A new vaccine directed against the so-called “South African variant“(501 Y.V2): Moderna developed it, delivering some doses to the US National Institutes of Health for the start of the clinical trial that tests efficacy and safety. The vaccine is called mRNA-1273.351.
Two possible strategies
The American company has outlined two strategies to deal with the more “bad” variants. The first involves booster doses to increase immunity. Three approaches have been identified: a candidate booster specific for the South African variant (mRNA-1273.351); a multivalent recall candidate which combines mRNA-1273 (the vaccine developed by Moderna against the original strains) and mRNA-1273.351 in a single vaccine (called mRNA-1273.211); a third dose of mRNA-1273 as a booster. The second strategy involves evaluating mRNA-1273.351 and mRNA-1273.211 as the primary vaccination for those who have not yet been vaccinated.
We are delighted to begin the clinical study on our booster variant and are grateful for the collaboration of the National Institutes of Health – he said Stephane Bancel, CEO of Moderna -. By leveraging the flexibility of our mRNA platform, we are moving rapidly to test vaccine updates that address emerging variants of the virus. We hope to show that booster doses, if necessary, can be done at lower doses: this would allow us to provide many more doses to the international community by the end of 2021 and into 2022.
Short time for authorization
The approval process for vaccines “adapted” to the new variants will be faster, at least in the United States: tests on a few hundred people like those that are done every year for the flu shot will suffice. This was announced by the Food and Drug Administration (Fda), presenting the new guidelines.
The third dose hypothesis
Other vaccine manufacturers are also gearing up against the variants. Pfizer e Biontech (messenger RNA-based vaccine, such as Moderna’s) are evaluating whether to add a third dose and studying a new version of the vaccine that is effective against the South African variant. The strategy announced by AstraZeneca is identical, whose vaccine uses the viral vector technique.
The among variants monitored
There are three variants that are most worrying: in all three cases the virus has mutations on the Spike protein, which the virus uses to enter cells.
The “English variant” (VOC 202012/01) it was first isolated in September in Great Britain. It has a higher transmissibility and was hypothesized increased pathogenicity, but so far there has been no evidence of a negative effect on vaccine efficacy.
The “South African variant” (501 Y.V2) was isolated in October in South Africa, while in Europe the first case reported dates back to 28 December. It has a higher transmissibility and from early studies it seems that it may decrease the effectiveness of the vaccine. We are trying to understand if it can cause reinfection in subjects already recovered from Covid.
The “Brazilian variant” (P.1) it was first isolated in January in Brazil and Japan. At the end of January it was reported in 8 countries, including Italy. A higher transmissibility is hypothesized and from the first studies it seems that it may decrease the effectiveness of the vaccine. Like the “Brazilian”, it could cause reinfection in healed subjects.
February 25, 2021 (change February 25, 2021 | 15:37)
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