LISBON - A new study by the Joao Lobo Antunes Institute of Molecular Medicine (IMM) here proved that antibodies against SARS-CoV-2 virus, the virus responsible for COVID-19, are detected up to seven months after infection in 90 percent of patients.

The results, now published in the European Journal of Immunology, also show that the levels of antibodies produced are determined by the severity of the disease, and not by the age of the infected person.

The study started at the beginning of the pandemic in Portugal in March 2020, when researchers set up a sensitive, specific and versatile serology test for COVID-19.

Working with doctors at the Hospital Center Lisboa Norte, the team began to monitor the antibody levels of 300 patients and healthcare professionals and more than 200 volunteers who were followed after contracting COVID-19.

"The results of this study over six months show a classic pattern of immune response until the 7th month after infection, with a rapid increase in antibody levels in the first three weeks after symptoms and a subsequent reduction", explained Marc Veldhoen, lead investigator of the project.

"In the initial response phase, our results show that on average men produce more antibodies than women, but the levels are balanced during the resolution phase and are similar between the sexes in the months after SARS-CoV-2 infection", he added.

Collaborating with the Portuguese Institute for Blood and Transplantation (IPST), Veldhoen confirmed "a robust activity until the seventh month after infection in a large proportion of previously tested individuals."

"The coming months will be essential to assess the robustness of the immune response to SARS-CoV-2 infection and to find clues to some open questions, such as the duration of this immune response or whether there is a possibility of reinfection", concluded the IMM researcher.

Data from the World Health Organization indicated that as of Oct 2, there were 193 COVID-19 candidate vaccines being developed worldwide, of which 42 were in clinical trials amid a global fight against the pandemic.