H5N1

Flu News Europe: Final report for 2019-20 season

Via Flu News Europe, a wrap-up. Excerpt:

Weeks 21-39/2020 (18 May - 27 September 2020)  

• This is the final report for the 2019-2020 influenza season. 

• Influenza activity has been at inter-seasonal levels over the period of this report.  

• Of 1 523 sentinel specimens tested for influenza viruses in weeks 21-39, 3 tested positive (one each of A(H3N2), B/Victoria lineage and type B no lineage ascribed).   

• The novel coronavirus disease 2019 (COVID-19) pandemic has affected healthcare presentations and testing capacities of Member States in the Region, which negatively impacted reporting of influenza epidemiologic and virologic data. Therefore, the data we present, notably in terms of seasonal patterns, must be interpreted with caution.   

• Weekly reporting for the 2020-2021 influenza season will start in week 40 with the first analysis being published on 10 October 2020. 

Interim estimates of 2019/20 vaccine effectiveness during early-season co-circulation of influenza A and B viruses, Canada, February 2020

Via Eurosurveillance: Interim estimates of 2019/20 vaccine effectiveness during early-season co-circulation of influenza A and B viruses, Canada, February 2020. The abstract:

Interim results from Canada's Sentinel Practitioner Surveillance Network show that during a season characterised by early co-circulation of influenza A and B viruses, the 2019/20 influenza vaccine has provided substantial protection against medically-attended influenza illness. 

Adjusted VE overall was 58% (95% confidence interval (CI): 47 to 66): 44% (95% CI: 26 to 58) for A(H1N1)pdm09, 62% (95% CI: 37 to 77) for A(H3N2) and 69% (95% CI: 57 to 77) for influenza B viruses, predominantly B/Victoria lineage.

Flu News Europe, week 2

Via Flu News Europe, an excerpt from the week 2 update:

Week 02/2020 (6-12 January 2020) 

• Activity increased compared to week 01/2020, particularly in the southern part of the Region, with two Member States reporting high intensity and six reporting medium intensity. The remainder reported baseline or low intensity levels. 

• The percentage of samples from sentinel ILI surveillance patients that tested positive for influenza virus increased from 27% in the previous week to 40% this week. 

• The majority of reported influenza virus detections from sentinel ILI surveillance across the Region for week 02/2020 were type A (67%): this percentage has decreased from a high of 78% in week 49. The distribution of viruses detected varied between Member States and areas and within sub-regions. 

• Data from the 22 countries or regions reporting to the EuroMOMO project indicated that all-cause mortality was at expected levels for this time of the year. 

• ECDC published an Influenza virus characterization report, summarizing surveillance data in Europe through December 2019 

2019/20 season overview  

• For the Region as a whole, influenza activity commenced earlier than previous years. 

• Influenza activity in the European Region, based on sentinel sampling, first exceeded a positivity rate of 10% in week 47/2019 and has remained over 10% for 8 weeks. There has been an overall increasing trend in the weekly positivity rate for influenza virus detections among sentinel ILI surveillance patients, following a dip in week 52. 

• Type A viruses have dominated across the European Region, though several Member States and areas have reported influenza type B virus dominance or co-dominance of types A and B viruses. 

• In sentinel sources, both influenza A subtypes, A(H3N2) and A(H1N1)pdm09, are co-circulating and of the influenza B viruses, the vast majority (98%) have been B/Victoria lineage. 

• Influenzanet, which uses self-reported symptoms for ILI surveillance in the general population of European countries, is included in the bulletin as a pilot for the 2019/2020 season. 

• ECDC and WHO Regional Office published a joint Regional Situation Assessment for the 2019–2020 influenza season up to week 49/2019, which focused on disease severity and impact on healthcare systems to assist forward planning in Member States.

Flu News Europe: Week 1 update

Via Flu News Europe:

Week 01/2020 (30 December 2019-5 January 2020) 

• One Member State reported high intensity activity for the first time this season and three reported medium intensity activity; however, the remainder reported baseline or low intensity levels. 

• The percentage of sentinel ILI surveillance patients positive for influenza virus remains elevated, but has varied in the last three weeks, probably related to under-reporting during the Christmas/New Year period. 

• The majority of reported influenza virus detections from sentinel ILI surveillance across the Region were type A (60%). This percentage has decreased each week from 78% in week 49 but varied between Member States and areas and within sub-regions. 

• Influenzanet, which uses self-reported symptoms for ILI surveillance in the general population of European countries, is included in the bulletin for the first time this week as a pilot. For the last several weeks, activity has been moderate and is currently increasing in the majority of participating countries. 

2019/20 season overview  

• For the Region as a whole, influenza activity commenced earlier than previous years, increasing each week until week 51; since then it has remained elevated but variable. 

• Influenza activity in the European Region, based on sentinel sampling, first exceeded a positivity rate of 10% in week 47/2019 and has remained over 10% for 7 weeks. 

• Type A viruses have dominated across the European Region, although the proportion has been decreasing since week 49 and a number of countries have reported influenza type B virus dominance or co-dominance of types A and B viruses. 

• In sentinel sources, both influenza A subtypes, A(H3N2) and A(H1N1)pdm09, are co-circulating and of the influenza B viruses, the vast majority (97%) have been B/Victoria lineage. 

• ECDC and WHO Regional Office published a joint Regional Situation Assessment of the 2019–2020 influenza season up to week 49/2019, which focuses on disease severity and impact on healthcare systems to assist forward planning in Member States.

US: Flu season may yet turn ugly, CDC warns

Via The New York Times: The Flu Season May Yet Turn Ugly, C.D.C. Warns - The New York Times.

The United States may be headed into a bad flu season, according to figures recently released by the Centers for Disease Control and Prevention. 

As of the last week of December, “widespread” flu activity was reported by health departments in 46 states. More ominously, a second measure — the percentage of patients with flu symptoms visiting medical clinics — shot up almost to the peak reached at the height of the 2017-18 flu season, which was the most severe in a decade.  

About 61,000 Americans died of flu that season, the C.D.C. said. (The original estimate of 79,000 was revised downward last year; the agency said the number changed as more death certificate information became available.)  

This year’s flu vaccine may not be particularly effective against the strain of the virus now widespread in the United States, experts said. But even so, it’s worth getting the shot: people who are vaccinated fare better if struck by the flu than those who are not.

It is still too early to know how severe this season will be, said Lynnette Brammer, leader of the agency’s domestic influenza surveillance team. 

Although many people are coming down with flu, the two chief indicators of severity — hospitalizations and deaths — are not yet elevated, she noted.  

Deaths from pneumonia and flu are actually lower than normal at this time. But reports of hospitalization and death normally lag other indicators by at least two weeks. 

The current season did begin unusually early. By late November, the flu had hit hard in the Deep South, from Texas to Georgia. The virus then broke out in California and the Rocky Mountain states, but was not widespread in the Northeast until recently. 

That pattern echoes what happened in Australia, where winter runs from June through August. Flu came unusually early to the Southern Hemisphere in 2019. In seasons when Australia has a bad flu season, the Northern Hemisphere sometimes does, too.

In another important way, however, the United States is not following Australia’s lead. The A(H3N2) strain of influenza was dominant there last year, while most American cases this season have been caused by a very different strain, called B Victoria. (B strains are named for the cities where they were first isolated.)  

B strain flus do not normally arrive until late in the season. But when they do, “they often impact children more than adults and older adults,” Ms. Brammer said.  

The C.D.C. tracks the deaths of children individually, rather than making estimates, as is done for adults. Those over 65 are usually the group hardest hit by flu. Thus far this season, 27 children have died of flu — in 2017-18, 187 died — but pediatric deaths don’t normally start peaking until mid-January.

Flu News Europe, week 51

Via Flu News Europe:

Week 51/2019 (16-23 December 2019) 

• The majority of reported influenza virus detections across the Region were type A, although 5 countries reported type B virus dominance and 2 reported co-dominance of type A and B viruses. 

• Data from the 21 countries or regions that reported to the EuroMOMO project up to week 50/2019 indicated that all-cause mortality was at expected levels for this time of the year. 

• ECDC and WHO Regional Office published a joint Regional Situation Assessment of the 2019–2020 influenza season up to week 49/2019, which focuses on disease severity and impact on healthcare systems to assist forward planning in Member States. 

2019/20 season overview  

• Influenza activity has increased in the European Region, although most countries still reported influenza activity rates below/at baseline levels or low levels. 

• Influenza activity in the European Region, based on sentinel sampling, first exceeded a positivity rate of 10% in week 47/2019. 

• Type A viruses have dominated across the European Region, although a number of countries reported influenza type B virus dominance or co-dominance of types A and B viruses. 

• In sentinel sources, both influenza A subtypes, A(H3N2) and A(H1N1)pdm09, are co-circulating and of the influenza B viruses, the vast majority (97%) are B/Victoria lineage.

ECDC: Influenza virus characterisation, November 2019

ECDC has published Influenza virus characterisation, November 2019.

This is the second influenza characterisation report for the 2019–20 influenza season. As of week 48/2019, 6 887 influenza detections across the WHO European Region had been reported; of which 84% were type A viruses, with A(H3N2) prevailing over A(H1N1)pdm09, and 16% type B viruses, with 123 of 137 (90%) ascribed to a lineage B/Victoria.

New discovery could spell end to seasonal flu

Via Deutsche Welle: New discovery could spell end to seasonal flu. Excerpt:

A potential breakthrough discovery of new antibodies could lead to a universal vaccine. If successful, it could protect against all types of deadly influenza viruses and even prevent pandemics, a study shows. 

 Immunologist Ali Ellebedy was working on a study analyzing the immune response to flu infection in humans. During his research, he spotted a new type of powerful antibody in a blood sample from a patient infected with human influenza virus.   

Ellebedy then sent samples of the antibody to Florian Krammer — a microbiologist who proved the effectiveness of the antibodies by testing them against extensive samples of virus proteins dating back to the 1970s. These proteins, called neuraminidase, enable the virus to spread through the human body. 

The study, which was jointly conducted by Scripps Research, Washington University's School of Medicine in St. Louis and the Icahn School of Medicine in New York, was published in the October 25 issue of Science.  

Future vaccine could survive antiviral resistance  

Krammer told DW that the beauty of this new antibody, called 10G1, is that it binds to the parts of the virus that never change. This means that even if new strains of influenza viruses are detected, a potential vaccine containing new antibodies would still be effective. 

Moreover, the antibody has a powerful potential to attack both A and B subtypes of influenza viruses, making it an even better candidate for a universal vaccine that would combat human, swine, and bird strains, as well as other rarer strains of lethal flu viruses.

Paradoxical clade- and age-specific vaccine effectiveness during the 2018/19 influenza A(H3N2) epidemic in Canada

Eurosurveillance has published Paradoxical clade- and age-specific vaccine effectiveness during the 2018/19 influenza A(H3N2) epidemic in Canada: potential imprint-regulated effect of vaccine (I-REV). The abstract:

Introduction 

The Canadian Sentinel Practitioner Surveillance Network reports vaccine effectiveness (VE) for the 2018/19 influenza A(H3N2) epidemic. 

Aim 

To explain a paradoxical signal of increased clade 3C.3a risk among 35–54-year-old vaccinees, we hypothesise childhood immunological imprinting and a cohort effect following the 1968 influenza A(H3N2) pandemic.  

Methods 

We assessed VE by test-negative design for influenza A(H3N2) overall and for co-circulating clades 3C.2a1b and 3C.3a. VE variation by age in 2018/19 was compared with amino acid variation in the haemagglutinin glycoprotein by year since 1968.  

Results 

Influenza A(H3N2) VE was 17% (95% CI: −13 to 39) overall: 27% (95% CI: −7 to 50) for 3C.2a1b and −32% (95% CI: −119 to 21) for 3C.3a. Among 20–64-year-olds, VE was −7% (95% CI: −56 to 26): 6% (95% CI: −49 to 41) for 3C.2a1b and −96% (95% CI: −277 to −2) for 3C.3a. Clade 3C.3a VE showed a pronounced negative dip among 35–54-year-olds in whom the odds of medically attended illness were > 4-fold increased for vaccinated vs unvaccinated participants (p < 0.005). This age group was primed in childhood to influenza A(H3N2) viruses that for two decades following the 1968 pandemic bore a serine at haemagglutinin position 159, in common with contemporary 3C.3a viruses but mismatched to 3C.2a vaccine strains instead bearing tyrosine. 

Discussion 

Imprinting by the first childhood influenza infection is known to confer long-lasting immunity focused toward priming epitopes. Our findings suggest vaccine mismatch may negatively interact with imprinted immunity. The immunological mechanisms for imprint-regulated effect of vaccine (I-REV) warrant investigation.

Flu News Europe, week 40

An excerpt from Flu News Europe:

Week 40/2019 (30 September– 6 October 2019) 

• This is the first weekly report for the 2019–2020 influenza season. 

• Influenza activity was low throughout the European Region. Influenza viruses were detected sporadically in specimens from persons with respiratory illness presenting to medical care. 

• Both influenza A and B type viruses were detected. 

• For week 40/2019, data from the 21 countries or regions reporting to the EuroMOMO project indicated all-cause mortality to be at expected levels for this time of the year. 

2018/19 season overview  

• As is usual for this time of year, influenza activity is low in the European Region. 

• During the influenza Vaccine Composition Meeting for the southern hemisphere 2020 season, held in September 2019, WHO recommended the A(H1N1)pdm09 component to be an A/Brisbane/02/2018 (H1N1)pdm09-like virus, the A(H3N2) component an A/South Australia/34/2019 (H3N2)-like virus and the B/Victoria-lineage component to be a B/Washington/02/2019-like virus. The B/Yamagata-lineage component, included only in quadrivalent vaccines is a B/Phuket/3073/2013-like virus. The full report can be found here.