In the USA the debate is already underway: Are we preparing for a possible avian flu pandemic? If the journal ‘The Lancet’ highlights the fundamental steps that should not be overlooked – from the rapid development of specific H5 tests to continuous virological analyzes to identify changes in the virus that could have an impact on adaptability and transmissibility, from the development and production of vaccines to clear and transparent communication with the public – overseas experts such as scientist Eric Topol point out that at the moment “all this is not being done very well” and it is necessary to “prepare” for the possibility of human-to-human transmission of H5N1 avian influenza . And is Italy ready? “We should have an updated pandemic plan. I believe it is ready, even if not yet approved, it seems to me. I hope it happens soon, clearly with adequate financing”, he highlights to Adnkronos Salute the epidemiologist Gianni Rezza.
“Topol knows the United States and knows better than us what is being done – reflects the former DG Prevention of the Ministry of Health, now extraordinary professor of Hygiene at the Vita-Salute San Raffaele University in Milan – I remember, however, that in United States, the H1N1 virus was identified in 2009, which had emerged in Mexico and was identified in California” and then in other states, before being declared a pandemic. “It is therefore difficult for me to think that the CDC”, US Centers for Disease Control and Prevention, “or those on their behalf are not able today to identify areas of human transmission. As regards preparation, however, I don’t know how are moving” the States. “In Italy the updated pandemic plan should be ready”, awaiting approval. “What is important is that exercises have been carried out, that there are sufficient supplies of what is needed and it is clear that on this front the fact that there was a recent pandemic helps, also in terms of flexibility to adapt needs to a ‘epidemic”.
What should be done in case of confirmed large-scale human-to-human transmission? “At that point – analyzes Rezza – everything should be activated in terms of response: stocks, including protective devices, vaccine distribution plan, diagnostic systems to promptly identify any circulation in our country too. All things that are foreseen also in this pandemic plan which I hope will be approved soon and, I repeat, with adequate funding”.
Will it be a pandemic? The future scenario and the “unforeseen ending”
Could an H5N1 avian flu pandemic, so close to Covid, really happen? “It’s not an obvious ending. I think it’s possible, I don’t know how likely. This virus has been circulating for 20 years. Now it circulates more frequently in mammals, it’s true, but it will adapt to humans enough to be transmitted efficiently from person to person. person? We don’t know. And, even if it were, would it maintain this virulence once it was transmitted from person to person? Would the alarmism” without clear elements “be harmful “Something really happens and no one believes it. It’s something that should be avoided, also because today it’s not like people have to do anything” to avoid any risks, “or they have to be scared about something in particular.” Rezza then explains, looking at future scenarios.
And, at Adnkronos Salute, he paints a picture of what could happen now, with the virus circulating more and more in mammals, such as dairy cows in the USA. “In the meantime – he analyzes – what matters is that” whoever will have to deal with the management of a similar event “does what needs to be done to make us ready and not be a step behind perhaps other countries. The problem today is, on the one hand on the one hand, to avoid the alarm and on the other to be prepared because there is no deadline for pandemics”, warns the former Prevention Director of the Ministry of Health and super expert on infectious diseases from the ISS (Higher Institute of Health). “It could happen a year or the following month, especially since they are different viruses: Covid was a coronavirus and this would be a flu. But it is not even certain that H5N1 will be the cause of the next pandemic. If you remember, in 2009 everyone expected an avian pandemic to come from the East and a swine pandemic arrived from the West. It wasn’t very serious, the elderly were protected.”
Therefore, Rezza continues, “let’s say that the pandemic epilogue is not yet written, it is not a given, because for now we do not have evidence of transmission of the infection from person to person. The virus does not seem to have made those mutations that adapt it completely to humans. Of course, there are reports that it first circulated in one mammal and then in another, there was the human case reported in the USA, monitoring is underway on other people , the questions are there. It is a phase in which we must not go too far, not for diplomatic reasons or to be cautious, but because there are no elements to say that there is an ongoing transmission or to exclude it. It is logical that those who have to deal with it must have the utmost attention, there is no doubt that we must continue to monitor. The case of human-to-human transmission can also occur, but if the virus is not well adapted and is not transmitted efficiently from one person to another. otherwise, we won’t have sustained transmission.” The framework “should be defined and then we will see. At a certain point, the crux of the suspected cases should also be clarified. For now there are a whole series of questions that still require answers”.
Pre-pandemic vaccine, the option is there
If a vaccine were to be needed, in the event that an H5N1 epidemic developed in humans, “the problem would not be to develop a vaccine against avian influenza that would be ‘humanised’, but rather to produce it on a large scale in a timely manner In this regard, there are two companies that have already produced pre-pandemic vaccines based on H5. If a slightly different variant began to circulate, it could be easily adapted , but to an influenza virus, albeit an avian one. And there have been vaccines against influenza viruses for decades”, explains Rezza.
“The experience is there, we know how it works – he assures -. We are not faced with a completely unknown virus for which there have never been any vaccines adapted. But it is clear that large-scale production is no joke. And in fact, the WHO says that it would take 4-6 months to distribute the doses because there is a ‘scale up’ of production to be done. Now there are also different platforms and perhaps others could be added to the classic technologies classic platforms there are at least two pre-pandemic vaccines that could be easily adapted.”
“The global partnership Cepi”, Coalition for Epidemic Preparedness Innovations, “highlighted that we must ensure that next time we have the vaccine in 100 days, because every extra day counts. The problem, in this case, would be production on a large scale. As for Italy, when I was in the ministry we opted for one of these pre-pandemic vaccines in a European joint program. It is clear that as a country we must be ready. And being ready also means having the option to possible pandemic vaccines”.
Human-to-human transmission, the point
“It’s not easy to fully understand the situation right now” with the H5N1 avian influenza A virus. There are several aspects still to be clarified before going unbalanced on what the present is and what the future will be, explains Rezza further. “This virus, which now has migratory birds as its natural reservoir, has been circulating since at least 2003, therefore 20 years – recalls the epidemiologist – Starting from 2004-2005 it began to cause sporadic human cases in people who came into contact with chickens and birds from courtyard infected by migratory birds. Women and children who looked after these courtyard animals, in countries where there was a subsistence economy based on this type of activity, became infected with a high lethality In the 2000s there was the first relevant episode of human-to-human transmission in Sumatra, Indonesia”.
It was April-May 2006: “A woman” who caught the infection from a sick animal “infected 6 members of an extended family and one of these in turn infected another person, another member of the family: three generations of cases After that, the vast majority of cases identified since then, a few hundred, have occurred in which the virus has never acquired the ability to transmit from person to person efficient manner”, points out Rezza. The Sumatra precedent “seems to be the most important episode. It must be said that other avian viruses, for example H7N7, also gave rise t
o small epidemic outbreaks but they stopped there”. What happens now? “For some time this virus has apparently begun to circulate among mammals: minks, dogs, cats, and now in cows, among which there appears to be a fairly extensive epidemic in the USA. A case has also been identified in the United States human, that hemorrhagic conjunctivitis reported in the magazine ‘Nejm'”.
But now, he continues, “it has also been explained that there would be around 300 suspected cases under observation, monitoring and testing, but we don’t know if some of these are actually positive”, recalls Rezza. The WHO itself, taking stock a few days ago, had cited at least 220 people monitored and 30 subjected to tests, also highlighting that many more were exposed to infected and potentially at-risk animals, therefore the importance of everyone being tested or monitored . “Even in this case, the fact that there are other cases would mean little, assuming that this is the case – reasons Rezza – because the main question would remain: whether these cases, that is, are due to human-to-human transmission or are in any case all people who have been to contact with infected cows. They must be monitored and tested, it is not certain that they are cases of H5N1 and in any case the hypothesis that there is human-to-human transmission should still be verified.
What is known about the H5N1 virus today, after its circulation in mammals? “The molecular analyzes that some English evolutionary biologists have done, for example, do not yet show a great adaptation of the virus to humans, honestly – observes Rezza – This virus”, according to these analyzes conducted on its evolution, “would have even greater affinity for the ‘deep’ receptors, those found in the lower respiratory tract. It is therefore difficult to say what will happen. And it is difficult to say whether this virus will adapt to humans enough to become transmissible from person to person. Can it not be ruled out? ? We do not know”.
Another aspect that Rezza focuses on are the fears expressed by some experts about the risk that a virus with a high lethality, even 50%, could spread. “But, once again, it is not certain – he specifies – It is not certain that a virus that adapts to humans will subsequently maintain its characteristics of high virulence. It could do so and it could not do so. We don’t have too many certainties at the moment. A final element is how a virus adapts to humans. Either it adapts by making small mutations that give it a greater affinity for receptors in the upper respiratory tract, in the throat, so that it is transmitted more easily from person to person. for example, in a host like the pig, which is receptive to both human and avian viruses, it could make a rearrangement, that exchange of gene segments that influenza viruses generally sometimes do.” This is why, for the expert, it is too early to say how it will go. “At the moment it is a situation in which any alarmism is out of place, also because now we cannot do anything other than observe, monitor, test and prepare”, he concludes.
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