview.

A total of 1425 SMS responses were received (a 77% response rate); 1271 respondents (89.2%) reported no reaction in the week after being vaccinated. As shown in the Box, the most frequently reported symptom after vaccination was a local reaction at the injection site (3.6%). Other symptoms were reported infrequently (in 2% of women or fewer).

Twelve women (0.8%) reported seeking medical advice for the post-vaccination reaction they reported. Two reports classified as “other events” were considered potentially important and warranted further investigation. The first was a spontaneous abortion in which the absence of a fetal heartbeat was detected during the same appointment that the vaccine was administered. The second was an episode of self-reported decreased fetal movement; subsequent medical evaluations did not corroborate a decrease in fetal movements, and a healthy infant was delivered at term. Both of these events were considered unlikely to be caused by influenza vaccination.

Using SMS technology, WA DOH established a rapid system for monitoring influenza vaccine safety in near real-time. The rates of reactions after vaccination are consistent with those of previously published data in pregnant women5 and support the safety of the 2013 influenza vaccine for use in pregnant women.