High-valency pneumococcal vaccines reduce serotype-specific invasive pneumococcal disease
The introduction of high-valency pneumococcal conjugate vaccines (10- and 13-valent vaccines [PCV10 and PCV13, respectively]) reduced the incidence of invasive pneumococcal disease caused by the vaccine serotypes in young children in SpIDnet* countries, according to an observational study. However, there was an increase in pneumococcal disease caused by non-PCV13 serotypes.
“Compared with the period when the heptavalent vaccine was used, the incidence of invasive pneumococcal disease caused by all serotypes declined in the 4 years after introduction of PCV10 and PCV13,” said the researchers.
Researchers collected data on invasive pneumococcal disease incidence pre- and postintroduction of PCV10 and PCV13 in children aged <5 years from seven SpIDnet countries (Czech Republic, France, Ireland, Norway, Spain, Sweden, and UK). [Lancet Respir Med 2017;doi:10.1016/S2213-2600(17)30110-8]
There was a 47 percent overall decrease in invasive pneumococcal disease due to any serotype 4 years after the introduction of PCV10 and PCV13 (pooled incidence rate ratio [IRR], 0.53) compared with during the era of the heptavalent vaccine (PCV7).
Incidence of invasive pneumococcal disease caused by PCV7 serotypes which declined after the introduction of PCV7 further declined upon introduction of PCV10 and PCV13 (median incidence 16.5 [pre-PCV7], 3.6 [after PCV7], and 0.5 per 100,000 population [after PCV10 and PCV13; IRR, 0.16]).
Invasive disease due to serotypes 1, 5, and 7F (additional serotypes in PCV10), and 3, 6A, and 19A (additional serotypes in PCV13) also reduced following the introduction of PCV10 and PCV13 (IRR, 0.17 and 0.41, respectively, 4 years after the introduction of PCV10 and PCV13).
Median incidence of invasive pneumococcal disease caused by serotypes 1, 5, and 7F increased after the introduction of PCV7 (from 1.2 pre-PCV7 to 3.4 post-PCV7 per 100,000 population) and reduced following the introduction of PCV10 and PCV13 (2.1 per 100,000 population). Similar changes in incidence were noted for serotypes 3, 6A, and 19A (2.6 [before PCV7], 3.4 [after PCV7], and 2.4 per 100,000 population [after PCV10 and PCV13]).
In contrast, the incidence of invasive pneumococcal disease caused by non-PCV13 serotypes increased from 1.8 (before PCV7) to 3.5 (after PCV7) to 6.5 (after PCV10 and PCV13) per 100,000 population (IRR, 1.62, 4 years after PCV10 and PCV13). According to the researchers, this increase hints at serotype replacement.
The researchers acknowledged several limitations including heterogeneity of disease incidence between study sites and a lack of year 4 data in certain sites. Change in antimicrobial use and increased awareness on pneumococcal disease among healthcare professionals may also have impacted the findings.
“[However], our findings represent added value over those from studies done in single countries, which usually include low numbers of cases,” they said, and recommended increased surveillance to determine the effects of the high-valency vaccines not just in children, but also in adults and the elderly.