Covid, what are the most common variants today and how much they should worry us – Corriere.it

by time news

1 What is a variant?
The variant is a virus that has a precise number of mutations compared to the original strain. There have been thousands of variants in circulation since the early days of the coronavirus pandemic, but most are “neutral” because they do not benefit the pathogen. Others may contain more worrying characteristics because they increase the transmissibility of Sars-CoV-2, the pathogenicity (inducing more severe disease) or circumvent, at least partially, the immunity acquired following a natural infection or vaccine.

2 What are the variants that are most worrying?
The World Health Organization and the European Center for Disease Prevention and Control (ECDC) list four variants of concern, the so-called Vocs (Variants of concern). They are the English variant (B.1.1.7) today dominant in Europe; the South African (B.1.351); the Brazilian (P.1), and the second Indian strain (B.1.617.2). Eight other variants (including Nigerian and two other Indian strains) are classified of interest (VOI). There are scientific hypotheses, but still uncertain, that could have an impact on the transmissibility, severity and immunity of the virus. Another twenty variants are being monitored.


3 What are the characteristics?
English and Indian have been shown to have greater transmissibility; the African could induce a partial “immune escape” effect against some monoclonal antibodies which could also affect a slight reduction in the efficacy of vaccines; on the other hand, there are no certainties that the Brazilian can cause a high number of reinfections as emerged at first. However, the variants that have arisen so far are natural offspring of the virus’ adaptation to humans and none of them are particularly relevant in making approved vaccines less effective. If we do not stop the circulation of the virus (thanks to vaccination), however, we cannot exclude that in the future a partially vaccine-resistant strain may appear that would tend to spread even in a vaccinated world. But at the moment this variant fortunately does not exist.

4 How widespread are the variants in Italy?
The latest report from the Istituto Superiore di Sanità dated 18 May indicates that the English variant is still prevalent (88.1%), but down from 91.6% on 15 April. The diffusion of the Brazilian is growing (at 7.3% compared to 4.5%). The Indian is 1% (identified in 16 total cases). Nigerian and South African are under 1%. However, the photograph of the diffusion of variants is partial because Italy sequences only 1% of cases compared to 8-10% in the United Kingdom.

5 Why is there so much talk about the Indian variant?
Because it contains two already known mutations: E484Q and L452R which for the first time appear together. The first increases transmissibility by at least 50% according to the first available data. The second could give it the power to bypass the effect of the vaccine.

6 How widespread is it in Europe?
According to the Gisaid database, the Indian variant has been reported sporadically in almost all European countries. More worrying is the situation in the United Kingdom where in the last week a quarter more infections were recorded than the previous one and the cases of the Indian variant (7,000 confirmed) doubled in seven days with absolute numbers, however, contained. The Indian strain, however, despite being highly contagious, does not appear to cause serious disease.

7 Do Vaccines Protect Us From Variants?
The European Medicines Agency says that all four vaccines in use in Europe are effective against the variants, at least as far as serious disease is concerned. Studies on the complete vaccination cycle carried out in Israel and Qatar indicate a good, albeit less potent, response of the Pfizer and Moderna vaccines even against the most feared variants, in particular the South African. AstraZeneca seems to work less towards the South African, but there is a lack of consolidated data. A very recent analysis by Public Health England raised concern which, while highlighting the high efficacy of vaccines against the Indian variant, reported that after a single dose both Pfizer and AstraZeneca the protection is only 33%. However, the UK in emergency conditions chose to delay the second dose to immunize as many people as possible. We do not know if the increase in infections that the British are suffering is due to the arrival of the Indian variant or to the fact that the effect of the first dose is ending, which must always be enhanced with the second. At the moment there is no evidence that the Indian variant escapes standard vaccinations, even those delayed by a few days with respect to the protocols, as we are doing in Italy.

May 31, 2021 (change May 31, 2021 | 07:32 am)

© REPRODUCTION RESERVED

You may also like

Leave a Comment