Experts fear that with the high circulation of the virus, totally new variants could emerge capable of circumventing the effectiveness of vaccines on severe disease and slowing down the endemization phase of the virus
The sudden explosion of infections in China is worrying the World Health Organization, which even just a few days ago saw the end of the Covid-19 pandemic as imminent since with vaccines and therapies almost the whole world is living with SARS- CoV-2. However, the new massive wave of infections in China after the abandonment of the zero Covid policy is now very worrying the WHO which has asked Beijing for more precise data on infections, hospitalizations, deaths to assess the seriousness of the situation and the far from remote risk that new immunoevasive variants will emerge.
On the one hand, the government minimizes, ensuring that there have been no deaths from Covid after changing the counting criteria (i.e. only those directly attributable to respiratory failure caused by the virus are calculated), but on the other hand, hospitals in megalopolises arrive dramatic testimony with saturated intensive care and distressing coffin queues in front of the crematorium ovens.
The risk of a million deaths
According to a new study, China may face more than a million dead in 2023after the rapid change of course and the abandonment of the zero Covid policy which has so far kept infections and deaths relatively low in a Country inhabited by 1.4 billion of people. precisely for this reason it seems difficult for WHO to talk about post-pandemic when such a significant part of the world is entering its second wave, he told the Guardian
Marion KoopmansDutch virologist, WHO consultant.
The virus runs in a poorly vaccinated population
In this dramatic scenario, WHO and scientists from all over the world are alarmed not only by the explosion of cases and hospitalizations that are putting a strain on health care in China, but also on the possibility that new variants will emerge, even more efficient than Omicronif the virus will continue to run as it is doing in a poorly (and poorly) vaccinated population like China. In China, even the elderly, who are more vulnerable, are undervaccinated – he comments Paul Bonanni, epidemiologist, full professor of Hygiene at the University of Florence – and among other things, the products used have proved to be ineffective. Based on available estimates, only 25% of the Chinese population has some degree of immunity to Omicron (vaccine or infection): the rest of the population has not yet had contact with the virus, but will do so shortly with a single explosion.
The zero Covid policy
The advantage of the zero-Covid policy until a few days ago in China is clear: limiting infections. However, in this way no one will become immune, unless highly effective vaccines are offered. Anthony Fauci, presidential physician and outgoing director of the National Institute of Allergy and Infectious Diseases, said about China that limiting the movement of citizens can be beneficial until the majority of the population, especially the highly vulnerable elderly, can be vaccinated . But this didn’t happen in China: the elderly have been under-vaccinated and the vaccines offered, Sinopharm e
Coronavac
they are less effective against severe disease than Pfizer and Moderna.
The low immunity in China
So because of the continuous zero tolerance policy and at the same time poor vaccination of the population in China, a country which has effectively remained frozen in time, there is relatively low immunity to infections compared to the rest of the world. Today the Chinese population practically immunologicamente naive as was the world in early 2020, except that Omicron is far more contagious than the Wuhan ancestral strain and later ones.
Omicron no less dangerous
The boom in infections, hospitalizations and deaths that we are observing in China represent proof in the field that Omicron has not weakened as many believe. When Omicron hit Europe and the United States in late 2021 the new variant seemed relatively mild, but not because Omicron with its mutations has become less lethal. Rather, his aggressiveness is confronted with an immune system trained by vaccinations or infection and for this reason Omicron’s gravity is attenuated, explains Bonanni. Now there is also a newly published study which concludes that if Omicron had not encountered a population as vaccinated as the Western one or otherwise immune to the disease, it would have been as lethal as the Wuhan strain (but less than Delta).
The risk of new variants
But why are experts alarmed by the risk of new variants? In 2020 the whole world was a green prairie to the new Sars-Cov-2 and the entire world population had no immunity to the virus. The Wuhan strain spread all over the world, mutated randomly, then giving rise to other increasingly contagious variants and subvariants. However at the beginning of the pandemic, the virus did not encounter resistance to immunity: vaccines did not yet exist and in many countries lockdown or curfew policies had been implemented which limited the movement of people and consequently the transmission of the virus.
But now in China, which has almost one and a half billion inhabitants, they are circulating at a rapid pace several subvariants of Omicron and, according to experts, inevitable that new strains will emergealso with an increased reproductive advantage over previous variants. In fact, the probability of the variants appearing increases with the increase in circulation of the virus. RNA viruses such as the coronavirus, – explains Bonanni – make mistakes every time they reproduce, but in the majority of cases the mutations do not cause important changes in the structure of the virus. However, in probabilistic terms, the more a virus circulates, the more likely it is that significant variants such as greater diffusivity or pathogenicity will arise: as with the slot machine, the more attempts are made, the higher the probability that a more diffusive, or even more aggressive, combination will emerge.
The fear of going back
While in the first two years of the pandemic new variants with different strains (Alpha, Delta, Beta, Omicron) were created, in the last year only subvariants of Omicron have developed – explains the epidemiologist – which represent a signal of an endemisation trend of the virus thanks to vaccines that have proven effective against severe disease also against Omicron subvariants. The problem today is that in China, with such a high circulation of the virus, it could actually born a completely new variant and very distant from the Omicron strain maybe capable of overcoming the cross protection that vaccines have offered us so far. We would then find ourselves in a more dangerous situation, than sotit could lead us to levels of severe disease, hospitalization and death that we have not known for a long timeline Paolo Bonanni. A return fire that today would be difficult to digest. We cannot predict whether such an event will happen – clarifies the epidemiologist – and unfortunately it is not predictable. Among other things, with China’s lack of data, any prediction is even more difficult. What we can do today vaccinate us with the fourth doses to increase the protection eoProvide effective medical aid to China also against Omicron such as Pfizer and Moderna vaccines and antivirals. Aid that Chinese President Xi Jinping does not seem willing to accept. The pandemic has taught us that the virus has no borders and a new variant in our globalized world could quickly spread everywhere, concludes Bonanni. Will everything start again from China?
December 22, 2022 (change December 22, 2022 | 5:35 pm)
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