Pertactin deficiency of <i>Bordetella pertussis</i>: Insights into epidemiology, and perspectives on surveillance and public health impact
Bibliographic record
Abstract
Pertussis resurgence has been documented even in countries with high pediatric vaccine coverage. The proportion of Bordetella pertussis isolates not expressing pertactin (PRN) has increased in several countries where acellular pertussis (aP) vaccines are used. We systematically reviewed published literature up to July 2023 on PRN-negative B. pertussis isolates in MEDLINE and Embase with no geographical limitations, complemented with a gray literature search. An increase in the proportion of PRN-negative isolates was observed in countries where aP vaccines were used, while such isolates seem to be absent in countries using whole-cell pertussis vaccination. We reviewed the data supporting aP vaccine-driven evolution of B. pertussis, explored the effects of PRN deficiency on the clinical presentation of pertussis, summarized the evidence for preserved aP vaccine effectiveness, and proposed actions to further improve assessment of the clinical significance of PRN deficiency and its potential impact on pertussis prevention. The burden of pertussis (whooping cough), once a common cause of morbidity and mortality among children, was greatly reduced by the introduction of pediatric pertussis vaccination. Two types of pertussis vaccines exist: whole-cell pertussis (wP) vaccines, containing inactivated Bordetella pertussis bacteria, and acellular pertussis (aP) vaccines, containing purified antigens. Having lower reactogenicity, aP vaccines have replaced wP vaccines in many developed countries. In other parts of the world, wP vaccines are still used. Over time, the proportion of B. pertussis isolates not expressing pertactin (PRN, a surface antigen involved in virulence and contained in most aP vaccines) increased in countries using aP vaccines, but not in those using only wP vaccines. We performed a systematic literature review to collect data on the epidemiology of PRN-negative B. pertussis isolates identified worldwide. We combined these data with information on the type of pertussis vaccine used in each country and on the year aP vaccines were introduced, to assess if aP vaccine use was associated with a higher proportion of PRN-negative B. pertussis strains. We then selected three countries (Belgium, France, and Canada), for which we present data on pertussis diagnosis, surveillance, epidemiology, pertussis vaccine recommendations, and vaccine coverage, in connection with the PRN-negative B. pertussis data retrieved by our search. We found that the symptoms and severity of pertussis cases appear to be similar regardless of whether they were caused by PRN-negative or PRN-positive strains. There is no evidence of impaired protection by aP vaccines in countries where most circulating B. pertussis strains are PRN-negative.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.007 | 0.019 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.008 | 0.009 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.003 | 0.003 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".