Skip to main content


15 September 2021


Since the beginning of the pandemic, our teams have been on the frontlines of Covid-19 testing and diagnosis. We have relentless performed PCR, antibody, and antigen tests – and our data has helped the medical authorities track the spread of variants – helping them put in place targeted measures to contain the virus.

As the virus mutated, Unilabs introduced new techniques and technologies to improve, speed up, and broaden testing. This included tests that specifically identify variants such as the Delta and Delta-plus variants, as well as new kinds of tests like saliva or gargling tests.

In the fight against the more contagious Delta variant, our team in Portugal recently participated in a study carried out by the National Institute of Health Doutor Ricardo Jorge (INSA) and the health authorities, to determine the effectiveness of the mRNA vaccines (for example the Pfizer and Moderna vaccines) against the virus. Other types of vaccines were not part of the study. 

The study concluded that the studied vaccines are less effective against the Delta variant, compared to the Alpha variant.

The risk of a Delta-variant infection among the vaccinated population was approximately double the risk of an Alpha-variant infection, and that was true of individuals with both partial and full vaccinations.

Those infected with the Delta variant had, on average, higher viral load values, which is likely to mean greater transmissibility.

The study also revealed that the double-vaccinated had lower viral loads and potentially lower transmissibility than unvaccinated individuals, for both variants.

In individuals infected with the Delta variant, no differences were identified in the viral load indicator between unvaccinated and partially vaccinated individuals. This suggests an equivalent level of transmissibility.

The study, which analysed 2,097 cases of laboratory-confirmed SARS-CoV-2 infection by RT-PCR, contributed to strengthening the scientific evidence on the lower effectiveness of mRNA vaccines against Delta-variant infection, as well as the greater transmissibility of this variant.

“The vaccines are an important tool to manage the pandemic but not the only one,” said Carlos de Sousa, Head of Molecular Biology at Unilabs Portugal. “The Delta variant poses new threats and is seriously changing the course of the pandemic. Continued testing, and the ability to identify new variants and their effects is crucial for decisions on additional measures and possible updates to the vaccines. The paper, which is currently under review by Emerging Infectious Diseases – an open access, peer-reviewed journal published by the CDC – emphasises that the Delta variant significantly changes the impact of the current vaccines, which were designed against the initial version of the virus. Right from the beginning, we at Unilabs embraced our role in helping the authorities understand the pandemic. Our findings are an important source of data – hey help generate insights into what is happening and they help anticipate future scenarios. This approach, together with our role in providing testing capacity, is key to our partnership with national health authorities.”

Welcome to the Unilabs website

Continue to the main corporate website

Or: Select a Unilabs country website from the list below