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MenC transmission appears unhindered by polysaccharide A/C vaccination
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During outbreaks of serogroup C meningococcal disease at two oil refineries in Brazil in 2010, polysaccharide A/C vaccination did not appear to prevent disease carriage or halt its transmission, according to recent findings.
In Brazil, serogroup C meningococcal (MenC) disease is currently responsible for most cases of meningococcal disease, according to researchers.
In the study, researchers investigated an outbreak of MenC disease associated with the ST103 complex at an oil refinery in Sao Paulo, identified as “refinery A.” At this facility, which employed 17,590 workers, 18 cases and three deaths were reported. Six of the cases and two of the deaths occurred in refinery A employees, and 12 cases and one death affected family members of the workers. The outbreak occurred between March 29 and June 30, 2010, and health authorities were notified March 29. The meningococcal polysaccharide A/C vaccine was recommended by health officials, and vaccination began June 30, with 90.5% coverage attained within 1 week.
A second MenC outbreak was reported at a refinery employing 16,000 workers in Sao Jose dos Campos (refinery B). The first case of MenC was confirmed July 10, 2010, and the second case was reported July 18. A subsequent investigation identified 10 additional cases, all of whom were children younger than 4 years who lived in the same household as refinery B employees. Of the 12 patients, six died. In the refinery B cases, the decision was made to provide chemoprophylaxis, rather than vaccine, to all close contacts of the case-patients. The cross-sectional study compared 483 refinery A workers, who had been advised to receive vaccine, and workers from refinery B, who had not been advised to undergo vaccination.
The researchers found that the pharyngeal carriage rate of meningococci was 21.4% in the vaccinated refinery A group and 21.6% in the nonvaccinated refinery B workers. Rates of MenC carriage were also similar; 6.3% in refinery A and 4.9% in refinery B. The researchers found that a MenC strain related to the sequence type 103 complex was implicated in Brazil’s increased incidence of meningococcal disease. Additionally, a correlation was seen between low education levels and higher risk for meningococcal carriage.
“These results represent a challenge to the current policy of using the meningococcal polysaccharide A/C vaccine to control outbreaks of MenC disease, and they have key implications for future vaccination strategies,” the researchers concluded. “Our findings emphasize the need to review such policies and to consider using [meningococcal C conjugate] vaccines rather than meningococcal polysaccharide A/C vaccines to control MenC disease outbreaks.”
Disclosure: The study was funded by Sanofi Pasteur. See the study for a full list of financial disclosures.
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