UK study: 13-strain pneumococcal vaccine (PCV13) 75% effective
The 13-valent pneumococcal conjugate vaccine (PCV13) was 75% effective in preschoolers but 90% effective against the strains covered in the seven-valent vaccine (PCV7), according to a British study in Lancet Infectious Diseases.
The UK researchers who conducted the study also found that correlates of vaccine protection varied widely by Pneumococcus strain, or serotype. They analyzed data from 706 cases of invasive pneumococcal disease (IPD) in children 2.5 to 56 months old.
They found PCV13 effectiveness after two doses before age 1 year or one dose in older kids to be 75% (95% confidence interval [CI], 58%-84%). Vaccine effectiveness (VE) was 90% (95% CI, 34%-98%) for the PCV7 serotypes and 73% (95% CI, 55%-84%) for the six additional serotypes included in PCV13.
In addition, the team found that VE for PCV13 and PCV7 was lower than predicted by the aggregate correlate of protection of 0.35 microgram per milliliter (mcg/mL) used during licensing. But correlates of protection were higher than 0.35 mcg/mL for serotypes 1, 3, 7F, 19A, 19F, and lower than that mark for serotypes 6A, 6B, 18C, and 23F.
A related commentary in the same issue said that, to maximize protection, the correlate of protection cutoff would need to be increased for some serotypes and relaxed for others in future vaccines. "However, more data is still needed before changes in correlate of protection criteria for licensing new PCVs can be consistently made."
The commentators added, "Of note, almost 60% of invasive pneumococcal disease cases that occurred in the study setting (414 of 706) were caused by serotypes not covered by the current PCV13, suggesting that new supplemented PCVs will probably be needed in the medium term."
Jul 18 Lancet Infect Dis abstract
Jul 18 Lancet Infect Dis commentary
Danish study: PCV13 dropped pneumococcal disease 21%
A Danish study published in Clinical Infectious Diseases found that introduction of PCV13 was associated with a 21% reduction in IPD.
The investigators analyzed national data during a baseline period (2000-07), PCV7 use (2008-10), and PCV13 implementation (2011-13). Compared with PCV7 years, IPD incidence declined 21% in the whole population and 71% in children younger than 2 years in the PCV 13 years.
Compared with pre-PCV years, the general population saw a 28% reduction in IPD-related 30-day mortality during the PCV13 years, the researchers noted. The decline in death rates was seen across all age-groups.
"PCV13 has brought greater benefits than we had expected in our setting," the authors conclude.
Jul 16 Clin Infect Dis abstract
