The vaccine being developed by the University of Oxford (United Kingdom) and the company AstraZeneca against SARS-CoV-2, the virus that generates COVID-19, has shown similar safety and immunogenicity results in healthy older adults (56 years or older) to those observed in adults aged 18 to 55, according to a preliminary analysis published in the reputed scientific journal The Lancet.
In this phase 2 trial, the vaccine has been found to cause few side effects and induces immune responses in both parts of the immune system in all age groups and at low and standard doses, eliciting a T-cell response within 14 days of the first dose of the vaccine (i.e., an immune response cell, which could find and attack cells infected with the virus), and an antibody response within 28 days of the booster dose of the vaccine (i.e., a humoral immune response, which could find and attack to the virus when it is circulating in the blood or lymphatic system).
Now, phase 3 trials are underway to confirm these results, as well as the efficacy of the vaccine in protecting against SARS-CoV-2 infection, in a wider range of people, including older adults with underlying health problems.
“Immune responses to vaccines tend to decline in older adults because the immune system gradually deteriorates with age, which also makes older adults more susceptible to infections. Therefore, it is crucial that COVID-19 vaccines be tested in this group which is also a priority group for immunization, “explains the study’s lead author, Professor Andrew Pollard, from the University of Oxford.
Adverse reactions to the vaccine were mild (the most common effects were pain and tenderness at the injection site, fatigue, headache, fever, and muscle pain). Adverse effects were less common in older adults than in younger ones.
T-cell responses against the SARS-CoV-2 spike protein peaked 14 days after the first vaccination, regardless of age and standard or low dose of the vaccine.
The authors point out some limitations of your study, among them that participants in the oldest age group had a mean age of 73-74 years and few underlying health problems, so they may not be representative of the general elderly population, including people living in centers residential care or are over 80 years old.
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