Vaccines from Pfizer and Moderna are less effective against Delta variant

According to very recent information, the Delta variant is responsible for 100% of infections in all regions in Portugal. Being vaccinated against COVID-19 does not mean that you are fully protected. As we know, vaccines protect the severe form of COVID-19 disease and for that reason alone it is a huge advantage.

A recent study by the Doctor Ricardo Jorge National Health Institute (INSA) reveals that mRNA technology vaccines (Pfizer and Moderna) are less effective in preventing infection by the Delta variant of the SARS-CoV-2 coronavirus.

Efficacy of mRNA vaccines is lower than Delta variant

According to the INSA report, the Delta variant (B.1.617.2) has a relative frequency of 100% in the week of August 9-15 in all regions, according to data collected to date.

Regarding vaccination, in research, which is in pre-publication and has not yet been subject to peer review, it is concluded that there is "significantly higher probability of Delta variant infection in vaccinated persons", sensibly "double the risk of infection by the Alpha variant".

This trend in the effectiveness of mRNA vaccines compared to the predominant variant in Portugal is the same in people with one dose or with both doses of the complete regimen. For the study, approximately 2,000 positive cases of infection were analyzed.

INSA: Pfizer and Moderna vaccines are least effective against Delta variant

According to the results obtained, it was observed that those infected with the Delta variant had, on average, higher viral load values, which could mean greater transmissibility", reveals the INSA.

The effectiveness of the complete vaccine schedule, which was 70% to 90% for the Alpha variant, is estimated to drop to 41% to 80% for Delta. In the case of a dose, the effectiveness of 55% to 70% against Alpha will increase to between 24% and 49%, suggest the results of the INSA study.

Another key result of the study indicates that people with two shots of vaccine have "lower viral load and potentially lower transmissibility than unvaccinated individuals" for both variants of SARS-CoV-2.

In the specific case of Delta, transferability is equivalent whether there is only one outlet or both.

The study was carried out between May and July this year, when the Delta variant became predominant in Portugal.