Monday, April 24, 2017

WHO MERS Update - A Household Cluster In The UAE














#12,406

On April 11th the UAE's Health Authority announced the detection of a single MERS case in Abu Dhabi, albeit with almost zero details provided.

Overnight, the Arabic media has carried reports (which I've been unable to verify off the HAAD website), saying the UAE's health authority has recently issued new, stronger guidelines for testing of respiratory samples.


Abu Dhabi Health" issued an updated standard for monitoring influenza


Date: April 24 2017   

The Health Authority in Abu Dhabi has issued a standard up to date to control and monitor the active influenza and diseases like influenza cases, and called on all health facilities and laboratories in the Emirate of Abu Dhabi to the need to follow the ways of dealing with similar symptoms of influenza cases and infection control in accordance with the instructions and standards body and prompt reporting electronically for any case applicable case definition sick infected with influenza, as well as laboratory results.

The Commission stressed that all health care facilities on the epidemiological investigation of the virus Middle respiratory center «Corona» syndrome and demanded to take all precautions with any confirmed or suspected to be infected with the virus case, and compliance with the directives guiding the World Health Organization regarding the verification and examination and taking into account the procedures for the prevention of infection and control of epidemic diseases acute respiratory symptoms, stressing the need to follow the due precautions in cases dealing with any patient suffering from symptoms similar to the flu.
         (Continue . . . )


While I was waiting for some official confirmation or further details on this story, the World Health Organization published details on the April 11th case, which we now learn involved two cases. The index patient, a 31 y.o. male who died, and a `household contact' who tested positive, but remained asymptomatic.
Asymptomatic MERS cases, once thought to be fairly rare, are turning up more often as more rigorous testing of contacts of known cases (see last summer's Saudi MOH On KKUH MERS Outbreak & Increased Asymptomatic Detections) has become policy in the Middle East. 

While suspected, the role of asymptomatic or mildly symptomatic cases in spreading the virus in the community remains unproven.   

Middle East respiratory syndrome coronavirus (MERS-CoV) – United Arab Emirates
Disease outbreak news
24 April 2017

Between 9 and 11 April 2017, the National IHR Focal Point of United Arab Emirates (UAE) reported two additional cases of Middle East Respiratory Syndrome Coronavirus (MERS-CoV). 

Details of the cases

The two cases identified in Abu Dhabi, UAE, were roommates. The case reported to WHO on 9 April 2017 (31-year-old) passed away on 16 April 2017 and the second case reported to WHO on 11 April 2017, identified through tracing of household contacts, is asymptomatic and has been admitted to a negative pressure isolation room on a ward in hospital. The source of infection of the 31-year-old MERS case is under investigation. Contact tracing of household and healthcare contacts is ongoing. Detailed information concerning the cases can be found in a separate document (see link below).
  MERS-CoV cases reported between 9 April and 11 April 2017
xlsx, 22kb


To date, United Arab Emirates has reported 81 laboratory confirmed cases of MERS. The last case was reported in June 2016 (see Disease Outbreak News published on 21 June 2016).

Globally, since September 2012, 1938 laboratory-confirmed cases of infection with MERS-CoV including at least 691 related deaths have been reported to WHO.

WHO risk assessment

MERS-CoV causes severe human infections resulting in high mortality and has demonstrated the ability to transmit between humans. So far, the observed human-to-human transmission has occurred mainly in health care settings.

The notification of additional cases does not change the overall risk assessment. WHO expects that additional cases of MERS-CoV infection will be reported from the Middle East, and that cases will continue to be exported to other countries by individuals who might acquire the infection after exposure to animals or animal products (for example, following contact with dromedaries) or human source (for example, in a health care setting). WHO continues to monitor the epidemiological situation and conducts risk assessment based on the latest available information.

Although reported MERS activity has been fairly low across the Middle East this year, we've seen estimates that a lot more cases probably occur than are diagnosed.  This call by the UAE's Health Ministry for more rigorous testing of suspected MERS cases could go a long way towards firming up those estimates.



Jilin Province Reports 1st H7N9 Case Of 2017

Modified FAO Map (Jilin Circle & 38th Parallel Added)














#12,405


As discussed last week in Beijing CDC - Three More Locally Acquired H7N9 Cases - and as depicted in the map above - H7N9 has been, if not exclusively, at least primarily a problem for Southern and Central China. 
The vast majority of cases have been reported south of the 38th parallel. 
Over the past month we've seen a surge in cases in and around Beijing, a region that has been largely spared from H7N9's impact.  This has raised concerns in the Capital, and has sparked numerous local drills, and inspections of local markets.

Further north and east, and with borders to both North Korea and Russia, lies Jilin Province. During the first four epidemic waves, only 2 cases have ever been reported from Jilin - both during the second wave in the spring of 2014 (see H7N9 Moves North, Guangdong Reports New Cases).


Over the weekend Jilin's Health Ministry reported their first case of this 5th wave, that of a 34 year old man from Tonghua, a city with more than 2 million residents located not far from the North Korean border.

Province this year found the first case of human infection with H7N9 influenza cases confirmed

Published: 2017-04-22     Source: Office of Emergency      

  April 22, Jilin Provincial Health Family Planning Commission informed by Jilin CDC H7N9 virus nucleic acid detection for review, Tonghua City, found a case of human infection with confirmed H7N9 influenza cases, this is the first case of human infection this year, Jilin Province confirmed cases of H7N9 influenza. Patients were male, 34 years old, currently designated hospital for isolation and treatment in a critical condition.

  Experts remind the general public, people infected with H7N9 influenza preventable, controllable and curable, the public should be treated rationally, do not panic. Daily life, the need to cultivate a healthy diet and lifestyle, physical activity, the occurrence of fever and respiratory symptoms, should go to regular medical institutions.

While human cases remain extremely sparse in the northern provinces, and we've seen no indication of sustained or efficient human-to-human transmission of this virus anywhere in China, this latest case has not escaped the notice of the Russian press, which carried the following headline overnight:

Bird flu reached the border with the Russian Federation of Chinese Jilin Province
The first case of H7N9 virus in 2017 was registered in Jilin Province

As we discussed last month in China's Nervous Neighbors, this year's unprecedented H7N9 outbreak has Russia, Vietnam, and much of South Central Asia on alert, as fears grow that this virus will eventually make its way out of China and begin to spread in adjacent countries.

At a time of year when H7N9 cases would normally be winding down, this week saw a doubling of cases over recent week's tallies (see HK CHP Notified Of 27 New H7N9 Cases From The Mainland), with nearly a third of those from north of the 39th parallel.
Whether this spike in cases is a trend, or merely a temporary blip in the data, will require several more weeks to determine. But it is worth noting that over the weekend - in addition to the Jilin case - we've seen fresh reports of H7N9 cases from Hubei, Hunan, and Sichuan provinces.

Sunday, April 23, 2017

Community Pandemic Mitigation's Primary Goal : Flattening The Curve














#12,404


When the next influenza pandemic virus emerges and begins to spread around the world, the CDC, HHS, WHO and other partners will work to contain the outbreak at its source (if possible), to slow its spread internationally (again, if possible), and begin to work on a vaccine.
A vaccine - while viewed as the best response to a pandemic, will take time. How much time, will depend on a lot of factors.
Despite improved vaccine manufacturing technologies, we would have to get very lucky to have any significant quantity of vaccine available for the general public in less than six months.

A novel virus may require 2 shots - a month apart - to invoke an adequate immune response, and that assumes an effective vaccine can be made at all.
Add in the inevitable global scramble for a limited supply of any vaccine, the logistics of deploying said vaccine to billions of people in a short period of time . . .   and well - the TV and movie cliche where some valiant scientist creates, tests, and distributes a vaccine in the nick of time is a pretty optimistic scenario.

This isn't to dismiss the importance of a vaccine.  Pandemics tend to come in waves.  The 1918 pandemic - which killed between 50 and 100 million people - came in three distinct waves, over an 18 month period. 
Even if a vaccine isn't available for the first wave, it could save millions of lives in the waves that follow.
But until a vaccine is widely available, the goal is to slow the spread of a pandemic virus, to limit its impact, and to try to save as many lives as possible through the use of NPIs - Nonpharmaceutical Interventions.
 
The CDC’s Nonpharmaceutical Interventions (NPIs) webpage defines NPIs as:
Nonpharmaceutical interventions (NPIs) are actions, apart from getting vaccinated and taking medicine, that people and communities can take to help slow the spread of illnesses like influenza (flu). NPIs are also known as community mitigation strategies.

While some may scoff at their effectiveness, we have a real-world example during the worst flu pandemic in recorded history  - the 1918 Spanish flu.



The chart above, taken from the PNAS journal article entitled Public Health Interventions and Pandemic Intensity During the 1918 Influenza Pandemic, illustrates what happened in two American cities during the 1918 pandemic. 
  • The sharp, but much shorter pandemic wave depicted by the solid line occurred in Philadelphia, where relatively few steps were taken by the public health department to slow the spread of the disease (they even ok'd a massive Liberty Loan parade on September 28th).   
  • The dotted line represents St. Louis, which closed schools early and where the Health Department prohibited public gatherings in places like theaters, churches, and restaurants. 
As you can see, the percentage of cases reported on a daily basis were far fewer in St. Louis, but their pandemic wave lasted nearly twice as long as in Philadelphia. 
 
At its worst, the percentage of excess of people afflicted in the city of Philadelphia was 5 times greater than what St. Louis experienced. The burden on hospitals, mortuaries, and practically all segments of the economy was certainly far greater.  
None of this is a new concept, and we were discussing these issues 10 years ago when the previous Community Mitigation Guidelines were released.

This is why the primary goal of the HHS/CDC's 2017 revised Community Mitigation Guidelines to Prevent Pandemic Influenza - which we've already looked at twice yesterday (see here, and here)is to slow the spread of any pandemic outbreak, in hopes of limiting its impact on hospitals, essential workers, infrastructure, and ultimately reducing the death toll. 

An excerpt from the summary reads:

Purpose

The purpose of these guidelines is to help state, tribal, local, and territorial health departments with prepandemic planning and decision-making by providing updated recommendations on the use of NPIs. 

These recommendations have incorporated lessons learned from the federal, state, and local responses to the influenza A (H1N1)pdm09 virus pandemic (hereafter referred to as the 2009 H1N1 pandemic) and findings from research. Communities, families and individuals, employers, and schools can create plans that use these interventions to help slow the spread of a pandemic and prevent disease and death.

Specific goals for implementing NPIs early in a pandemic include slowing acceleration of the number of cases in a community, reducing the peak number of cases during the pandemic and related health care demands on hospitals and infrastructure, and decreasing overall cases and health effects ( Figure 1).
When a pandemic begins, public health authorities need to decide on an appropriate set of NPIs for implementation and to reiterate the importance of personal protective measures for everyday use (e.g., voluntary home isolation of ill persons [staying home when ill], respiratory etiquette, and hand hygiene) and environmental cleaning measures (e.g., routine cleaning of frequently touched surfaces), which are recommended at all times for prevention of respiratory illnesses ( Table 1).

Personal protective measures reserved for pandemics (e.g., voluntary home quarantine of exposed household members [staying home when a household member is ill] and use of face masks by ill persons) also might be recommended (Table 1). A more difficult decision is how and when to implement community-level NPIs that might be warranted but are more disruptive (e.g., temporary school closures and dismissals, social distancing in workplaces and the community, and cancellation of mass gatherings) (Table 1).

These decisions are made by state and local officials on the basis of conditions in the applicable jurisdictions, with guidance from CDC (according to pandemic severity and potential efficacy) and governing authorities (1). Prepandemic planning, along with community engagement, is an essential component of these decisions ( Table 2).
         (Continue . . . .)



Although there may be other pharmaceutical options - like antivirals - available at the start of a pandemic, those will be in finite supply and are not a panacea for infection.  Prevention is always better than treatment, but never more so than during a pandemic, when treatment options may quickly become limited.

Hospital beds, ventilators, even hospital staff - may all be in short supply during a pandemic (nurses get sick, too) - which makes it all the more imperative we flatten the curve - even if it means extending the duration of a pandemic wave.

While telling people to wash their hands, cover their coughs, avoid crowds, and stay home while sick may seem like a weak response to a pandemic - in truth, they (and other more disruptive measures like school closures, cancellation of public events, etc.) may be our most powerful weapons in any pandemic.
But they must be properly applied, else they could do more harm than good.
It's neither practical or desirable to simply shut everything down at the first sneeze, and try to wait out what could be a year (or longer) pandemic. Very few are equipped to do so, and besides, someone has to keep the lights on, deliver the food, refine the fuel, police the streets,  take care of the sick and injured . . . and do the thousands of other things that hold civilization together.
We'll have to find ways to live and work as safely as possible during a pandemic. Else the virus could quickly become the least of our problems.

Which is the point of these new guidelines. A severe pandemic will require some difficult, and likely unpopular, decisions on the part of public health and government officials. If those decisions were easy, or clear cut, I suspect it wouldn't take near 160 pages to help explain the scientific rationale behind them.  
It's not an exact science, and no one should expect that all will go smoothly during a pandemic, even with these new guidelines.
But at least we have the experience of the 2009 pandemic under our belts, along with 10 years of additional science, to augment and improve the previous set of guidelines. For a look as some of the research on NPIs over the past few years, you may wish to revisit:

Study: Effectiveness of NPIs Against ILI's

Michigan NPI Study: A Closer Look


Study: Efficacy Of Hand Hygiene Alone Against Influenza Infection
NPI’s and Influenza

Study: NPI's Can Help Prevent Spread Of Flu-Like Illnesses



Saturday, April 22, 2017

PSAF Is The New Pandemic Severity Index




















#12,403

In this, our first close look at the revised 2017 CDC/HHS Community Pandemic Mitigation Plan, published yesterday in the MMWR, we look at the new gauge of pandemic intensity; the PSAF (Pandemic Severity Assessment Framework). 

The Pandemic Severity Index (see graphic below) was adopted in the 2007 Community Strategy for Pandemic Influenza Mitigation plan as a way to quantify the likely impact of any pandemic outbreak.  It was based on the initial CFR (Case Fatality Ratio) of the virus, and was modeled in many respects after the 5 category Saffir-Simpson wind scale used for hurricanes. 


While a familiar format to most Americans, it ran into some of the same problems during the 2009 pandemic that the Saffir-Simpson scale has run into with Hurricane Katrina in New Orleans, Superstorm Sandy in New York, and Hurricane Mathew along Florida's east coast.

A single metric (be it CFR or wind speed) doesn't always accurately predict the impact of a pandemic or a hurricane.

In 2009, early reports (where the most seriously ill are most likely to be identified) suggested an elevated case fatality rate. Not unexpectedly, people were taking that number, and multiplying it times 30% of the population, and coming up with horrendous death tolls (see Categorically Speaking).
And just as there can be a huge difference in damage between a Cat 3 hurricane hitting Miami (as Wilma did in 2005), and a Cat 3 hitting New Orleans (as Katrina did the same year), what may turn out to be a CAT 1 pandemic in Ottumwa, Iowa could well end up being a CAT 2+ pandemic in Mumbai, India.
A one size-fits-all rating, based on a single (easily misjudged) metric, can go quickly awry.  Add in the fact that pandemic viruses are constantly evolving, and what might start out as a mild pandemic could strengthen over time, while a severe pandemic might weaken greatly after the opening weeks or months.

What is needed is a more comprehensive and encompassing method of assessing a pandemic virus and predicting its likely impact. To that end, we have the PSAF.  

Pandemic Severity Assessment Framework (PSAF)
 
Assessing Pandemic Severity and Health Impact


When a novel influenza virus emerges that can spread easily and efficiently and cause a pandemic, CDC and partners must gauge its projected impact and recommend rapid action to reduce virus transmission, protect vulnerable population groups, and minimize societal disruption (5). Historically, the severity of influenza pandemics has been estimated by calculating case-fatality ratios.§§ However, as we learned during the 2009 H1N1 pandemic (Box 1), case-fatality ratios may be difficult to measure early in a pandemic because of care-seeking behavior and testing practices (i.e., not everyone will seek care for their illness, and not everyone will be tested and diagnosed with pandemic influenza). As a result, severe and fatal cases may be more likely to be reported, creating a bias.


Due to such limitations, reliance on any single measure of viral transmission or clinical outcomes is unlikely to provide an accurate estimate of the potential impact of an emerging pandemic. CDC has, therefore, developed a new assessment framework that uses multiple clinical and epidemiologic indicators to create a comprehensive picture of the potential impact of an emerging pandemic (3). As indicated in Tables 5 and 6, the Pandemic Severity Assessment Framework (PSAF) estimates pandemic severity (or health impact) by synthesizing multiple measurements of:

  •  Viral transmissibility, including school, workplace, and/or community attack rates, secondary household attack rates, school and/or workplace absenteeism rates, and rates of emergency department and outpatient visits for ILI.
  •  Clinical severity, including case-fatality ratios, case-hospitalization ratios, and deaths-hospitalizations ratios.
Additional PSAF data may be obtained by characterizing genetic markers in a pandemic virus and by conducting animal studies on its transmissibility and virulence.





No matter how well designed the algorithm, getting good numbers out of a formula requires plugging `good' numbers in. And getting those numbers - particularly through the `fog of flu' common in the early days of a pandemic - may not be possible.

But once reasonably accurate data becomes available, this method ought to provide us with a much better idea of what we are facing and must prepare for.

CDC/HHS Community Pandemic Mitigation Plan - 2017














#12,402


Just over 10 years (Feb. 1st, 2007), at a time when H5N1 was the hot pandemic topic, the CDC & HHS unveiled their 2007 Community Strategy for Pandemic Influenza Mitigation plan. This 108 page document covered a variety of topics, including the creation of a pandemic severity scale, and the expected role of NPI's (Non Pharmaceutical Interventions) in combating any pandemic outbreak (see The CDC Does NPI).
Two years later, the 2009 H1N1 pandemic erupted, and while not the virus (or the severity) originally feared, these guidelines provided an important set of tools for the incoming administration to use - particularly in the early days and weeks  of the outbreak. 
Fast forward a full decade, and with the experiences of a moderate pandemic under our belts, and a far more complex line up of novel flu viruses (H5N1, H5N8, H7N9, H5N6, H3N2v, H1N2v, H1N1v, etc) in play, the CDC/HHS has decided to revise and hone the previous document, and replace it with a 2017 Community Mitigation Guidelines to Prevent Pandemic Influenza.

The overview was published yesterday in the MMWR, and while lengthy, is but a fraction of the entire document.  When you add in the two supplemental documents, this new set of guidelines runs over 160 pages, starting with:

Community Mitigation Guidelines to Prevent Pandemic Influenza — United States, 2017 
Recommendations and Reports / April 21, 2017 / 66(1);1–34
Noreen Qualls, DrPH1; Alexandra Levitt, PhD2; Neha Kanade, MPH1,3; Narue Wright-Jegede, MPH1,4; Stephanie Dopson, ScD5; Matthew Biggerstaff, MPH6; Carrie Reed, DSc6; Amra Uzicanin, MD1 (View author affiliations)

This HTML version contains only about half of the full PDF file (https://www.cdc.gov/mmwr/volumes/66/rr/pdfs/rr6601.pdf).

The two supplemental documents are:

Published Date: April 21, 2017 
Source: Qualls N, Levitt A, Kanade N, et al. Community Mitigation Guidelines to Prevent Pandemic Influenza — United States, 2017. MMWR Recomm Rep 2017;66(No. RR-1):1–34.

         Published Date: April 21, 2017 
Source: Qualls N, Levitt A, Kanade N, et al. Community Mitigation Guidelines to Prevent Pandemic Influenza — United States, 2017. MMWR Recomm Rep 2017;66(No. RR-1):1–34.
If it sounds as if there is a lot to read and absorb here, you're right.   I've only just begun to dig into the details. Over the next week or two I hope to flesh out some of the highlights, and compare this new document to the old one.

A couple of months ago, in Probably Not The Worst Idea In The World . . ., we discussed how now might be a good time for businesses and agencies to take out their old pandemic plans, dust them off, and revise them as needed. 

Perhaps this latest release from the MMWR will help to inspire other entities - both public and private - to follow suit.



WHO Avian Flu Risk Assessment - April 2017

















#12,401



The World Health Organization has released an updated Influenza at the human-animal interface report - one that reflects H7N9 cases officially notified to WHO by the Chinese government through April 20th of this year, along with a single H9N2 infection reported in a child from Gansu Province, China. 
This report is dated April 20th, but since China doesn't always notify WHO immediately of cases, today's report is running roughly 30 behind Hong Kong's most recent tally. 
Two HPAI H5 viruses with a track record of infecting humans (H5N1 & H5N6) were not diagnosed during this latest reporting period, with only 2 H5N1 cases reported thus far in 2017, and the last human H5N6 infection reported last November in China.


First some excerpts from today's report, then I'll return with a bit more.

Influenza at the human-animal interface

Summary and assessment, 16 March to 20 April 2017

  • New infections1: Since the previous update, new human infections with influenza A(H7N9) and A(H9N2) viruses were reported.
  • Risk assessment: The overall public health risk from currently known influenza viruses at the human-animal interface has not changed, and the likelihood of sustained human-to-human transmission of these viruses remains low. Further human infections with viruses of animal origin are expected.
  • IHR compliance: All human infections caused by a new influenza subtype are required to be reported under the International Health Regulations (IHR, 2005).2 This includes any animal and non-circulating seasonal influenza viruses. Information from these notifications is critical to inform risk assessments for influenza at the human-animal interface.

Avian Influenza Viruses

 
Avian influenza A(H5) viruses

 
Current situation:
Since the last update, no new laboratory-confirmed human cases of influenza A(H5) virus infection were reported to WHO. Influenza A(H5) subtype viruses have the potential to cause disease in humans and thus far, no human cases, other than those with influenza A(H5N1) and A(H5N6) viruses, have been reported to WHO. According to reports received by the World Organisation for Animal Health (OIE), various influenza A(H5) subtypes continue to be detected in birds in Africa, Europe and Asia.


Avian influenza A(H7N9) viruses


Current situation: During this reporting period, 86 laboratory-confirmed human cases of influenza A(H7N9) virus infection were reported to WHO from China. Case details are presented in the table in the Annex of this document. For additional details on these cases, public health interventions, and the recently detected highly pathogenic avian influenza (HPAI) A(H7N9) viruses, see the Disease Outbreak News.


As of 20 April 2017, a total of 1393 laboratory-confirmed cases of human infection with avian influenza A(H7N9) viruses, including at least 534 deaths3, have been reported to WHO (Figure 1).


1 For epidemiological and virological features of human infections with animal influenza viruses not reported in this assessment, see the yearly report on human cases of influenza at the human-animal interface published in the Weekly Epidemiological Record. www.who.int/wer/en/
2 World Health Organization. Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005). www.who.int/ihr/Case_Definitions.pdf

3 Total number of fatal cases is published on a monthly basis by China National Health and Family Planning Commission.

According to reports received by the Food and Agriculture Organization (FAO) on surveillance activities for avian influenza A(H7N9) viruses in China4, positives among virological samples continue to be detected mainly from live bird markets, and some commercial and backyard farms.

Risk Assessment

1. What is the likelihood that additional human cases of infection with avian influenza A(H7N9) viruses will occur? Most human cases are exposed to the A(H7N9) virus through contact with infected poultry or contaminated environments, including live poultry markets. Since the virus continues to be detected in animals and environments, further human cases can be expected. Additional sporadic human cases of influenza A(H7N9) in other provinces in China that have not yet reported human cases are also expected.
2. What is the likelihood of human-to-human transmission of avian influenza A(H7N9) viruses? Even though small clusters of cases have been reported, including those involving healthcare workers, currently available epidemiological and virological evidence suggests that this virus has not acquired the ability of sustained transmission among humans, thus the likelihood is low.

 
3. What is the risk of international spread of avian influenza A(H7N9) virus by travellers? Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival. If this were to occur, further community level spread is considered unlikely as this virus has not acquired the ability to transmit easily among humans.
4 Food and Agriculture Organization. H7N9 situation update. www.fao.org/ag/againfo/programmes/en/empres/H7N9/situation_update.html

Avian influenza A(H9N2) viruses
Current situation:

 
One new laboratory-confirmed human case of A(H9N2) virus infection was reported to WHO from China in an eleven-month-old boy from Gansu province. The case developed mild illness on 6 February 2017, was hospitalized and has recovered. He had exposure to backyard poultry prior to illness onset. This is the first human case of avian influenza A(H9N2) virus infection reported to WHO since December 2016 and the first human case reported from Gansu province. Avian influenza A(H9N2) viruses are enzootic in poultry in China.

Risk Assessment:
1. What is the likelihood that additional human cases of infection with avian influenza A(H9N2) viruses will occur? Most human cases are exposed to the A(H9N2) virus through contact with infected poultry or contaminated environments. Human infection tends to result in mild clinical illness. Since the virus continues to be detected in poultry populations, further human cases can be expected.
2. What is the likelihood of human-to-human transmission of avian influenza A(H9N2) viruses? No case clusters have been reported. Currently available epidemiological and virological evidence suggests that this virus has not acquired the ability of sustained transmission among humans, thus the likelihood is low.
3. What is the risk of international spread of avian influenza A(H9N2) virus by travellers? Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival. If this were to occur, further community level spread is considered unlikely as this virus has not acquired the ability to transmit easily among humans.
(Continue . . . )


While the risk assessments for H7N9 remains unchanged - and the virus has not demonstrated the ability to transmit efficiently from human to human -  it is fair to say that  recent developments with this virus have raised concerns world wide.

  1. This year's surge in human cases not only ends a two year decline in the number of  human infections, it is well on its way to more than doubling the size of its biggest previous epidemic (320 cases in the winter 2013-14).  
  2. H7N9 has recently split into two major lineages - Pearl River Delta and Yangtze River Delta - (see MMWR:Increase in Human Infections with Avian Influenza A(H7N9) In China's 5th Wave) This new (Yangtze River Delta) lineage will require a new vaccine - meanwhile the virus continues to evolve at an impressive rate.
  3. Previously only an LPAI virus, a new virulent (in birds) HPAI version of H7N9 emerged in Guangdong province this winter, and has demonstrated the ability to infect humans. 
  4. In a recent Eurosurveillance Research Article it was reported that despite better medical treatment for patients, the mortality rate remains high (30%+), and the authors report an`accelerated disease progression of H7N9 patients', which they note  `suggests that the viral pathogenicity might have become stronger'.
  5. The authors also noted  ` . . .  increased detection rate of H7N9 in environmental samples suggests that the virus might become more resistant to high ambient temperature.' - which you may recall was a concern raised last summer (see HK CHP: Additional Details On China's July H7N9 Cases) when we saw a dozen `out of season H7N9 cases'. 


While none of this guarantees that H7N9 will spark the next pandemic, the CDC's IRAT ( Influenza Risk Assessment Tool) ranks H7N9 as having the highest pandemic potential of 11 novel viruses currently being tracked.
And earlier this month renown virologist Dr. Guan Yi at the University of Hong Kong, in a recent interview (see NPR: A Pessimistic Guan Yi On H7N9's Evolution),  was quoted as saying  "I think this virus poses the greatest threat to humanity than any other in the past 100 years."
Add in the recent expansion of H7N9 to the north (Beijing) and west (Tibet) of China, and you have ample reasons to put H7N9 at the very top of our influenza pandemic threats list.