The coronavirus has not disappeared from the world and probably will not disappear, so some laboratories have already developed vaccines that match the mutations of the virus.
The United Kingdom was the first to enable the use of a new formula developed by Moderna for its messenger RNA vaccine in mid-August, which was improved to combat the omicron lineage in all its known subvariants.
The United States followed suit on the last day of August by authorizing the use of the updated vaccines from Moderna and Pfizer/BioNTech, which also uses messenger RNA technology, and within days began administering them to the general population.
Canada then approved Moderna’s updated SARS-CoV-2 coronavirus booster.
At the beginning of September, the British regulator gave the go-ahead to the updated version of Pfizer/BioNTech and at that time the country began injecting the new doses to people over 50 years of age, to those at high risk of any age, to pregnant women and health personnel.
And more recently, this Monday, the European Medicines Agency recommended the use of the updated Pfizer/BioNTech vaccine in the 27 countries of the European Union, a decision that the European Commission must adopt in the coming days.
What is a bivalent vaccine?
Bivalent vaccines are those that protect the body against two types of antigens.
In the case of the updated doses against covid-19, they are bivalent because they immunize against the original strain -also known as Wuhan after the Chinese city where the virus appeared- and against the omicron variant.
The vaccines used until now in the world were monovalent, that is, they were designed only against the original virus.
A widely used bivalent vaccine in Latin America is the one against the human papillomavirus (HPV), which was designed for types HPV-16 and HPV-18.
vaccinations they can be versatilemeaning they can be designed for multiple strains or even multiple diseases.
The vaccine pentavalentfor example, is applied to children and protects against diphtheria, whooping cough, tetanus, type b infection, hepatitis B or polio, depending on its formulation.
What are updated vaccines made of?
Each dose of Pfizer’s original vaccine against covid-19 contained 30 micrograms of tozinamemer, a substance that acts on RNA, in 0.3 milliliters of liquid.
The bivalent version also contains 30 micrograms, although in this case 15 micrograms are designed for the Wuhan strain and the other 15 micrograms for omicron.
In the case of the compound formulated by Moderna, each dose of the monovalent product contained 50 micrograms of elasomeran in 0.5 milliliters that targeted the initial virus, while the updated booster contains 25 micrograms that targeted each variant.
For now, the updated Pfizer/BioNTech booster is licensed for ages 12 and up and Moderna’s is licensed for ages 18 and up in both the US and UK.
The licensed bivalent vaccines in the US were designed to target the BA.4 and BA.5 lineages of omicron, although it covers earlier variants.
A previous version targeting the BA.1 lineage of omicron was approved in the UK.
US health officials have noted that a annual booster of the anticovid vaccinein the same way that is done with the flu vaccine.
Do the new vaccines replace the first ones?
Vaccines against covid-19 began to be administered in the world in December 2020.
Since then, more than 12,000 million doses from a dozen laboratories were applied.
Almost two years later and given the predominance of the omicron variant, the laboratories were commissioned to design the updated versions.
However, these new vaccines do not replace the initial scheme, which was intended only for the Wuhan strain.
The bivalent vaccine is a booster, so those who have not been vaccinated with the complete schedule should do so before receiving this additional dose.
In the United Kingdom, at least three months must have passed since the last dose was received, while in the United States the minimum period is two months.
It doesn’t matter what vaccine a person has received before; the upgraded booster can be from either of the two labs that already have approvaldrug regulatory bodies said.
What happens in Latin America?
At the moment, no country in the region started vaccination with the updated versions.
But in Chile the government is thinking of a fifth anticovid dose – it has already given reinforcements of the third and fourth doses – with the bivalent vaccine that will begin to be given before the end of the year, the Minister of Health of that country, María Begoña Yarza, told him. to the local station Tele13 Radio.
The Latin American countries that have administered Pfizer/BioNTech vaccines so far are Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Dominican Republic, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, and Uruguay. .
Moderna’s vaccines, meanwhile, have been administered in Argentina, Bolivia, Brazil, Chile, Colombia, El Salvador, Honduras, Mexico, Panama, Paraguay and Peru.
A spokesman for the Moderna laboratory told BBC Mundo that the company modified the supply agreements with Argentina and Peru so that the dose deliveries are of the updated formula once they obtain the approval of the regulator in each country.
BBC Mundo contacted Pfizer to learn about its plans in Latin America, but received no response at the time of publishing this article.