“There is a lot of interest in” theH5N1 avian flu. “I want to emphasize that we are not” currently “in a situation where the production of a vaccine is necessary against pandemic influenza” for humans, but if needed there is already “a pipeline” and a system ready to activate. This is assured by the epidemiologist Maria Van Kerkhove, who at the World Health Organization (WHO) leads the Preparation and Prevention against Epidemics and Pandemics (Epp). “If the situation – he explains in a focus posted via social media – were to evolve into a Pheic”, i.e. a public health emergency of international importance, “or a pandemic” as was the case with Covid-19, “but once again – specifies the expert – we are not at that point, with current vaccination technologies we estimate that 4-8 billion doses of pandemic influenza vaccines could be produced in a year (depending on how much antigen is needed in each vaccine).”
This estimate, Van Kerkhove explains, “does not include new vaccine platforms, such as mRNA and viral vectors, which have not yet obtained authorization for influenza vaccines. Since the WHO has an existing pipeline of CVVs (candidate vaccine viruses) and of flu vaccine production, the production process would be faster than that for Covid e we could start having vaccines available within 4-6 months. WHO has arrangements in place whereby we would have access to around 11-12% of the real-time production of vaccines to distribute them to Member States based on risk and need.”
How does it all work?
“WHO, through the Pandemic Influenza Preparedness (PIP) Framework established in 2011, has agreements for the rapid development of vaccines if we need them – he explains – Based on the current situation, it is not necessary to activate this system”, but through this is possible “access to vaccines to be used based on risk and need”. At the moment, Van Kerkhove explains, regarding the avian flu which is alerting experts in recent days, “there are 2 candidate CVV vaccine viruses related to the circulating viruses of the H5 2.3.4.4b clade available for vaccine development and, if the situation warranted it, for production”.
WHO’s work on influenza, continues Van Kerkhove, “spans over 7 decades with the Global Influenza Surveillance and Response System (Gisrs), a network now made up of 152 WHO national centers in 130 member states, 7 WHO collaboration centers and 12 WHO reference laboratories H5”. This system “functions as a global surveillance mechanism; preparedness and response to seasonal, pandemic and zoonotic influenza; global platform for monitoring influenza epidemic and disease; global alert system for new influenza viruses and other respiratory pathogens “. It is a network that must “evaluate circulating influenza viruses and select CVVs for the development” of shield products “against both seasonal and zoonotic influenza (for example avian flu)”.
The selection and development of zoonotic influenza CVVs are activities “aimed at pandemic preparation and the first steps towards the timely production of vaccines – Van Kerkhove clarifies again – This does not imply a recommendation to start production”. The expert therefore explains how the preparatory machine works. “National authorities may consider the use of one or more of these vaccine virus candidates for pilot batch vaccine production, clinical trials and other preparedness purposes based on risk assessments and public health needs.” .
For now low risk, up to moderate in exposed people
For avian influenza A/H5N1 the latest risk assessment developed by the World Health Organization (WHO), with the Woah (World Organization for Animal Health) and the FAO (United Nations Food and Agriculture Organization) agriculture), is dated 23 April. “The context is implicit: a human case of ‘avian flu’ associated with contact with an infected cow has been reported in the United States (where active surveillance is ongoing).” Based on the information available to date, “we assess the current overall public health risk posed by A/H5N1 as low and, for those exposed to infected birds or animals or contaminated environments, the risk of infection is considered low to moderate”, reiterates Van Kerkhove.
The expert, in a focus posted on X, explains that “Globally, as of 2021, 28 human cases of H5N1 have been reported and no human-to-human transmission has been detected among these cases (in most situations molecular and serological tests are active in the countries that have detected them)”. Today, he analyses, “we are certainly witnessing an expansion of the H5N1 virus in animals – poultry, wild birds, mammals – and to the infection of new species. At present, the virus is an animal virus that causes sporadic human infections.”
The advices
“Globally – underlines Van Kerkhove – we need stronger surveillance in animals and humans in contact with animals; rapid detection and active case finding especially in high-risk groups, including those with occupational exposure to infected animals; to rapidly share surveillance data and genetic sequencing for risk assessment. We need those who come into contact with animals to follow the latest guidelines on personal protective equipment, we need to increase awareness among doctors and the general public about their risks, and practicing good food safety habits (consuming pasteurized milk and milk products), washing hands frequently and thoroughly after contact with animals and their environment, among other measures of personal hygiene”.
In the USA, new controls on milk and derivatives: no live and infectious viruses
“No live, infectious virus was detected” as part of new checks carried out on milk and dairy products in the USA, where there is an ongoing epidemic of highly pathogenic avian influenza (HPAI) in cows. The Food and Drug Administration (Fda) announced this, reassuring consumers: “Pasteurization is effective in inactivating Hpai viruses”, pathogens of type A (H5) or A (H7). The agency also recalls that the definition of “highly pathogenic” for Hpai “refers to a serious impact on birds, not necessarily on humans”.
The results reported by the FDA refer to a national study launched in coordination with the Department of Agriculture (USDA) to verify the safety of milk on the market. The investigation was conducted on a total of 297 samples of dairy products sold at retail. The new data refers to 201 samples of milk and dairy products, including cottage cheese and sour cream, which the PCR analysis tested positive for the presence of viral fragments. These samples were then subjected to the gold standard analysis which allows us to detect the possible presence of infectious viruses. “Such additional preliminary testing did not detect any live, infectious virus,” the FDA stressed. “Together with previously communicated preliminary results from an initial series of 96 milk samples, these data confirm our assessment that the commercial milk supply is safe,” the agency reiterated.
Viral fragments had been found in one milk sample out of 5 subjected to PCR, but the agency immediately clarified that these were pieces of virus that were most likely inactive. The FDA also reassures on the safety of powdered milk and derivatives intended for infant feeding. All samples of retail products analyzed tested negative for the PCR test, indicating “the absence of viral fragments or HPAI viruses” in formula milk and derivatives. Therefore no further testing was necessary for these samples.”
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