"Antibodies are a good clue, but they are not the only answer" says researcher and immunologist Helena Soares, leader of the Immunology and Pathogenesis lab from CEDOC - NOVA Medical School. This interview is part of a full scope report from Público newspaper, in which Helena joins other immunology experts from Instituto de Medicina Molecular (IMM), Universidade de Coimbra and Instituto Gulbenkian de Ciência (IGC), to comment on the public discussion regarding the need of a booster dose of the Covid-19 vaccine.
Helena also says that "it is normal for there to be a drop in antibody levels and this is true for all diseases and all vaccines, maximum levels do not hold indefinitely" and that "at this point, we still don't know what level (of antibodies) is needed to provide protection, but studies indicate that 8 months after vaccination there are still protective antibodies circulating" . Her team is precisely following a group of health professionals from the Hospital Professor Doutor Fernando Fonseca, Amadora, who were vaccinated in January. So far, in this sample of over 80 people, it has been seen that there is a spike in antibodies that is maintained at three months after inoculation. This translational project has been set up in collaboration with José Alves, head of the Immune Response and Vascular Disease lab at CEDOC, and director of the Systemic Immune-mediated Diseases Unit at Hospital Professor Doutor Fernando Fonseca.
But the experts warn that it's more important to know if immunity is maintained in terms of B cells and T cells, that also compose the memory cells that allow adaptive immunity in case of subsequent contacts withs SARS-CoV-2. “To identify B lymphocytes we need at least a day or a day and a half for the entire experiment”, she says. "It's also a more difficult test to automate. All of this makes it more difficult to do in a clinical analysis laboratory and they are mainly done in scientific research laboratories".
Helena also adverts that "it seems a little early, globally, for a third dose”. Although "it is known that the immune response in the elderly is weaker than in other adult population, but we have to follow the immune response of vaccinated people".