The coronavirus for which covid vaccines were originally designed has been mutating.
The risk that the vaccines would lose efficacy against the new variants raised from the beginning the possibility of introducing changes in the composition of the vaccines.
Omicron has become so dominant that it was the candidate for a specific vaccine.
This Wednesday, the health authorities have approved a booster dose aimed at combating it and thus preventing covid from continuing to wreak havoc this fall and next winter.
The coronavirus continues to cause nearly 100,000 infections and 500 deaths daily in the United States, the only country in the world that has exceeded one million deaths from the pandemic.
Life expectancy has dropped the most sharply since World War II.
The president of the United States, Joe Biden, and the first lady, Jill Biden, are among those who have been infected with covid in recent weeks.
However, the incidence is now in a downward phase and covid is less and less dominant in public and political discourse.
In this context, the Food and Drug Administration (FDA, for its acronym in English) has approved an emergency authorization for bivalent vaccines or updated booster vaccines against covid from Moderna and Pfizer, the first for those over 18 years of age. and the second for those over 12. They must be administered in a single dose at least two months after the primary vaccination or the previous booster dose.
The FDA and the rest of the world's health authorities already have experience in authorizing vaccines against different strains of the flu, for example.
Saving the distances, it is a similar case.
These new vaccines contain two SARS-CoV-2 virus messenger RNA (mRNA) components, one from the original strain of SARS-CoV-2 and the other in common between the BA.4 and BA.5 lineages of the variant. omicron
The original covid vaccines administered to millions of people in the United States and around the world since December 2020 contain only one component of the original strain of SARS-CoV-2, which is why they are called monovalent.
With the approval of the new vaccines, it will no longer be possible to administer the original ones as booster doses, the FDA has decided.
The BA.4 and BA.5 lineages of the omicron variant are currently causing the majority of covid cases in the United States and are expected to be the most contagious this fall and winter.
The FDA expects that bivalent vaccines will provide greater protection against the omicron variant currently in circulation.
The administration of the vaccines can begin in a matter of weeks, as soon as the manufacturers have doses for it.
Side effects
The side effects that the new vaccine can cause are similar to those of monovalent vaccines.
Among study participants who received the bivalent vaccine, the most common side effects were pain, redness, and swelling at the injection site, fatigue, headache, muscle pain, joint pain, chills, swollen glands lymph nodes in the same arm as the injection, nausea, vomiting and fever, according to the FDA.
In June, the agency's Vaccines and Related Biologics Advisory Committee voted overwhelmingly to include an omicron component in booster vaccines against Covid.
Only two months after its formulation, the vaccines have been approved by the emergency route.
They use the same messenger DNA technology for which Moderna has recently filed a lawsuit against Pfizer and BioNTech alleging infringement of their patents.
"Covid-19 vaccines, including booster doses, continue to save countless lives and prevent the most serious outcomes, such as hospitalization and death," FDA Commissioner Robert M. Califf said in a statement.
“As we head into the fall and begin to spend more time indoors, we strongly encourage anyone who is eligible to consider receiving a booster dose with a bivalent COVID-19 vaccine to provide better protection against the variants currently circulating”, he added.
The mRNA in these new vaccines is a specific piece of genetic material that instructs the body's cells to produce the spike protein that differentiates the original strain of the virus from the BA.4 and BA.5 variants of omicron, which they share.