WHO Novel Flu Summary & Risk Assessment - March 2023

#17,350

Overnight the World Health Organization published their latest novel flu summary, which covers the period from late January to early March.  Officially 6 new cases were reported (3 H5N1, 1 H5N6, 2 H9N2) under the IHR regulations, while another 4 (2 H9N2, and 2 H1N1v) from China were apparently relayed by `unofficial' channels. 

A recurring theme in these reports are reminders to all member nations of their obligation to report, in a timely fashion, all human infections with novel flu viruses (I've highlighted some of those passages below in red). 

As we've seen all too frequently over the years, that doesn't always happen.  Reports are often delayed by weeks or even months . . .  assuming we get them at all.   

Six of the 10 new cases mentioned in today's report were already publicly reported (see here, here, here, and here), while details on the other 4 remain murky. This update also confirms that both the Ecuadorian H5 case in January and Vietnam's case from last November were both H5N1, although the clade of Vietnam's case has not been determined. 

Some excerpts from this latest report follow. I'll have a brief postscript after the break. 

Influenza at the human-animal interface 

Summary and risk assessment, from 27 January to 3 March 20230

 • New infections  : From 27 January to 3 March 2023, three human cases of infection with influenza A(H5N1) viruses, one human case of infection with an influenza A(H5N6) virus and two human cases of infection with influenza A(H9N2) viruses were reported officially. Additionally, two human cases of infection with influenza A(H9N2) viruses and two human cases of infection with influenza A(H1N1) variant viruses were detected.

• 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. Human infections with viruses of animal origin are expected at the human-animal interface wherever these viruses circulate in animals. 

• Risk management: Selection of new candidate vaccine viruses (CVVs) for zoonotic influenza viruses for pandemic preparedness purposes was done during a recent WHO consultation.3 

• IHR compliance: All human infections caused by a new influenza subtype are required to be reported under the International Health Regulations (IHR, 2005).2F 4 This includes any influenza A virus that has demonstrated the capacity to infect a human and its haemagglutinin gene (or protein) is not a mutated form of those, i.e. A(H1) or A(H3), circulating widely in the human population. Information from these notifications is critical to inform risk assessments for influenza at the human-animal interface.

Current situation: 

Avian influenza A(H5) viruses 

Since the last risk assessment on 26 January 2023, three human cases of infection with influenza A(H5N1) viruses were reported to WHO. 

On 23 February 2023, Cambodia notified WHO of a confirmed case of human infection with avian influenza A(H5N1) virus. An 11-year-old girl from Prey Veng province developed symptoms on 14 February 2023 and received treatment at a local hospital. On 21 February, she was admitted to the National Pediatric Hospital with severe pneumonia. A sample was collected the same day through the severe acute respiratory infection (SARI) sentinel surveillance system. The sample tested positive for an avian influenza A(H5N1) virus by reverse transcriptase-polymerase chain reaction (RT-PCR) at the National Institute of Public Health on the same day. The sample was also sent to Institute Pasteur Cambodia, the National Influenza Center, which confirmed the finding. The patient died on 22 February.

Twelve close contacts (eight asymptomatic close contacts and four symptomatic who met the suspected case definition) of the child were identified and samples were collected and tested. One of the contacts was the child’s father, who also developed a mild influenza-like illness on 14 February and tested positive for influenza A(H5N1) on 23 February. The eleven other samples tested negative for A(H5N1) and SARS-CoV-2. 

Genetic sequence data of the viruses from both cases was shared through the publicly accessible database GISAID. Virus sequencing showed that the A(H5N1) viruses from the cases belong to the A(H5) genetic clade 2.3.2.1c and are similar to the 2.3.2.1c clade viruses circulating in poultry in southeast Asia since 2014. Field investigations revealed that both cases had exposure to sick and dead poultry. To date, there is no indication of human-to-human transmission of influenza A(H5N1) virus in this setting. In addition, active case finding has not identified any additional influenza A(H5N1) virus infections.5 

On 24 February 2023, China reported a case in a 53-year-old woman from Jiangsu province who developed symptoms on 31 January 2023. She was hospitalized on 4 February with severe pneumonia. She had exposure to backyard poultry in Anhui province. No further cases were suspected among family members at the time of reporting. Virus sequencing showed that the A(H5N1) virus from the case belongs to the A(H5) genetic clade 2.3.4.4b. 

Since the last risk assessment on 26 January 2023, one human case of infection with an influenza A(H5N6) virus was reported to WHO. On 2 February 2023, China reported a case in a 49-year-old man from Guangdong province who developed symptoms on 17 December 2022. He was hospitalized on 21 December with severe pneumonia and has since recovered and been discharged. He had exposure to backyard poultry and no further cases were suspected among family members at the time of reporting. 

In the most recent risk assessment of 26 January 2023, a human case of infection with an avian influenza A(H5) virus reported by Ecuador was included. Further laboratory information confirms the N-type of the virus as N1. Thus, the case is considered as a human case of infection with an influenza A(H5N1) virus.6 

In the risk assessment of 11 November 2022, a human case of infection with an avian influenza A(H5) virus reported by Viet Nam was included. Further laboratory information confirms the N-type of the virus as N1. Thus, the case is considered as a human case of infection with an influenza A(H5N1) virus. The A(H5) genetic clade that this virus belongs to is not known. 7

Avian influenza A(H9N2) viruses 

Since the last risk assessment on 26 January 2023, two human cases of infection with influenza A(H9N2) viruses were reported from China (see Table 1 below). No epidemiological links or clusters of cases were reported associated with these cases. All cases have recovered. The cases were detected in influenza-like illness surveillance. 

Additionally, two human cases of infection with influenza A(H9N2) viruses were detected in China according to information received during the WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2023-2024 Northern Hemisphere Influenza Season held in February 2023.8

Avian influenza A(H9N2) viruses are enzootic in poultry in Asia and increasingly reported in poultry in Africa.

Swine Influenza Viruses 

Current situation: 

Influenza A(H1N1) variant viruses [A(H1N1)v] 

Swine Influenza Viruses 

Since the last risk assessment on 26 January 2023, two human cases of infection with influenza A(H1N1)v viruses were detected in China according to information received during the WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2023-2024 Northern Hemisphere Influenza Season held in February 2023.9

          (SNIP)

• All human infections caused by a new subtype of influenza virus are notifiable under the International Health Regulations (IHR, 2005).4F 10 State Parties to the IHR (2005) are required to immediately notify WHO of any laboratory-confirmed case of a recent human infection caused by an influenza A virus with the potential to cause a pandemic12. Evidence of illness is not required for this report.

 • It is critical that these influenza viruses from animals or from people are fully characterized in appropriate animal or human health influenza reference laboratories. Under WHO’s Pandemic Influenza Preparedness (PIP) Framework, Member States are expected to share influenza viruses  with pandemic potential on a regular and timely basis  13 with the Global Influenza Surveillance and Response System (GISRS), a WHO-coordinated network of public health laboratories. The viruses are used by the public health laboratories to assess the risk of pandemic influenza and to develop candidate vaccine viruses.

          (Continue. . . )          

While the IHR 2005 is described as a `legally binding' agreement, there is little recourse for the WHO and the international community when a nation decides - for political, economic, or prestige reasons - to withhold crucial information.  

Seven years ago, in Adding Accountability To The IHR, we looked at the Ebola Interim Assessment Panel's recommendations for strengthening the IHR. It is fair to say that whatever changes have been made, have not been sufficient.

Over the past 3 years the COVID pandemic seems to have become an excuse for many nations not to report on novel outbreaks. The WHO often describes this diplomatically, as in their recent DON on MERS-CoV.

The number of MERS-CoV cases reported to WHO has substantially declined since the beginning of the ongoing COVID-19 pandemic. This is likely the result of epidemiological surveillance activities for COVID-19 being prioritized, resulting in reduced testing and detection of MERS-CoV cases.

Regardless of the reasons, without vastly improved surveillance and prompt reporting of emerging threats, we remain incredibly vulnerable to being blindsided by the next pandemic virus. 

Again.