Safety profile of meningococcal A conjugate vaccine
GACVS received updated data on vaccine safety from campaigns to introduce MenAfriVac meningococcal A conjugate vaccine in the 3 countries (Burkina Faso, Mali and Niger) where the vaccine was introduced during December 2010. Previously, data presented from 7 phase I and phase II clinical trials at 5 sites (the Gambia, Ghana, India, Mali and Senegal), and from the pilot introduction of the vaccine in September 2010, had not indicated any cause for concern about the safety of this lyophilized vaccine. The pilot phase was followed by introduction of the vaccine into all 62 districts in Burkina Faso, 20 districts in Mali and 11 districts in Niger, covering a total population of almost 18 million: 10.7 million in Burkina Faso, 4.5 million in Mali and 2.7 million in Niger. Following a recommendation made by GACVS prior to the December 2010 rounds, an active surveillance component has been included in 1 district in Burkina Faso in addition to the enhanced passive surveillance system already in place.
Passive surveillance revealed a total of 1807 AEFIs, including 44 serious events, reported from 18.4 million people vaccinated in the 3 countries during introduction. This corresponds to a reporting rate of 9.8 AEFIs per 100 000 people vaccinated. Fever (39.2%) and local reactions (28.4%) were most commonly reported. Based on a review by national expert committees in each country, only 3/44 serious AEFIs were classified as possibly or probably related to vaccination (1 case each of acute exanthematous pustulosis, bronchospasm, and vomiting). In addition, during the pilot phase another 4 serious events were classified as possibly or probably related to vaccination (bronchospasm, meningitis-like syndrome, vomiting, and urticaria). Active surveillance for 12 pre-identified syndromes was conducted for 52 days (10 days during the vaccination campaign and 42 days after) in 16 health-care facilities in which approximately 100 000 people had been vaccinated. A total of 71 episodes of these syndromes were investigated, of which the most common were convulsion (32 cases), urticaria (18) and bronchospasm (14). The national expert committee of Burkina Faso classified these cases as coincidental. For the 3 most frequent syndromes, the distribution of the intervals between vaccination and the occurrence of symptoms did not reveal any temporal clustering.
A total of 2022 pregnant women vaccinated in Burkina Faso and Mali are also being followed to collect data on AEFIs and pregnancy outcomes.
GACVS concluded that the data from surveillance during the introduction of MenAfriVac do not indicate any reasons for concern about the vaccine’s safety. However, reports of bronchospasm and urticaria may suggest hypersensitivity reactions to vaccination, and the committee recommended that a more in-depth review of these cases be made to rule out anaphylaxis.
GACVS recognized that it would not be practical to conduct widespread active surveillance but highlighted the need for AEFI surveillance to continue as the vaccine becomes more widely available, so that additional information about its safety profile can be obtained.