4CMenB demonstrates effectiveness, does not induce herd protection
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In separate studies, the capsular group B meningococcal vaccine, or 4CMenB, demonstrated close to 60% effectiveness against meningococcal group B disease in a vaccination program for infants in England, but did not provide herd protection among adolescents during a trial in Australia, researchers reported in The New England Journal of Medicine.
The results are “good news and bad news” for 4CMenB, according to an accompanying editorial written by Lee H. Harrison, MD, head of the infectious diseases epidemiology research unit at the University of Pittsburgh School of Medicine, and David S. Stephens, MD, chair of the department of medicine at Emory University School of Medicine.
Harrison and Stephens noted that the CDC’s Advisory Committee on Immunization Practices recommends routine MenB vaccines for high-risk patients in the United States, and shared clinical decision making in patients aged 16 to 23 years who are not at an increased risk.
“The vaccines are not recommended routinely in persons in this age group because of the current historically low meningococcal disease burden in the United States and unanswered questions about the vaccines,” they wrote. “For example, what is the vaccine effectiveness against invasive meningococcal capsular group B disease? Do the vaccines reduce the prevalence of pharyngeal carriage and therefore confer herd protection?”
‘Real-world’ evidence
The English study “is the first real-world study to show that the vaccine protects against invasive MenB disease in infants and young children,” said Shamez N. Ladhani, MRCPCH, PhD, a clinical epidemiologist at Public Health England and part of the Pediatric Infectious Diseases Research Group at St George’s, University of London.
“This study was largely possible because of consistently high MenB vaccine uptake and the near real-time monitoring of all cases of meningococcal disease across England,” Ladhani told Healio.
Ladhani and colleagues examined the effectiveness of the United Kingdom’s 2015 MenB vaccine program during its first 3 years of implementation. To do this, they compared observed disease incidence with expected incidence during the 4-year pre-vaccination period and with the use of disease trends in in children aged younger than 5 years who were ineligible to receive the vaccine.
During the first 3 months of 2018, 92.5% of children had completed primary immunizations by their first birthday and 87.9% had received all three doses by 2 years of age. From September 2015 to August 2018, MenB disease incidence in England was significantly lower in vaccine-eligible cohorts than the expected incidence (63 vs. 253 cases; incidence rate ratio = 0.25; 95% CI, 0.19-0.36), and a 75% reduction was observed in age groups who were fully eligible for vaccination.
They calculated the adjusted vaccine effectiveness against MenB as 52.7% (95% CI, –33.5 to 83.2) with a two-dose priming schedule in infants and 59.1% (95% CI, –31.1 to 82.2) with a two-dose priming schedule and booster at 1 year. An estimated 277 (95% CI, 236-323) MenB cases were prevented over the 3-year period, with 169 total cases of MenB identified in the vaccine-eligible cohorts.
No herd immunity
A second study performed by Helen S. Marshall, MD, of the Women and Children's Health Network’s vaccinology and immunology research trials unit, and colleagues examined the 4CMenB vaccine’s effectiveness in preventing MenB transmission and inducing herd immunity among Australian adolescents.
They included 24,269 students aged 15 to 18 years in South Australia, randomly selecting students to receive the vaccine at baseline or 12 months. The primary outcome was oropharyngeal carriage of disease-causing Neisseria meningitidis, with carriage prevalence and acquisition of all N. meningitidis as secondary outcomes.
At 12 months, the researchers found no difference in the prevalence of carriage of disease-causing N. meningitidis between the vaccination group (2.55%) or the 12-month control group (2.52%). Additionally, no significant differences in secondary carriage outcomes were detected.
“It has taken decades of research and development to finally have licensed meningococcal group B vaccines,” Harrison and Stephens wrote. “The studies in this issue underscore the major progress that has been made. However, they also highlight the need for improved meningococcal group B vaccines.”
Ladhani also noted the U.K. 4CMenB vaccine program’s potential to be implemented in countries with particularly high instances of MenB.
“Each country must make its own decision on whether to implement the vaccine into their national immunization program,” Ladhani said. “The growing international evidence for the vaccine's effectiveness and safety during the 5 years since the vaccine was licensed should help support the implementation of the vaccine in countries with a significant burden of MenB disease.” – by Eamon Dreisbach
References:
Ladhani SN, et al. N Engl J Med. 2020;doi: 10.1056/NEJMoa1901229.
Harrison LH, et al. N Engl J Med. 2020;doi: 10.1056/NEJMe1916440.
Marshall HS, et al. N Engl J Med. 2020;doi:10.1056/NEJMoa1900236.
Disclosures: Ladhani reports contract work for GSK, Pfizer, MSD and Sanofi Pasteur unrelated to the study. Please see the full studies for the additional authors’ relevant financial disclosures.
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