The study conducted by the Directorate General for Health (DGS) and the National Institute of Health Doctor Ricardo Jorge (INSA), with the collaboration of the Shared Services of the Ministry of Health (SPMS), the Central Administration of the Health System (ACSS), Unilabs laboratories, the Portuguese Red Cross and the Algarve Biomedical Centre, concluded that patients infected with the Ómicron variant spend on average four days less hospitalised than those infected with the Delta variant.
"It is also important to highlight that those infected with Omicron (BA.1) had a shorter hospital stay than those infected with Delta (B.1.617.2), an average difference of -4.0 days," states the epidemiological study on the Covid-19 pandemic, which was carried out in a similar way to similar agencies from Ministries of Health in other European Union countries.
The document states that cases of the Omicron variant showed a 75 percent reduction in risk of hospitalisation compared to the Delta variant.
According to the DGS and INSA study, for every 100 people hospitalised who were infected with the Delta variant, only 25 would be hospitalised if they had been infected with the Omicron variant, regardless of age, gender, vaccination status and whether they had a previous infection.
The study also reports that patients infected with the Delta variant stayed, on average, 8.6 days in hospital, while with Omicron that time drops to 3.7 days.
"This has important implications for the management of hospital services and will reduce the impact of the waves of Omicron on health systems," DGS and INSA stress.
The study also shows that people infected with Omicron have, on average, a lower risk of dying, "representing a reduction in the risk of death of 86 percent when infected with Omicron compared to Delta".
The study was conducted between 1 and 29 December 2021 when 164 hospitalisations due to the Delta variant and 16 due to the Ómicron variant of SARS-CoV-2 were recorded in Portugal.
During this period there were 26 deaths of people infected with Delta, but no hospitalisations in intensive care or deaths due to Omicron.
DGS and INSA said in a statement that the study showed "encouraging results that support the findings of similar studies conducted in other countries".
"However, Omicron is associated with a greater ability to partially escape the protection of the full vaccination scheme and a high transmissibility, translated into a higher absolute number of cases, so that even with reduced severity, there may be risk of overloading the health system," refer to the two entities.