There is evidence that, in addition to being safe, these combinations enhance the immune response

It is not the first time we are hearing about mixing vaccine doses against Covid of different technologies (adenovirus and messenger RNA). 

The US Food and Drug Administration (FDA) approved a “mix and match” method last week for those who need a booster shot of a Covid vaccine after their primary series.

“The FDA has determined that the known and potential benefits of the use of a single heterologous booster dose outweigh the known and potential risks of their use in eligible populations,” the agency said in a statement.

The Pfizer, MIn the United States, Pfizer, Moderna, and Johnson & Johnson vaccines are approved. Now, a single shot of any of them may be administered following completion of primary vaccination with a different Covid vaccine.

Individuals who first had two Moderna shots who are 65 years of age or older, over 18 years of age and at high risk for Covid, or over 18 years of age and have significant occupational exposure may now get a booster.

Adults who had the J&J vaccine – a single dose more than two months ago may also get a booster.

Previously, only those with weakened immune systems or those who were elderly or members of high-risk groups and had previously got the Pfizer vaccine were eligible for a booster shot.

The data supporting the decisions come from emerging research reviewed by the FDA.

Not only in the United States but in other countries the mixture of vaccines of different technology has also been studied and the essence behind these studies is that combinations make the response more intense than when using a single method.

New research from Spain showed that there was no risk by combining two different drugs and it also increased the presence of neutralizing antibodies.

The most effective vaccines

Almost half a year later, The Spanish group has published an analysis that assesses the effectiveness of vaccination against symptomatic infection, hospitalization and death in Covid-19 cases of people between 50 and 59 years old, with the onset of symptoms between 1 and 30 August 2021, vaccinated with Janssen, Pfizer, Moderna or AstraZeneca.

The main conclusion of this report is that the Moderna vaccine achieves the highest vaccination effectiveness against infection and symptomatic infection (87% and 89%), followed by Pfizer (77% and 78%), while for the AstraZeneca and Janssen is lower, 68% for AstraZeneca versus both events and 64% and 56% for Janssen, respectively.

But protection against hospitalization is greater than 95% for all vaccines and slightly less for Janssen (86%), while death follows a similar pattern, although estimates have only been obtained for Moderna and Pfizer (<95 %) and for Janssen (89%). 

Regarding the heterologous AstraZeneca / mRNA regimen, the effectiveness is high against infection (90%), symptomatic infection (86%) as well as against hospitalization (98%).

Regarding the announcement now to mix Janssen with Pfizer or Moderna, the study authors assure that “we already have evidence of a heterologous pattern mixing vaccines of different origin (adenovirus and RNA) and it has been seen that in addition to being safe, it has even improved the immune response in these individuals”.

“From a technical point of view, adenovirus and RNA vaccines have the same information, what differentiates them is the vehicle (adenovirus or liposome) to reach their goal. The population has to be calm,” according to the study authors.

Authors also consider that the most important thing to measure the success of immunization is the result in the prevention of hospitalization and death, where all vaccines have shown high effectiveness.

All the trials that have been done with heterologous vaccination (mixing vaccines of different technology) go in the same direction: it greatly enhances the response. The evidence is that mixtures are enhancers. There are quite a few people with combined patterns all over the world, conclude the study authors.

Image Credit: Getty

You were reading: Why mix Janssen’s vaccine with an RNA vaccine (Pfizer or Moderna)?