A late sharp increase in influenza detections and low interim vaccine effectiveness against the circulating A(H3N2) strain, Denmark, 2021/22 influenza season up to 25 March 2022

Emborg, Hanne‐Dorthe; Vestergaard, Lasse S; Botnen, Amanda Bolt; Nielsen, Jens; Krause, Tyra Grove; Trebbien, Ramona

doi:10.2807/1560-7917.es.2022.27.15.2200278

Cited by 34 publications

(34 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These IVE estimates were slightly higher than the in-season ones reported from Denmark and the United States [ 3 , 4 ]. All influenza A(H3N2) viruses characterised in the 2021/22 season in Navarre were A/Bangladesh/4005/2020-like (3C.2a1b.2a.2), which did not match the A/Cambodia/e0826360 (3C.2a1b.2a.1) vaccine component [ 7 ].…”

Section: Discussioncontrasting

confidence: 63%

“…Interestingly, our results also show that people vaccinated in previous seasons but not in the current season could retain some level of protection that reached statistical significance in the February-May period. These IVE estimates were slightly higher than the inseason ones reported from Denmark and the United States [3,4]. All influenza A(H3N2) viruses characterised in the 2021/22 season in Navarre were A/ Bangladesh/4005/2020-like (3C.2a1b.2a.2), which did not match the A/Cambodia/e0826360 (3C.2a1b.2a.1) vaccine component [7].…”

Section: Discussionmentioning

confidence: 95%

“…The influenza season 2021/22 in Spain and Europe was characterised by low incidence of cases, long duration, predominance of influenza A(H3N2), and sporadic circulation of influenza A(H1N1)pdm09 and B/Victoria viruses [ 1 , 2 ]. While interim estimates from Denmark and the United States showed a low influenza vaccine effectiveness (IVE) against influenza A(H3N2) virus at primary care level [ 3 , 4 ], the end of season IVE still needs to be determined. It also remains to be established if vaccination in previous influenza seasons modified the IVE.…”

mentioning

confidence: 99%

“…Against influenza A(H3N2), estimates were 39% (95% CI: 16 to 55) and 24% (95% CI: −8 to 47) suggesting moderate effectiveness of current season vaccination and possible remaining effect of prior vaccinations.The influenza season 2021/22 in Spain and Europe was characterised by low incidence of cases, long duration, predominance of influenza A(H3N2), and sporadic circulation of influenza A(H1N1)pdm09 and B/Victoria viruses [1,2]. While interim estimates from Denmark and the United States showed a low influenza vaccine effectiveness (IVE) against influenza A(H3N2) virus at primary care level [3,4], the end of season IVE still needs to be determined. It also remains to be established if vaccination in previous influenza seasons modified the IVE.We aimed to estimate the effectiveness of the influenza vaccinations received in the current and previous seasons in preventing laboratory-confirmed influenza among patients attending primary care in the 2021/22 season.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Effectiveness of influenza vaccination in preventing influenza in primary care, Navarre, Spain, 2021/22

et al. 2022

View full text Add to dashboard Cite

Compared with individuals unvaccinated in the current and three previous influenza seasons, in 2021/22, influenza vaccine effectiveness at primary care level was 37% (95% CI: 16 to 52) for current season vaccination, regardless of previous doses, and 35% (95% CI: −3 to 45) for only previous seasons vaccination. Against influenza A(H3N2), estimates were 39% (95% CI: 16 to 55) and 24% (95% CI: −8 to 47) suggesting moderate effectiveness of current season vaccination and possible remaining effect of prior vaccinations.

show abstract

Section: Discussioncontrasting

confidence: 63%

Section: Discussionmentioning

confidence: 95%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Effectiveness of influenza vaccination in preventing influenza in primary care, Navarre, Spain, 2021/22

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Loss of exposure to the influenza virus may lead to more severe waves or out of season waves [6,7] and may increase the susceptible pool, especially in children. Already, influenza circulation was typically late in Europe as of spring 2022 [42]. Other epidemiological changes could occur regarding the exposed population and the seeding from the tropics [30] as global air transportation resumes.…”

Section: Discussionmentioning

confidence: 99%

Global patterns and drivers of influenza decline during the COVID-19 pandemic

Bonacina

Boëlle

Colizza

et al. 2022

Preprint

View full text Add to dashboard Cite

Influenza circulation declined during the COVID-19 pandemic. The timing and extent of decline and its association with interventions against COVID-19 were described for some regions. Here, we provide a global analysis of the influenza decline between March 2020 and September 2021 and investigate its potential drivers. We computed influenza change by country and trimester relative to the 2014-2019 period using the number of samples in the FluNet database. We used random forests to determine important predictors in a list of 20 covariates including demography, weather, pandemic preparedness, COVID-19 incidence, and COVID-19 pandemic response. With a regression tree we then classified observations according to these predictors. We found that influenza circulation decreased globally, with COVID-19 incidence and pandemic preparedness being the two most important predictors of this decrease. The regression tree showed interpretable groups of observations by country and trimester: Europe and North America clustered together in spring 2020, with limited influenza decline despite strong COVID-19 restrictions; in the period afterwards countries of temperate regions, with high pandemic preparedness, high COVID-19 incidence and stringent social restrictions grouped together having strong influenza decline. Conversely, countries in the tropics, with altogether low pandemic preparedness, low reported COVID-19 incidence and low strength of COVID-19 response showed low influenza decline overall. A final group singled out four "zero-Covid" countries, with the lowest residual influenza levels. The spatiotemporal decline of influenza during the COVID-19 pandemic was global, yet heterogeneous. The sociodemographic context and stage of the COVID-19 pandemic showed non-linear associations with this decline. Zero-Covid countries maintained the lowest levels of reduction with strict border controls and despite close-to-normal social activity. These results suggest that the resurgence of influenza could take equally diverse paths. It also emphasizes the importance of influenza reseeding in driving countries' seasonal influenza epidemics.

show abstract

Low prevalence of influenza viruses and predominance of A(H3N2) virus with respect to SARS‐CoV‐2 during the 2021–2022 season in Bulgaria

Korsun

Trifonova

Dobrinov

et al. 2023

Journal of Medical Virology

View full text Add to dashboard Cite

Social distancing, mask-wearing, and travel restrictions during the COVID-19 pandemic have significantly impacted the spread of influenza viruses. The objectives of this study were to analyze the pattern of influenza virus circulation with respect to that of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Bulgaria during the 2021-2022 season and to perform a phylogenetic/molecular analysis of the hemagglutinin (HA) and neuraminidase (NA) sequences of representative influenza strains. Influenza infection was confirmed using real-time reverse transcription polymerase chain reaction in 93 (4.2%) of the 2193 patients with acute respiratory illness tested wherein all detected viruses were subtyped as A (H3N2). SARS-CoV-2 was identified in 377 (24.3%) of the 1552 patients tested.Significant differences in the incidence of influenza viruses and SARS-CoV-2 were found between individual age groups, outpatients/inpatients, and in the seasonal distribution of cases. Two cases of coinfections were identified. In hospitalized patients, the C t values of influenza viruses at admission were lower in adults aged ≥65 years (indicating higher viral load) than in children aged 0-14 years (p < 0.05). In SARS-CoV-2-positive inpatients, this association was not statistically significant. HA genes of all A(H3N2) viruses analyzed belonged to subclade 3C.2a1b.2a.The sequenced viruses carried 11 substitutions in HA and 5 in NA, in comparison to the vaccine virus A/Cambodia/e0826360/2020, including several substitutions in the HA antigenic sites B and C. This study revealed extensive changes in the typical epidemiology of influenza infection, including a dramatic reduction in the number of cases, diminished genetic diversity of circulating viruses, changes in age, and seasonal distribution of cases.

show abstract

A late sharp increase in influenza detections and low interim vaccine effectiveness against the circulating A(H3N2) strain, Denmark, 2021/22 influenza season up to 25 March 2022

Cited by 34 publications

References 6 publications

Effectiveness of influenza vaccination in preventing influenza in primary care, Navarre, Spain, 2021/22

Effectiveness of influenza vaccination in preventing influenza in primary care, Navarre, Spain, 2021/22

Global patterns and drivers of influenza decline during the COVID-19 pandemic

Low prevalence of influenza viruses and predominance of A(H3N2) virus with respect to SARS‐CoV‐2 during the 2021–2022 season in Bulgaria

Contact Info

Product

Resources

About