As part of ongoing efforts to mitigate the effects of Covid-19, the U. S. Food and Drug Administration is not working to protect the effects of Covid-19. The U. S. government approved the emergency use of new Covid-19 vaccines. In addition, the Centers for Disease Control and Prevention has new recalls for any older ones. of 6 months. These new formulations are better suited to the virus strains circulating lately. And as with vaccines approved in the past, we expect them to reduce the rate of serious illness, hospitalizations, and deaths among those infected with SARS-CoV. 2, the virus that causes Covid-19.
The new vaccines, developed through Moderna and Pfizer-BioNTech, use the same mRNA-based generation as in previously approved versions of their vaccines. However, the mRNA itself has been modified to reflect the evolution of the virus. The latter vaccines involve mRNA. encoding the spike protein of the omicron subvariant XBB. 1. 5. Preliminary data show that this withdrawal will trigger the production of antibodies that detect this form of SARS-CoV-2. This recall would possibly also provide improved coverage unlike other circulating subvariants.
As we have seen in the pandemic, the virus evolves over time. The first Covid-19 vaccines, approved for use in December 2020, contained an mRNA segment encoding the spike protein of the original SARS-CoV-2 virus. However, over time, viral variants appeared that contained mutations in the gene encoding the spike protein. These mutations have negatively affected the efficacy of the original vaccines and have led drug brands to expand new formulations to target more new virus strains.
In reaction to the accumulation of Covid-19 cases related to the omicon variant, for example, Moderna and Pfizer-BioNTech have switched their monovalent vaccines to bivalent vaccines. Approved for use in August 2022, those booster doses contained two fragments of mRNA. one encoding the spike protein of the original virus and another encoding the spike protein of the dominant subvariants BA. 4 and BA. 5 of omicron worldwide at that time. However, by the end of 2022, the prevalence of these subvariants had decreased and a new omron subvariant, XBB. 1. 5, appeared. The prevalence of this subvariant has been accumulating, leading to the progression of new Covid-19 vaccine formulations.
But XBB. 1. 5 is no longer the dominant variant. In May 2023, XBB. 1. 5 accounted for about a portion of all Covid-19 infections in the United States. By July, that figure had fallen to less than a quarter. Today, XBB. 1. 5 accounts for less than 5% of infections. Meanwhile, the prevalence of the micron subvariant, EG. 5, has increased. This variant now accounts for about 25% of all infections.
And researchers are eagerly tracking another subvariant, BA. 2. 86. Also called Pirola, this subvariant was first detected in Denmark in July 2023. Since then, it has been detected in 15 countries in addition to the United States, according to the foreign virus-tracking site. GISAID. So far, the prevalence of this variant has remained low. But scientists are still involved because of the huge number of mutations it has, especially within the Spike protein gene. Some researchers fear that this constellation of changes may allow this variant. evade existing vaccines and be more transmissible than their predecessors.
So, is the XBB. 1. 5 vaccine already obsolete? In a press release issued on September 6, 2023, Moderna announced that trial participants who received its XBB. 1. 5-based vaccine generated neutralizing antibodies opposed to EG. 5 and BA. 2. 86. In other words, this new vaccine has effects on the production of antibodies that recognize the newly dominant subvariant and a potentially worrisome subvariant. In addition, in a manuscript that is currently under peer review, researchers from Harvard University and Los Alamos National Laboratories report that, despite its many mutations, BA. 2. 86 may not possibly be as able to circumvent immunity as first feared.
In fact, this new vaccine will offer greater coverage than existing vaccines against the Covid-19 strains circulating lately. But what happens next? The virus will continue to evolve. That’s for sure. Therefore, for the foreseeable future we can probably expect updated versions of Covid-19 to be published periodically, in reaction to the new variants, but perhaps that will change. Researchers at institutions, such as the Duke Human Vaccine Institute, are actively seeking to expand a pan-coronavirus vaccine, one that may well inhibit several other coronaviruses. However, until this purpose becomes a reality, we risk getting caught up in a perpetual game of cat and mouse.