• Open Access

Influenza H1N1 (swine flu) vaccination: a safety surveillance feasibility study using self-reporting of serious adverse events and pregnancy outcomes


Dr Isla S Mackenzie, Medicines Monitoring Unit (MEMO), Level 7, Ninewells Hospital, University of Dundee, Dundee DD1 9SY, UK. Tel.: +44 13 8263 2575. Fax: +44 13 8274 0209. E-mail: i.s.mackenzie@dundee.ac.uk



• While the new H1N1 vaccines underwent the usual rigorous safety and efficacy testing, concerns remained that there may be unexpected side effects of the vaccines.

• The strategy for H1N1 vaccine pharmacovigilance in the UK consisted of two patient studies by the two vaccine manufacturers, 14 small scale studies supported by the National Institute of Health Research, monitoring by specialist neurologists and the MHRA.

• There were calls to investigate the feasibility of a large-scale prospective active surveillance system for ‘near real-time’ vaccine safety monitoring that would be complementary to the other aforementioned initiatives.


• This pilot study demonstrated that collecting ‘near real-time’ reporting of event data from patients who experienced side effects as well as those who reported no problems after swine flu vaccination is feasible.

• The use of information technologies improves patient involvement in research as well as dramatically limiting the cost of the study.

• The online methodology facilitates rapid surveillance in response to urgent safety issues.


During the global H1N1 influenza A (swine flu) pandemic 2009–2010, swine flu vaccines were expeditiously licensed and a mass vaccination programme for high risk groups, including pregnant women, was introduced in the UK. This pilot active safety surveillance study was performed to establish the feasibility of rapidly monitoring the new swine flu vaccines in large patient numbers receiving or offered the vaccination under normal conditions of use within a short time frame.


A cohort design with safety data capture through modern technologies was carried out in Scotland, UK during the winter swine flu vaccination programme 2009–2010 in individuals receiving or offered the swine flu vaccination. The main outcome measures were self-reported serious adverse events (SAEs) and pregnancy outcomes.


The cohort comprised 4066 people; 3754 vaccinated and 312 offered the vaccination but not vaccinated. There were 939 self-reported events (838 different events), 53 judged to fit SAE criteria by the investigators, with nine judged as possibly, probably or definitely vaccine related. None of the seven deaths (six in vaccinees) were judged as vaccine related. One hundred and twenty-eight women reported 130 pregnancies during the study with 117 pregnant at study start. There were reports of four miscarriages in three women and six possible congenital abnormalities in live births.


Overall, no significant safety issues were identified. The methodology and use of modern technologies to collect safety data from large numbers of patients was successful and could be used again in similar safety studies.