Meningitis A conjugate vaccine
The Committee was updated on vaccine safety data relating to the introduction of MenAfriVac vaccine collected in the 3 early-adopter countries (Burkina Faso, Mali and Niger) during September 2010. The data previously presented from 7 clinical trials from 5 sites (Gambia, Ghana, India, Mali and Senegal), involving 4614 participants, did not identify any unexpected safety issues with this lyophilized meningitis A conjugate vaccine.5 During the initial phase, 4 districts in the 3 countries were selected for vaccine introduction. Spontaneous AEFI reporting was stimulated during preparatory training activities and supported by national AEFI review committees in all 3 countries.
A total of 215 reports of AEFI, including 34 serious adverse events, were received after 1.04 million people were vaccinated. Based on a review by national expert committees, only 1 serious AEFI (an anaphylactic reaction) was classified as related to vaccination. So far, these data do not suggest that there should be any special concern about safety. However, GACVS had concerns about the completeness of ascertainment of AEFI. Data were collected largely through existing passive surveillance systems, and could not be compared to background rates of occurrence of the conditions of interest in the same populations.
Based on GACVS’s recommendations, the 3 countries have developed a modified postmarketing surveillance plan for the next phase of vaccine introduction in order to generate additional data on safety. The Committee recognized that it would not be practical to adopt a large-scale active surveillance approach and therefore recommended giving priority to enhancing existing surveillance systems. Active surveillance, focusing on selected syndromes of interest, will be conducted in sentinel sites that have adequate infrastructure.
The Committee also addressed precautions from the package insert recommending that the vaccine should not be administered during pregnancy unless there is definite risk of group A meningococcal disease, and lactating women should not be given the vaccine since it is not known whether it is excreted in breast milk. The Committee noted that this kind of precautionary statement has also been used for other inactivated vaccines, including other meningococcal conjugate vaccines, and is not based on any known risks to these groups. Given the clear benefits of the vaccine, the increased risk of disease in the geographical area and past experiences using similar vaccines in comparable conditions, GACVS supported WHO’s technical guidance that MenAfriVac should be offered to pregnant and lactating women residing in the meningitis belt during any stage of pregnancy or lactation. A plan should be developed to follow up vaccinated pregnant women in antenatal or obstetric clinics, and to monitor pregnancy outcomes by making appropriate comparisons with unvaccinated pregnant women.
GACVS highlighted the importance of developing a robust postmarketing surveillance plan for any new vaccine before it is introduced. Furthermore, GACVS emphasized the importance of considering whether to conduct studies in specific groups during the product development stage, especially those groups which may be at higher risk of disease from vaccination.
GACVS concluded that the data for MenAfriVac vaccine had identified no safety concerns regarding the use of this vaccine. However, GACVS emphasized the need for additional effective postmarketing surveillance to provide more complete information about the safety profile of the vaccine, including its effects in specific groups, especially pregnant women.