A completely new variant could be born and very distant from the Omicron strain, perhaps capable of exceeding the protection offered by vaccines
Why is the growth of infections in China an alarming figure for the development of new variants?
The probability of the variants appearing increases with the increase in the circulation of Sars-CoV-2. In China, some forecasts trace peaks of infections with abnormal figures: 3.7 million a day in mid-January and 4.2 million a day in March. RNA viruses like the coronavirus make certain mistakes, called mutations, every time they reproduce. In most cases the mutations do not lead to major changes. However, the more a virus circulates, the more likely it is that significant variants will arise, with characteristics of greater diffusivity or pathogenicity.
Why is the new wave of Covid so widespread in China?
Due to the zero Covid policy carried out by the Chinese government, the local population is practically naïve, i.e. they have had almost no previous exposure to the Sars-CoV-2 virus. Not only that: the elderly have been little immunized and the vaccines offered, Sinopharm and Coronavac, have proved to be much less effective than those used in Europe and the USA. Based on available estimates, only 25% of the Chinese population would have some degree of immunity to Omicron (from vaccine or infection). The virus is free to infect millions of people and to replicate and mutate millions of times.
What do world health authorities fear?
Especially the development and arrival of a variant that may not be derived from Omicron. In the first two years of the pandemic, the variants of concern belonged to different strains (Alpha, Delta, Beta, Omicron), but in the last year only subvariants of Omicron have developed. The problem is that in China, with such a high circulation of the virus, a completely new variant could actually be born and very distant from the Omicron strain, perhaps capable of exceeding the protection offered so far by the vaccines in use.
Is there a risk that a more lethal variant of the current ones will appear?
It is not possible to predict in which directions Sars-CoV-2 will evolve. So far it has moved towards greater transmissibility and Omicron is one of the most contagious viruses ever to appear. It could overcome the vaccine and immune system barriers and acquire greater pathogenicity. Omicron itself, as demonstrated by the full Chinese hospitals, is not so mild: as studies confirm, if it had not encountered a vaccinated population like the Western one (or in any case immune to the disease), it would have been as lethal as the Wuhan strain (but less so than the variant Delta).
How to prepare for the possible arrival of a new variant?
sequencing is essential to intercept new strains. Health Minister Schillaci has ordered the mandatory swab for all passengers from China. The measure serves precisely to ascertain the type of Covid variant present in those arriving from the Asian country. Vaccination boosters are also important, especially for frail people. In fact, it seems very unlikely that the protection given by vaccines can be completely eliminated, while it could decrease proportionally in those who have not received recent boosters (they are always possible after 120 days from the last immunization or positivity).
With the advice of Paolo Bonanni, epidemiologist, full professor of hygiene at the University of Florence
December 29, 2022 (change December 29, 2022 | 14:26)
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