In other words, the COVID-19 MESSENGER RNA vaccines are being modernized. The new booster doses being distributed this week in the United States and Europe are designed to counteract the Omicron strains that are now spreading.
According to experts in the medical field, these will be more effective in warding off future strains of SARS-CoV-2 than the previous shots, which were developed in response to the initial detection of the virus in late 2019.
The coronavirus has undergone continuous evolution since its discovery. These changes have made it more contagious and resistant to the immune responses prompted by primary vaccinations and subsequent boosters. Unfortunately, our vaccines haven’t changed despite the fact that Omicron and its variants are the most contagious we’ve seen so far.
Ross McKinney, chief scientific officer at the Association of American Medical Colleges, puts it this way: “Basically, we’re attempting to catch up with a virus that keeps evolving.” And although we can’t see into the future, we can hold out hope that the next version will emerge from BA.4 or BA.5. Therefore, it would be beneficial to have antibodies that defend you from that.
Omicron has multiple subvariants, including BA.4 and BA.5. According to the CDC, as of September 3rd, BA.5 accounted for an estimated 88.6 percent of all Covid-19 cases in the US, whereas BA.4 accounted for only 2.8 percent. About 8.4 percent of cases are now associated with a new BA.4 offshoot called BA.4.6.
The new US formulations, developed independently by Moderna and Pfizer, are effective against the ancestral strain of the virus in addition to BA.4 and BA.5. Bivalent vaccinations contain two different messenger RNA sequences that direct cells to produce the viral “spike” protein shared by the parent strain and the two variations.
Although BA.4 and BA.5 both have spike proteins, they have undergone scores of changes that make it simpler for them to bypass disease-fighting antibodies generated in response to earlier vaccinations or illnesses.
Professor of infectious diseases at the University of California San Diego School of Medicine Robert Schooley explains, “Over time, the virus has progressively mutated such it looks less and less like the virus that started in the human population.”
In order to stimulate the human immune system to recognize the older versions, our vaccines must continue to resemble the older forms.
The FDA issued expedited approval for variant-specific boosters developed by Moderna and Pfizer-BioNTech on the same day, August 31. The Centers for Disease Control and Prevention (CDC) soon after recommended vaccinations for everyone living in the United States.
A bivalent version, effective against both the original virus and the Omicron form BA.1 that took over last winter, has also been authorized by the European Medicines Agency and the UK’s health agency.
Those 12 and up who have already finished their primary immunization series or a previous booster can get a fresh bivalent booster right now. The Centers for Disease Control and Prevention (CDC) advises waiting at least two months between doses of any vaccine (two doses of the Moderna, Pfizer, AstraZeneca, or Novavax vaccines, or one dose of the Johnson & Johnson vaccine).
The CDC recommends waiting three months after the onset of symptoms before giving a booster shot to anyone who has recently been exposed to Covid-19.
However, the efficacy of the BA.4-BA.5 enhancers is still up for debate. The Food and Drug Administration has stated that widespread clinical trials are unnecessary for these variant-specific enhancers.
Instead, manufacturers can follow the yearly flu vaccine’s lead and do smaller studies to prove that the new formulations actually work by eliciting an immunological response in humans.
Both Moderna and Pfizer tried out bivalent vaccines against the original virus plus BA.1. As a result, BA.4 and BA.5 eventually replaced BA.1. Both firms were asked by the FDA to change their product focus to developing a formulation that would eliminate the more recent variations.
Animal data and trials of BA.1 bivalent vaccinations were sufficient for regulators to give the OK to the BA.4 and BA.5 bivalent vaccines, even though studies evaluating their efficacy are still underway.
Academic researchers revealed that Moderna’s BA.1 bivalent vaccine elicited higher levels of antibodies against Omicron than the original immunizations in a study of approximately 600 participants that have not yet been peer-reviewed. Moderna and Pfizer’s BA.4 and BA.5 formulation trials in mice also showed an improved immune response to those versions.
Researchers don’t anticipate any problems with the new vaccination boosters because the mRNA technology used to create them is identical to that used in the original immunizations.
Associate professor of epidemiology at the University of Michigan School of Public Health Aubree Gordon says, “Part of the rationale to want to get this out as quickly as possible is because we’ve got the autumn season coming.”
Infections with Covid-19 and hospitalizations due to the virus have spiked drastically over the past two winters, but public health officials are hoping to prevent a repeat this season.
The release of a vaccine that induces immunity against the circulating variations is crucial if we are to reduce the prevalence of illness in the general population, she explains.
What Do the New Boosters Contain?
Coding for the spike protein of two separate COVID-19 strains is included in these revised booster injections.
One will target the spike protein of dominant Omicron variants BA.4 and BA.5, and the other is the original strain that was used in the first vaccines (both at 50%). Bivalent describes this kind of situation.
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Why Do the New Vaccines Still Contain Spike Protein Targeting the Original Strain?
This bivalent strategy has been demonstrated to stimulate a more robust immune response. We’ll be more protected from the strains that are presently circulating, and our immunity to the initial strain will be preserved. It may also mean a stronger defense against as-yet-unseen varieties.
Scientists at the University of Rochester Medical Center remark in a study comparing various strain-specific vaccines that the next variety to develop may very well be more closely related to the original strain, giving this new booster the potential to be more effective.