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17-01-2012 | General practice | Article

Two-dose vaccine for meningitis B developed


Free abstract

MedWire News: Researchers have developed a vaccine against group B meningococcal disease that provides highly effective protection after two doses.

Of the six major serogroups of meningococcal disease, effective vaccines have been developed against groups A, C, W-135, and Y, but creating a serogroup B vaccine has proved difficult due to its unusual immunogenic properties.

Miguel O'Ryan (University of Chile, Santiago) and colleagues used a whole genome-sequencing strategy to create a four component vaccine targeting different parts of the bacterium known as 4CMenB.

Writing in The Lancet, O'Ryan and team describe the results of a study carried out to test the best dosing strategy for the vaccine in 1631 Chilean adolescents between the age of 11 and 17 years (mean age 13.8 years).

The participants received placebo (n=128), one dose of the vaccine (n=375), two doses 1 month apart (n=375), two doses 2 months apart (n=380), or three doses 1 month apart (n=373).

The researchers tested the degree of immunogenicity achieved following vaccination by assessing the degree of bactericidal activity in human complement (hSBA) against three reference strains.

O'Ryan and colleagues found that 99-100% of adolescents who received two or three doses of 4CMenB achieved hSBA titers of 4 or more against the test strains of group B meningococcal bacteria, compared with 92-97% and 29-50% of those who received one dose and placebo, respectively.

When the participants were retested 6 months after their initial vaccination, 91-100% of those who had two or three doses of the vaccine retained an hSBA titer of 4 or more compared with only 73-76% of those who had one dose.

A total of 456 participants had an additional dose of 4CMenB at 6 months and were followed up 1 month later. Seroresponse rates of 99-100% were achieved for all strains after a second or third dose at 6 months, notes the team.

No serious vaccine-related adverse events were reported by the researchers. Local and systemic reactions were reported more commonly after injection with the vaccine than with placebo, but they were generally mild and transient with the most common of each being injection site pain (86%) and malaise (51%), respectively.

"Further study is needed to provide information about the immunogenicity and tolerability of 4CMenB in various age groups, including infants, who bear the largest disease burden worldwide," write the authors.

They add: "The extent of this protection against meningococcus B variants circulating worldwide will be determined by national surveys."

By Helen Albert

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