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Vaccines and their efficacy against the Delta variant

Delta is already present in more than 70 countries, especially among unvaccinated people.

This article was translated from our Spanish edition using AI technologies. Errors may exist due to this process.

We all watched the news: a new variant of the SARS-CoV-2 virus was found in India in October 2020, sparking a devastating second wave with more than 400,000 daily infections.

This mutation called B.1.617.2 , better known as the Delta variant , has brought new waves of the pandemic in different parts of the world.

Delta is already present in more than 70 countries. It is responsible for 90% of cases in the UK; the United States Center for Disease Control and Prevention (CDC) indicates it as the predominant cause of new COVID-19 infections and in Mexico it has also been detected in younger groups of people, most of whom have not received the vaccine.

According to a press release from Houston Methodist Hospital , the Delta variant causes more hospitalizations and as a bonus, a derivative of the Delta variant, called Delta Plus, has been detected which has an additional mutation in the spike protein.

There are hundreds of variants of the coronavirus, but only a few stand out

According to the Houston Methodist Hospital, the World Health Organization (WHO) has grouped the variants into two broad categories: variants of concern (the most infectious) and variants of interest.

The Delta variant is more contagious and infects young people in a greater proportion than others, mostly in unvaccinated people .


Faced with the growing emergence of new cases of the Delta variant, Dr. Randall Olsen, medical director of the Molecular Diagnostic Laboratory at Houston Methodist Hospital, explained that, “for reasons that we do not yet understand, a person infected with the Delta variant has almost twice as likely to transmit the virus as a person infected with another variant. "

The symptoms of the Delta variant are similar to those of other respiratory infections, therefore it is recommended that anyone with cold symptoms undergo PCR testing for COVID-19.

Regarding precautionary measures, the Houston Methodist Hospital specialist assured that “the contagion rate among vaccinated people is very low and when the disease occurs it develops asymptomatically or very mildly. We must encourage everyone to get vaccinated. Vaccination is the only way to get out of the pandemic positively. "

Vaccines and their effectiveness

At the moment, the six vaccines that have received authorization for emergency use by the WHO (Sinovac, Pfizer / BioNTech, AstraZeneca / Oxford, Janssen, Moderna and Sinopharm) are effective against all variants of COVID-19.

With a single dose of vaccine, the protection against the Delta variant is 33%. After the second dose, the percentage of prevention increases between 60-80%, depending on the vaccine.


Because the Delta variant, and other variants currently circulating, are highly transmissible, it is advisable to follow the prevention measures that were established at the beginning of the pandemic: Use of face masks, healthy distance of 2 meters, avoid closed public places or very busy and constant hand washing.

It is very important to continue with the established hygiene measures and, above all, it is absolutely essential to get vaccinated.