A31 Diversity change of influenza A (H3N2) strains circulating in Brazil during 2017–8: What to expect in the coming winter?
Bibliographic record
Abstract
Abstract The H3N2 subtype of influenza A (H3N2) was the predominant strain during the early months of the 2017 influenza epidemic in Brazil. In Australia, it was responsible for a strong and prolonged 2017 season and reached the Northern hemisphere causing an intense 2017/8 influenza season. Several genetic and antigenic A(H3N2) variants were circulating, which made the decision about which strain to incorporate into the influenza vaccine challenging. For 2018, the WHO selected a new H3N2 strain, A/Singapore/INFIMH-16-0019/2016-like, to replace the strain A/HongKong/4801/2014-like in the Southern Hemisphere trivalent vaccine. The aim of this study was to describe the genetic diversity of influenza A (H3N2) viruses circulating in Brazil between January 2017 and January 2018, checking the match between the vaccines and worldwide circulating strains with the Brazilian influenza strains. Hemagglutinin gene sequencing of the influenza A (H3N2) was performed, followed by a phylogenetic reconstruction using additional database sequences to define genetic groups and compare with other worldwide circulating strains. We observed a large diversity of H3N2 genetic clusters, including 3C.2a, 3C.2a1, 3C.3a, and their subgroups. During the 2016–7, inter-epidemic and 2017 epidemic period the cluster most frequently detected belonged to clade 3C.2a1 (148/185; 80.0%), a distinct group related to the 2017 vaccine strain A/HongKong/4801/2014-like (3C.2a). However, the genetic profile changed during the study period and in the inter-epidemic season 2017–8 the most commonly detected genetic group was the 3C.2a cluster (43/58; 74.1%). Inside this cluster, the majority (34/43; 79.1%) of strains belonged to a single genetic 3C.2a subgroup 2 (3C.2a2), bearing antigenic substitutions T131K and R142K (site A) and R261Q (site E). The dominance of this 3C.2a2 in the 2017–8 inter-epidemic period in Brazil was similar to the 2017–8 season in Europe and Canada according their surveillance data. The new vaccine strain has five to six antigenic changes in comparison to the predominant 3C.2a2 circulating in South America since September 2017 until now. It is possible that the vaccine mismatch will not protect the population against a majority of circulating strains. Surveillance of the vaccine effectiveness supported by antigenic and serological analysis are necessary to prove this hypothesis. However, this highlights the difficulty of vaccine strain selection and highlights the need for of a universal influenza vaccine.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".