Seroconversion to Seasonal Influenza Viruses after A(H1N1)pdm09 Virus Infection, Quebec, Canada
Bibliographic record
Abstract
We looked for cross-reactive antibodies in 122 persons with paired serum samples collected during the 2009 pandemic of infl uenza virus A(H1N1)pdm09.Eight (12%) of 67 persons with A(H1N1)pdm09 infection confi rmed by reverse transcription PCR and/or serology also seroconverted to the seasonal A/Brisbane/59/2007 (H1N1) virus, compared with 1 (2%) of 55 A(H1N1)pdm09-negative persons (p<0.05).T he role of seasonal 2008-09 trivalent inactivated infl uenza vaccines in protecting against infl uenza A(H1N1)pdm09 virus remains controversial (1).Recent reports indicated that prior infections with seasonal infl uenza A viruses protected against A(H1N1)pdm09 virus infection, suggesting the presence of cross-reactive antibodies (2).Several studies have proposed that humoral immunity and conserved B-and T-cell epitopes contribute to heterosubtypic protection (3,4).Our objective was to determine whether A(H1N1)pdm09 infection induced cross-reactive antibodies against seasonal infl uenza A (H1N1) and A (H3N2) viruses. The StudyThis investigation was part of a trial evaluating A(H1N1)pdm09 transmission among household contacts, conducted during the fi rst wave of the 2009 pandemic (May-July 2009) in Quebec City, Quebec, Canada (5).Clinical data and samples were serially obtained from index case-patients and their contacts in 42 households.Nasopharyngeal secretions were collected from all participants during the fi rst visit and tested by 2 different assays: a conventional reverse transcription PCR (RT-PCR) targeting the hemagglutinin gene of A(H1N1)pdm09 virus ( 6) and a universal RT-PCR targeting the matrix gene of all infl uenza A viruses (7).Blood was collected from persons >7 years of age at their initial visit (acute-phase sample) and 3-4 weeks later (convalescent-phase sample).Serum was tested by microneutralization assay according to World Health Organization standard protocols with minor modifi cations (8).This serologic study comprised 122 persons from the 42 households.Twenty-four persons were RT-PCRconfi rmed index case-patients (median age 15 years, range 7-56 years), and 98 were household contacts (median age 30.5 years, range 7-61 years), of whom 34 also were positive for A(H1N1)pdm09 virus by RT-PCR.For 67 patients (median age 20 years, range 7-61 years), A(H1N1)pdm09 was confi rmed by RT-PCR and/ or microneutralization assay: 10 (15%) by RT-PCR alone, 9 (13%) by microneutralization assay alone, and 48 (72%) by RT-PCR and microneutralization assay.Of the 67 A(H1N1)pdm09-infected persons, 8 (12%) seroconverted to A/Brisbane/59/2007 (A[H1N1] vaccine strain for 2008-09) (online Appendix Table, wwwnc.cdc.gov/EID/article/18/7/11-1680-TA1.htm).Seven A/ Brisbane/59/2007 seroconverters were RT-PCR positive and A(H1N1)pdm09 seroconverters, and 1 was RT-PCR positive and a A(H1N1)pdm09 nonseroconverter.In comparison, 1 (2%) of the 55 A(H1N1)pdm09-negative patients seroconverted to A/Brisbane/59/2007 (Fisher exact test, p<0.05).Seasonal infl uenza viruses were not circulating in the province of Quebec at the time of this study.Only 1 of 9 A/Brisbane/59/2007 seroconverters had previously received the inactivated 2008-09 seasonal infl uenza vaccines.No participants were vaccinated against A(H1N1)pdm09 virus, and none received antiviral therapy or prophylaxis.We then assessed whether this cross-reactivity was limited to the A/Brisbane/59/2007 strain, the most recent seasonal A (H1N1) virus to have circulated before A(H1N1)pdm09 virus, or whether it was broader.To this end, we tested all paired serum samples against an older seasonal A (H1N1) infl uenza virus, i.e., A/New Caledonia/20/1999 (H1N1 vaccine strain used during the 2000- 01 through 2006-07 seasons), and a past A(H3N2) virus, i.e., A/Panama/7/2004 (H3N2 vaccine component used during the 2000-01 through 2003-04 seasons).Seven (10%) A(H1N1)pdm09 virus-positive persons also seroconverted to A/New Caledonia/20/1999(H1N1), all of
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".