Friday, February 23, 2018

FluView Week 7: Influenza Activity Remains Elevated Across The United States


Week 7 ILI Outpatient Visits Still Very High

















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While influenza activity appears to be backing off the record highs reported two weeks ago, the number of visits for ILI (influenza-like illness) remains very high (see chart above), and continues to exceed all of the peaks reported since the H1N1 pandemic of 2009.

Influenza related hospitalizations continue to soar, beating the end-of-season totals from the past 6 seasons handily (see mashup chart below), with several weeks of flu season to go.

The 2014-15 season was estimated to have seen around 700,000 hospitalizations, and while we have no totals yet, this year looks to exceed that number by a pretty good margin. 
Worst affected have been those aged 65+ (322.7 per 100,000 population), followed by adults aged 50-64 (79.9 per 100,000 population) and children aged 0-4 years (52.6 per 100,000 population).
P&I Mortality numbers have dropped a bit (see below), but there continue to be data collection delays, and the final numbers are apt to see adjustment upward.  

https://www.cdc.gov/flu/weekly/


The number of pediatric deaths (often a lagging indicator) jumped by another 13 cases, with several being delayed reports from earlier in the season.

https://www.cdc.gov/flu/weekly/

While H3N2 continues to hold the lead, as the season progresses we continue to see both influenza B and H1N1 making gains.  

https://www.cdc.gov/flu/weekly/ 



We continue to see some states - particularly in the west - report a reduction in ILI activity (see map below), although most of the country remains in the grip of the grippe.
https://www.cdc.gov/flu/weekly/

Some highlights from a much more detailed FluView include:

2017-2018 Influenza Season Week 7 ending February 17, 2018

All data are preliminary and may change as more reports are received.
Synopsis:

During week 7 (February 11-17, 2018), influenza activity remained elevated in the United States.
Viral Surveillance: The most frequently identified influenza virus subtype reported by public health laboratories during week 7 was influenza A(H3). The percentage of respiratory specimens testing positive for influenza in clinical laboratories remained elevated.
Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was above the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
Influenza-associated Pediatric Deaths: Thirteen influenza-associated pediatric deaths were reported.
Influenza-associated Hospitalizations: A cumulative rate of 74.5 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
Outpatient Illness Surveillance:The proportion of outpatient visits for influenza-like illness (ILI) was 6.4%, which is above the national baseline of 2.2%. All 10 regions reported ILI at or above region-specific baseline levels. New York City, the District of Columbia, Puerto Rico and 39 states experienced high ILI activity; five states experienced moderate ILI activity; three states experienced low ILI activity; and three states experienced minimal ILI activity.
Geographic Spread of Influenza:The geographic spread of influenza in Puerto Rico and 48 states was reported as widespread; the District of Columbia, Guam and two states reported local activity; and the U.S. Virgin Islands reported no activity.
 As always, it isn't too late to get the flu shot.  And with influenza B and H1N1 rising, it could still offer some valuable protection.  But most of all, now is the time to practice good flu hygiene. 
Stay home if you are sick, avoid crowds, wash your hands frequently, and cover your coughs and sneezes. 
While we may have passed the peak of this flu season, there is undoubtedly a good deal of flu in store for the next few weeks, and the numbers will continue to come in for weeks after that.

EID Journal: Multiple Introductions Of HPAI H5N8 In Egypt

Credit EID Journal
https://wwwnc.cdc.gov/eid/article/24/5/17-1935-f1













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After starting out as an exclusively Chinese and Southeast Asian problem early in the last decade, avian HPAI H5 viruses have spread globally via migratory birds - and while many areas outside of Asia have been affected - no region has reported as much consistent HPAI H5 activity over the past decade as Egypt and the Middle East. 
Despite this, we see relatively few in-depth reports on avian flu viruses coming from that part of the world, and when we do, it is nearly always from Egypt.
Often the reporting of avian flu outbreaks to the OIE is either fragmented, belated, or - far too often -  simply not done by many countries in the Middle East (and elsewhere).  
Admittedly, for many nations, this may be due to the remote location of outbreaks, the reluctance of farmers to report poultry deaths, or a lack of resources.
Even novel human infections may go undetected or reported, with only about 1/3rd of the countries of the world currently self-reporting they have met the core requirements of the 2005 International Health Regulations (see Adding Accountability To The IHR).
The unfortunate result is - at least compared to Europe, North America, and parts of Asia - we don't really have a good handle on what novel viruses are circulating in many places around the globe, or what changes may be occurring in them.
Today, however, we have a Research Letter appearing in the EID Journal that gives us some valuable new insight on the late 2016 arrival, and subsequent multiple introductions of HPAI H5N8, to Egypt during 2017.
Of particular note, four genetically distinct H5N8 viruses were characterized, and all carried previously identified mammalian-adaptation and virulence markers (see Evaluation of phenotypic markers in full genome sequences of avian influenza isolates from California) that raise potential public health concerns.
I've only included some extracts from the letter (bolding mine), so follow the link to read it in its entirety.  I'll return with a brief postscript. 

Volume 24, Number 5—May 2018
Research Letter


Multiple Introductions of Influenza A(H5N8) Virus into Poultry, Egypt, 2017

Ahmen H. Salaheldin, Hatem Salah Abd El-Hamid, Ahmed R. Elbestawy, Jutta Veits, Hafez M. Hafez, Thomas C. Mettenleiter, and Elsayed M. Abd El-Whab


Abstract

After high mortality rates among commercial poultry were reported in Egypt in 2017, we genetically characterized 4 distinct influenza A(H5N8) viruses isolated from poultry. Full-genome analysis indicated separate introductions of H5N8 clade 2.3.4.4 reassortants from Europe and Asia into Egypt, which poses a serious threat for poultry and humans.

In Egypt, highly pathogenic avian influenza A(H5N1) clade 2.2.1 virus was introduced to poultry via migratory birds in late 2005 (1) and is now endemic among poultry in Egypt (2).
Also in Egypt, the number of H5N1 infections in humans is the highest in the world, and low pathogenicity influenza A(H9N2) virus is widespread among poultry and has infected humans (2).
Despite extensive vaccination, H5N1 and H9N2 viruses are co-circulating and frequently reported (2). In 2014, highly pathogenic avian influenza A(H5N8) virus clade 2.3.4.4 was isolated, mostly from wild birds, in several Eurasian countries and was transmitted to North America. However, in 2016 and 2017, an unprecedented epidemic was reported in Asia, Africa, and Europe (3).
In Egypt, during November 30–December 8, 2016, a total of 3 H5N8 viruses were isolated from common coot (Fulica atra) (4) and green-winged teal (Anas carolinensis) (5). To provide data on the spread of the virus in poultry, we genetically characterized 4 distinct H5N8 viruses isolated from commercial poultry in Egypt in 2017.
(SNIP)

The hemagglutinin (HA) and neuraminidase (NA) genes of the 4 viruses shared 95.8%–99.2% nt and 93.1%–99.4% aa identity and shared 96.5%–99.2% nt and 94.2%–99.7% aa identity with viruses from wild birds in Egypt (4,5). Other segments showed 92.6%–99.6% nt and 96%–99.7% aa identity, where the polymerase acidic (PA) genes and proteins of viruses from Dk18 showed the lowest similarity to those of other viruses (Technical Appendix 1[PDF - 1.22 MB - 5 pages] Figure 1).

All viruses possess the polybasic HA cleavage site PLREKRRKR/G and contain mammal-adaptation and virulence markers (9) in polymerase basic (PB) 2 (T63I, L89V, G309D, T339K, Q368R, H447Q, R477G), PB1 (A3V, L13P, K328N, S375N, H436Y, M677T), PA (A515T), HA (T156A, A263T; H5 numbering), matrix (M) 1 (N30D, T215A), and nonstructural (NS) 1 (P42S, T127N, V149A) proteins.
Therefore, protection of humans and risk assessment of bird-to-human transmission is crucial.
(SNIP)
These data suggest 4 different introductions of H5N8 virus into poultry in Egypt, independent of viruses isolated from captive birds (4,5). Multiple separate introductions of H5N8 virus into Europe also occurred (10). Further studies are needed to identify the source(s) of introduction. The separate introductions of different reassortants of H5N8 clade 2.3.4.4 virus from Europe and Asia into Egypt indicates a serious threat for poultry and human health.

Mr. Salaheldin is a doctoral student at the Institute of Poultry Diseases, Freie-Universit├Ąt-Berlin. His main interests are molecular virology, vaccine development, and epidemiology of avian influenza viruses.


Thus far HPAI H5N8 (and it's reassorted progenies H5N6 & H5N6) have shown few signs of infecting mammals and no human infections have been reliably reported.

We did see early reports out of South Korea in 2014 of dogs having been infected (see MAFRA: H5N8 Antibodies Detected In South Korean Dogs (Again)) and less than a year ago saw J. Vet. Sci.: Experimental Canine Infection With Avian H5N8.
So we know that mammalian infection with at least some genotypes of H5N8 is at least possible.
Over the past year we've looked at a number of studies that have explored the potential for H5N8 or its spinoffs to evolve into a human health threat. A few include:
J Vet Sci: Evolution, Global Spread, And Pathogenicity Of HPAI H5Nx Clade 2.3.4.4 
Study: Virulence Of HPAI H5N8 Enhanced By 2 Amino Acid Substitutions

Sci Rpts: H5N8 - Rapid Acquisition of Virulence Markers After Serial Passage In Mice 
Perhaps most telling of these came last September in J. Virulence : Altered Virulence Of (HPAI) H5N8 Reassortant Viruses In Mammalian Models, which found:
Taken together, our study demonstrates that a single gene substitution from other avian influenza viruses can alter the pathogenicity of recent H5N8 viruses, and therefore emphasizes the need for intensive monitoring of reassortment events among co-circulating avian and mammalian viruses.
Last October's J. Virulence Editorial: HPAI H5N8 - Should We Be Worried? reviewed and summarized the literature, and found enough reasons to be concerned over the future evolutionary path of H5N8, stating that:
The extensive distribution of HPAI H5N8, as well as the gene reassortment with other circulating avian viruses already observed for H5N8 suggests there is a potential risk for human cases of H5N8 infections.
While none of this means there is a human adapted H5N8 virus in our future, considering the continual evolution of the virus - particularly in areas of the world where we have little or no visibility - we can't ignore the possibility of someday being blindsided by an abrupt change in the virus's behavior.

Making studies like this one particularly valuable.

NEJM: Flu Season A Risk Factor For Developing Post-Cardiac Surgery ARDS












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ARDS (Acute Respiratory Distress Syndrome) is a rapidly progressing - often life-threatening complication - hallmarked by the leaking of fluid into the small air sacs (alveoli) of the lungs, usually as the result of a direct or indirect lung injury.
ARDS can be caused by a variety of insults to the lung, including aspiration, chemical or smoke inhalation, pneumonia, septic shock, or trauma.  It is often seen in critically ill patients with liver of kidney failure.
With the build up of fluids from ARDS, the patient is unable to pass oxygen efficiently  through their lung's alveoli into the the bloodstream, even when placed on a ventilator.
Low oxygen levels (hypoxia) can lead to further organ damage and even death.
ARDS is most often observed in patients already hospitalized for another serious illness, and while survival rates vary depending on age, the underlying cause, and comorbidities  - some estimates put the mortality rate somewhere between 33%-50%.

As the following excerpt from the 2016 study (Acute respiratory distress syndrome following cardiovascular surgery: current concepts and novel therapeutic approaches) explains, ARDS is a rare, but serious complication following cardiac surgery.

Cardiac surgery is a known risk factor for ARDS, especially when using cardiopulmonary bypass (CPB), because CPB induces a systemic inflammatory response and pulmonary ischemia-reperfusion injury. Today more high-risk patients undergo cardiac surgical interventions and an increasing number of patients is provided with complex procedures [2,3].
To date there are eight clinical studies that analyzed the incidence, risk factors, and mortality of ARDS following cardiac surgery (overview in [4▪]). The incidence of ARDS varied from 0.17 to 2.5% and mortality from 15 to 91.6%.

Yesterday the NEJM published a correspondence which suggests that post-cardiac surgery ARDS complications may occur more frequently during flu season, even when the patient shows no signs of influenza infection.

Influenza Season and ARDS after Cardiac Surgery

February 22, 2018
N Engl J Med 2018; 378:772-773
DOI: 10.1056/NEJMc1712727

To the Editor:

A number of concurrent risk factors are associated with development of the acute respiratory distress syndrome (ARDS). One such risk factor might be asymptomatic respiratory viral infection — for example, influenza — which could prime the lungs for ARDS in patients with another overt risk factor. Patients who undergo cardiac surgery could potentially carry these viruses yet have no clinical signs or symptoms.1
(Continue . . . )

The correspondence, along with a 24-page Supplementary Appendix, continue on to describe a two-year single-center observational cohort study on cardiac patients at the ICU of a tertiary university hospital in the Netherlands.
While patients were not tested for flu, the study found that the incidence of ARDS complications following cardiac surgery doubled during flu season, even though the surgical patients showed no signs of respiratory infection before surgery.
 In the discussion section of the supplemental file, the authors wrote:
Cardiac surgery during influenza season is an independent risk factor for development of postoperative ARDS compared to surgery during seasons with little respiratory virus transmission.

The main finding of the present study is that the risk for the development of ARDS after  cardiac surgery is about twice increased during the influenza season as compared to seasons with low burden of respiratory virus infections.
Moreover, the influenza season did increase the duration of mechanical ventilation. The influenza season was estimated on the basis of weekly reporting of influenza-like illness within the community by sentinel surveillance at general practitioner offices, confirmed by detecting influenza in nasopharyngeal samples.
On multivariate modelling, the influenza season proved to be an independent risk factor for the development of ARDS postoperatively, besides well known factors like EuroSCORE and total time on CPB.

Of note, the 2009 pandemic fell within the study period. 

Since influenza tests (or other respiratory panels) were not conducted, the authors point out that they haven't proven that an underlying viral infection causes increased ARDS in cardiac surgery patients. They wrote:
Our study also has several weaknesses. First and for all, our cohort study shows an association but does not prove a causal relation between viral infection and ARDS in cardiac surgery patients. There are potential confounders that vary by season, such as vitamin D level or ambient temperature, for which we could not adjust.
Still, if confirmed by other studies, this research raises interesting questions about the potential value of pre-surgical testing for viral infection, even when a patient appears to be asymptomatic.

Thursday, February 22, 2018

WHO Update & Risk Assessment On Avian H7N4

Jiangsu Province - Credit Wikipedia













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Just a little over a week after the initial announcement from China of the first known human infection with an avian H7N4 virus, we are starting to get details about both the patient and the virus, with a genetic characterization released earlier today (see WHO: Genetic Characteristics Of Avian H7N4).
The World Health Organization has also just released their first update, and a preliminary risk assessment on this emerging virus.  
While additional human cases are possible, the lack of infection among 28 close contacts to the first case is encouraging. We will, of course, be anxious to get further information about this virus, including the results of ferret transmission studies, and its prevalence in poultry.

Human infection with avian influenza A(H7N4) virus – China

Disease outbreak news
22 February 2018

On 14 February 2018, the National Health and Family Planning Commission (NHFPC) of China notified the World Health Organization (WHO) of one case of human infection with avian influenza A(H7N4) virus. This is the first human case of avian influenza A(H7N4) infection to be reported worldwide.

The case-patient was a 68-year-old woman from Jiangsu Province with pre-existing coronary heart disease and hypertension and she developed symptoms on 25 December 2017. Seven days later, she was admitted to a local hospital for treatment of severe pneumonia and was discharged after 21 days. On 12 February, the Chinese Center for Disease Control and Prevention (China CDC) confirmed that the case-patient’s samples were positive for avian influenza A(H7N4). The NHFPC confirmed the diagnosis on 13 February 2018. The case-patient had reported a history of exposure to live poultry before onset of symptoms.

Genetic sequencing of this A(H7N4) virus shows that all the virus segments originated from avian influenza viruses. This virus is sensitive to adamantanes and neuraminidase inhibitors based on genetic sequencing.

Twenty-eight close contacts of the case-patient have been under medical observation. Among close contacts, no abnormal findings have been found and all throat swabs from her contacts have tested negative.
Public health response

The Chinese government conducted a risk assessment, and has enhanced prevention and control measures, surveillance and epidemiological investigations including contact tracing and laboratory testing. Public risk communication and information sharing is ongoing.

WHO is in contact with national authorities and is following the event closely. WHO is facilitating information-sharing with Member States and is closely monitoring the situation, in line with the International Health Regulations (2005).
WHO risk assessment

This is the first report of a human case of avian influenza A(H7N4) infection globally and the case reported exposure to live backyard poultry before illness onset. Genetic analysis of this influenza A(H7N4) virus indicates that it is of avian origin.

Close contacts of the case-patient tested negative for avian influenza A(H7N4) and remained asymptomatic. Current evidence suggests that this virus does not have the ability of sustained transmission to humans, thus the likelihood of sustained human to human transmission is low. Any animal influenza virus that develops the ability of human to human transmission can theoretically cause a pandemic.

It is possible that additional human cases of avian influenza A(H7N4) will be detected, however only one human case has been detected so far, and information on the circulation of avian influenza A(H7N4) in birds is not currently available. Further information needs to be gathered to increase the confidence in this assessment.
WHO advice

The public should avoid contact with high-risk environments such as live animal markets/farms and live poultry, or surfaces that might be contaminated by poultry feces. Hand hygiene with frequent washing or use of alcohol hand sanitizer is recommended. WHO does not recommend any specific different measures for travellers.

WHO does not advise special screening at points of entry with regard to this event, nor does it recommend that any travel or trade restrictions be applied.

Hong Kong Flu Express Wk 7: Flu Remains At A High Level

https://www.chp.gov.hk/files/pdf/fluexpress_week07_22_02_2018_eng.pdf















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Although there are some hopeful signs that flu may have finally peaked in Hong Kong, influenza activity remains at a high level, and local schools will resume classes next week after an extended closing for flu and the New Year's Holiday. 

Today's hospital Occupancy report (below) shows a 5% drop over Tuesday's post-holiday 119% peak, although admissions yesterday were still running about 150 over the average for this time of year.

http://gia.info.gov.hk/general/201802/22/P2018022200211_278675_1_1519262992358.pdf


Even with all schools having been closed for two weeks, institutional outbreaks continue to outpace any flu season in recent memory, no doubt inspiring an announcement today from the CHP Public urged to continue their vigilance against influenza as school will soon resume.

https://www.chp.gov.hk/files/pdf/fluexpress_week07_22_02_2018_eng.pdf

Influenza B continues to produce the vast majority of infections, with influenza A (H1N1 & H3N2) making up a minority of cases. Some excerpts from today's Hong Kong Flu Express (week 7) follow:

FLU EXPRESS
Flu Express is a weekly report produced by the Respiratory Disease Office of the Centre for Health Protection. It monitors and summarizes the latest local and global influenza activities.

Local Situation of Influenza Activity (as of Feb 21, 2018)

Reporting period: Feb 11 – 17, 2018 (Week 7)

  • The latest surveillance data showed that the local influenza activity remained at a high level in the past few weeks. Currently the predominating virus is influenza B.
  • Influenza can cause serious illnesses in high-risk individuals and even healthy persons. Given that seasonal influenza vaccines are safe and effective, all persons aged 6 months or above except those with known contraindications are recommended to receive influenza vaccine to protect themselves against seasonal influenza and its complications, as well as related hospitalisations and deaths.
  • Apart from adopting personal, hand and environmental hygiene practices against respiratory illnesses, those members of the public who have not received influenza vaccine are urged to get vaccinated as soon as possible for personal protection.

(SNIP)


Influenza-like-illness surveillance among sentinel general outpatient clinics and sentinel private doctors, 2014-18


In week 7, the average consultation rate for influenza-like illness (ILI) among sentinel general outpatient clinics (GOPCs) was 7.3 ILI cases per 1,000 consultations, which was lower than 8.9 recorded in the previous week (Figure 1, left). The average consultation rate for ILI among sentinel private doctors was 36.4 ILI cases per 1,000 consultations, which was lower than 71.3 recorded in the previous week (Figure 1, right).
https://www.chp.gov.hk/files/pdf/fluexpress_week07_22_02_2018_eng.pdf

 (SNIP)
Since the start of the 2017/18 winter influenza season in week 2, 373 adult cases of ICU admission/death with laboratory confirmation of influenza were recorded, in which 228 of them were fatal (as of February 21). Among them, 317 patients had infection with influenza B, 29patients with influenza A(H1N1)pdm09, 17 patients with influenza A(H3N2), three patients with influenza C and seven patients with influenza A pending subtype.

  • In comparison, 283, 207 and 88 adult cases were recorded in the same duration of surveillance(six complete weeks) in the 2014/15 winter, 2015/16 winter and 2017 summer seasons respectively, as compared with 327 cases in the current season (Figure 10, left). The corresponding figures for deaths were 208, 89 and 67 in the above seasons, as compared with 195 deaths in the current season (Figure 10, right).

(SNIP)

Severe influenza cases of all ages


• Since the start of the current winter influenza season in week 2, 388 severe influenza cases among all ages have been reported, including 230 deaths (as of February 21).




 • Among the adult fatal cases, about 83% had chronic diseases. Both of the two paediatric fatal cases did not have chronic diseases.
• Among patients with laboratory confirmation of influenza admitted to public hospitals in this season (from January 7 to February 21), 2.0% of admitted cases died during the same episode of admission. So far, it was within the historical range between 1.9% (2015/16 winter season) and 3.3% (2015 summer season).


 (SNIP)

Global Situation of Influenza Activity
  • In Mainland China (week ending Feb 11, 2018), both southern and northern provinces were still in winter influenza season but the activity continued to decrease. The proportion of influenza A detection was higher than that of influenza B. Influenza A(H1N1) and influenza B Yamagata viruses are predominating while levels of influenza A(H3N2) and influenza B Victoria viruses remained low. In southern provinces, the proportion of ILI cases in emergency and outpatient departments reported by sentinel hospitals was 4.7%, lower than that reported in the previous week (5.1%) but higher than that in the corresponding period in 2015-2017 (2.8%, 4.6%, 2.6%). In northern provinces, that proportion was 3.7%, lower than those reported in the previous week (4.2%) and the corresponding period in 2016 (5.1%), but higher than those in the corresponding period in 2015 and 2017 (both were 2.9%). The proportion of influenza detections in the week ending Feb 11, 2018 was 36.4% (65.2% influenza A and 34.8% influenza B).
  • In Macau (as of Feb 21, 2018), the influenza activity has been slowed down but remained at high level. The proportions of ILI cases in emergency departments among adults and children decreased.
  •  In Taiwan (week ending Feb 17, 2018), influenza activity was similar to the previous week and remained at the peak of the season. In the week ending Feb 17, the proportion of ILI cases in emergency department was 17.61% which was above the threshold of 11.4%. The predominating virus was influenza B.
  •  In Japan (week ending Feb 11, 2018), the influenza season has started in late November 2017. The average number of reported ILI cases per sentinel site has decreased to 45.38 in the week ending Feb 11, 2018 from 54.33 in the previous week. It was higher than the baseline level of 1.00. The predominating virus in the past five weeks was influenza B, followed by influenza A(H3N2) and A(H1N1)pdm09.

WHO: Genetic Characteristics Of Avian H7N4

Credit CDC











 







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Eight days ago, in Jiangsu China Reports 1st Novel H7N4 Human Infection, China announced the first known human infection with avian H7N4 which resulted in a 3-week hospitalization for a 68 year old woman in Jiangsu Province for severe pneumonia.

While human infection with avian H7 viruses hasn't been unheard of, until H7N9 emerged in China in 2013, they were fairly rare and almost always mild.  A few examples include:
After the wake up call from H7N9, when a severe human infection with a novel H7N4 virus is reported from China, we naturally take notice.

Today, in addition to releasing their Recommended Composition Of 2018-2019 Northern Hemisphere Flu Vaccine, the World Health Organization has released a new Antigenic and genetic characteristics of zoonotic influenza viruses report for February 2018.

Included is the following excerpt on the recently reported H7N4 virus, which shows that this virus is a purely avian LPAI H7 strain - distinct from A(H7N9) - although it carries the PB2  637K marker associated with mammalian adaptation.
Researchers have determined the (E627K) substitution in the (PB2) protein - the swapping out of the amino acid Glutamic acid (E) at position 627 for Lysine (K) - makes the an influenza virus better able to replicate at the lower temperatures (roughly 33C) normally found in the upper human respiratory tract (see Eurosurveillance: Genetic Analysis Of Novel H7N9 Virus).
Although the virus was not isolated (only detected by RT-PCR) in the patient, it was isolated from contact poultry.  A brief excerpt (bolding mine) from today's report:

Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines

(EXCERPT)

Influenza A(H7N4)

Influenza A(H7N4) activity from 26 September 2017 to 19 February 2018
The first human case of influenza A(H7N4) virus infection was reported by China. The case was from Jiangsu province, and the individual developed severe pneumonia and survived. The throat swab collected from the patient tested positive for A(H7N4) by real-time RT-PCR and sequencing. The individual had slaughtered chickens prior to illness onset and LPAI A(H7N4) viruses were detected in ducks and chickens on the premises. None of the close contacts of the infected individual reported symptoms and all tested negative for influenza.

Genetic characteristics of the influenza A(H7N4) virus

 
Viral gene sequence analysis generated from clinical material showed that all segments of the human virus shared high identity with wild bird avian influenza viruses. The HA gene was distinct from the A(H7N9) viruses circulating in China and was characterised as low pathogenicity by HA cleavage site sequence. No mutations associated with reduced susceptibility to neuraminidase inhibitors, amantadine or rimantadine, were found. The PB2 carried the 627K marker associated with mammalian adaptation. Virus has not been isolated from the infected individual.


Influenza A(H7) candidate vaccine viruses

 
Based on the current antigenic, genetic and epidemiologic data, no new CVVs are proposed. The available A(H7) CVVs, excluding A(H7N9) CVVs listed above, are listed in Table 6.
       
http://www.who.int/influenza/vaccines/virus/201802_zoonotic_vaccinevirusupdate.pdf?ua=1



Whether this is a one-off event, or the first hint of a new emerging threat, is impossible to say.  But the fact that this isn't a reassortment of the already endemic, and highly dangerous H7N9 virus is probably a good sign.