Further evidence for the effectiveness of PCV10 against Streptococcus pneumoniae serotype 19A

Emergence of serotype 19A Streptococcus pneumoniae after PCV10 associated with a ST320 in adult population, in Porto Alegre, Brazil

Use of pneumococcal conjugate vaccines has caused emergence of non-vaccine serotypes. No Brazilian data specifically about serotype 19A are available. We aimed to evaluate the frequency of occurrence, susceptibility profile and molecular epidemiology of serotype 19A before and after vaccine introduction in Brazil. Pneumococcal identification was performed by the conventional method. Strain serotype was determined by multiplex polymerase chain reaction (PCR) and/or Quellung reaction. Resistance was determined by Etest^® and PCR was performed to determine the presence of macrolide resistance genes, ermB and/or mefA. Pneumococci were typed by Multilocus Sequence Typing. Thirty-eight serotype 19A Streptococcus pneumoniae were recovered, mostly from invasive diseases. Prevalence of serotype 19A increased following vaccination (from 3.5% before vaccination to 8.1% after, p = 0.04196). Non-susceptibility increased to most antimicrobials after vaccine introduction and was associated with clonal complex (CC)320. MLST showed nine different STs, which were grouped in one main CC: CC320 (63.9%). During the post-vaccination era, the frequency of this serotype increased significantly from 1.2% in 2011 to 18.5% in 2014 (p = 0.00001), with a concomitant decrease in the genetic variability: ST320 consistently predominated after vaccine-introduction (61.1%). Overall, our results showed a post-PCV10 increase in the frequency of serotype 19A. This was accompanied by a selection of CC320 and antimicrobial resistance.

Assessing the efficiency of catch-up campaigns for the introduction of pneumococcal conjugate vaccine: a modelling study based on data from PCV10 introduction in Kilifi, Kenya

BACKGROUND

The World Health Organisation recommends the use of catch-up campaigns as part of the introduction of pneumococcal conjugate vaccines (PCVs) to accelerate herd protection and hence PCV impact. The value of a catch-up campaign is a trade-off between the costs of vaccinating additional age groups and the benefit of additional direct and indirect protection. There is a paucity of observational data, particularly from low- and middle-income countries, to quantify the optimal breadth of such catch-up campaigns.

METHODS

In Kilifi, Kenya, PCV10 was introduced in 2011 using the three-dose Expanded Programme on Immunisation infant schedule and a catch-up campaign in children <5 years old. We fitted a transmission dynamic model to detailed local data, including nasopharyngeal carriage and invasive pneumococcal disease (IPD), to infer the marginal impact of the PCV catch-up campaign over hypothetical routine cohort vaccination in that setting and to estimate the likely impact of alternative campaigns and their dose efficiency.

RESULTS

We estimated that, within 10 years of introduction, the catch-up campaign among children <5 years old prevents an additional 65 (48-84) IPD cases across age groups, compared to PCV cohort introduction alone. Vaccination without any catch-up campaign prevented 155 (121-193) IPD cases and used 1321 (1058-1698) PCV doses per IPD case prevented. In the years after implementation, the PCV programme gradually accrues herd protection, and hence its dose efficiency increases: 10 years after the start of cohort vaccination alone the programme used 910 (732-1184) doses per IPD case averted. We estimated that a two-dose catch-up among children <1 year old uses an additional 910 (732-1184) doses per additional IPD case averted. Furthermore, by extending a single-dose catch-up campaign to children aged 1 to <2 years and subsequently to those aged 2 to <5 years, the campaign uses an additional 412 (296-606) and 543 (403-763) doses per additional IPD case averted. These results were not sensitive to vaccine coverage, serotype competition, the duration of vaccine protection or the relative protection of infants.

CONCLUSIONS

We find that catch-up campaigns are a highly dose-efficient way to accelerate population protection against pneumococcal disease.

Effectiveness of Pneumococcal Conjugate Vaccines of Different Valences Against Invasive Pneumococcal Disease Among Children in Taiwan: A Nationwide Study

BACKGROUND

For the scarcity of data, we investigated the vaccine effectiveness (VE) of the combined use of pneumococcal conjugate vaccines (PCVs) of different valences against invasive pneumococcal disease (IPD) in children.

METHODS

We conducted a matched case-control study using the national IPD surveillance database and the national vaccination registry. Four age-matched, gender-matched and neighborhood-matched controls were identified for each incident IPD case ≦5 years with disease onsets between October 2007 and December 2013. Conditional logistic regression was used to assess VE against all serotype and serotype 19A IPD.

RESULTS

In 523 cases (median age: 28.5 months; range: 2.0-69.4 months) and 2086 controls (28.7; 2.2-70.1), a similar VE against all-serotype IPD was found between PCV13 (76%; 61-85%) and combined 7-valent PCV (PCV7)/10-valent PCV (PCV10) plus PCV13 (78%; 56-89%). The VE for PCV7/PCV10 was slightly lower (48%; 32-60%). Regarding serotype 19A, a significantly reduced risk was observed for both PCV13 (82%; 63-91%) and combined PCV7/PCV10 plus PCV13 (87%; 61-96%). PCV7/PCV10 had only a borderline protective association (31%; 4-51%). For children receiving PCV13 alone, VE against all-serotype IPD did not differ between starting the dosing at ≥2 (78%; 56-89%) or <2 (74%; 51-87%) years of age. VE was 81% (69-88%) within 6 months of the last dose of PCV and 19% (95% CI: -21 to 45%) after 2 years.

CONCLUSIONS

PCVs are effective against IPD during immunization with either the same or with a mixed series, but protection might be differential over time.

10-Valent pneumococcal non-typeable haemophilus influenzae protein D-conjugate vaccine: a review in infants and children

The 10-valent pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) (Synflorix™) includes ten serotype-specific polysaccharides of Streptococcus pneumoniae, eight of which are conjugated individually to a nonlipidated cell-surface lipoprotein (protein D) of non-typeable H. influenzae and two of which are conjugated to nontoxic tetanus or diphtheria toxoid carrier proteins. This article provides an overview of the well-established immunogenicity of PHiD-CV, including functional immune responses and immunologic memory, as well as immune responses in preterm infants and HIV-infected children. It also includes a brief discussion of cross-protection against vaccine-related serotypes (6A and 19A) and focuses on labelling in the EU, where PHiD-CV is approved for active immunization against invasive disease, pneumonia, and acute otitis media (AOM) caused by S. pneumoniae in infants and young children up to 5 years of age. Evidence of the protective efficacy and effectiveness of PHiD-CV against pneumococcal diseases is available from several studies, including the randomized, double-blind trials COMPAS (Clinical Otitis Media and Pneumonia Study) and FinIP (Finnish Invasive Pneumococcal disease), as well as postmarketing studies from various countries. As would be expected, protection against pneumonia or AOM is substantially lower than that against invasive pneumococcal disease, as many micro-organisms other than pneumococcal vaccine serotypes can cause pneumonia and AOM, thereby limiting the overall protection of PHiD-CV against these diseases. PHiD-CV has a safety and reactogenicity profile similar to that of other pneumococcal conjugate vaccines.