There is evidence of waning immunity in individuals vaccinated against meningitis C as part of the UK infant immunisation schedule. The intention of this study is to contact participants of a previous NVEC (National Vaccine Evalutaion Consortium) clinical trial (a PreSchool Men C trial, in which participants were randomised to receive Meningitec, Menjugate or Neisvac-C). They will be invited to enrol and will be randomised to receive one of two quadrivalent meningococcal ACWY vaccines, to look at the boosting effect they may confer.

Between 550 and 650 subjects enrolled in a previous Meningococcal C vaccine study will be invited to join this new study looking at the boosting effects of two quadrivalent meningococcal ACWY vaccines. If they choose to participate, they will be randomised to receive one of the ACWY vaccines. Within each vaccine group, there will be further division into short (6 months) or longer (9 months) follow-up.

Each participant will be given one dose of an allocated vaccine. Blood samples will be taken three times from each participant - the first sample will be pre-vaccination; the second sample will be taken one month after vaccination; and the third and final sample at either six or nine months after vaccination (depending on the group they are randomised to).

Inclusion Criteria:

• Previously enrolled on the Preschool Men C study conducted by NVEC in 1999/2000
• Participant's parent or legally authorized representative is willing and able to give written informed consent for participation after the nature of the study has been explained.
• No contraindications to vaccination as specified in the "Green Book"- Immunisation against Infectious Disease, HMSO.
• Participant who gives assent for participation in the study.
• Vaccinated with Meningitec (MCC CRM) or Menjugate (MCC CRM) or NeisVac-C (MCC TT) between 3.5-6 years of age.
• Known to be free of medical problems as determined by a medical history and clinical assessment.
• Parent or legally authorised representative is willing to allow his or her child's GP to be notified of participation in the study and contacted if required for confirmation of vaccination history.

Exclusion Criteria:

• History of invasive meningococcal disease.
• Have a history of household contact or intimate exposure to an individual with culture proven Neisseria meningitis disease in the previous 60 days.
• Any vaccination against MenC disease since MCC vaccine given between 3.5 to 6 years.
• Participant is pregnant.
• Confirmed or suspected immunosuppressive or immunodeficient conditions, including human immunodeficiency virus (HIV) infection.
• Major congenital defects or serious chronic disease including progressive neurological disease or seizure disorder.
• Have a known bleeding diathesis, or any condition that may be associated with a prolonged bleeding time.
• Have a history of severe allergic reactions after previous vaccinations such as anaphylactic shock, asthma, urticaria, or other allergic reaction or hypersensitivity to any vaccine component.
• Have received another investigational agent within 90 days or before completion of the safety follow-up period in another study, whichever is longer, prior to enrollment and unwilling to refuse participation in another investigational trial through the end of the study.
• In the event that administration of another licensed vaccine is needed during the study, this vaccine should not be administered within 30 days of any study injection according to investigator's judgment (exception: licensed flu-vaccine should not be administered within 14 days of study vaccines).
• Have received any blood or blood products within the past 12 weeks.
• Have any other significant disease or disorder which, in the opinion of the investigator, may either put the participant at risk because of participation in the study, or may influence the result of the study, or the participant's ability to participate in the study.

Temporary Exclusion Criteria

• Receipt of systemic antibiotics (either oral or parenteral) will delay enrolment until at least 7 days after cessation of antibiotics.