The recent findings published in the journal Science, based on blood sample analysis of 188 patients, show that Covid-19 survivors could potentially have immunity against the virus for months or even years. This article explores these findings in detail.
Background
Ever since the outbreak of the Covid-19 pandemic, numerous studies have been conducted to ascertain the duration of immunity post-recovery. Diverse results have been obtained from different studies. A study published in July 2020 suggested that immunity might fade within months, making the individual susceptible to re-infections.
New Study Findings
A more recent study indicates a longer-lasting immunity against the novel coronavirus. It noted that the immune response to the virus could last at least eight months after the onset of symptoms from the initial infection. The study also suggests that almost all Covid-19 survivors house immune cells capable of defending against re-infection.
This latest research measures not just antibodies, but also memory B cells, helper T cells, and killer T cells simultaneously. This study also addresses concerns raised by other Covid-19 data that showed a steep decrease of Covid-specific antibodies over time.
Understanding Immunity
Immunity refers to the body’s capability to defend itself against disease-causing organisms. It is broadly classified into two categories: Innate immunity and Acquired immunity. Innate immunity, a non-specific type of defense, is present from birth. Acquired immunity, however, is pathogen specific and characterized by memory.
Upon its first encounter with a pathogen, the body produces a low-intensity primary response. Consequent encounters with the same pathogen induce a more intense secondary or anamnestic response. This heightened reaction is due to the body’s “memory” of the first encounter.
Understanding Antibodies
An antibody, also known as an immunoglobulin, is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses.
Significance of T cells and B cells
T cells (thymus cells) and B cells (bone marrow-or bursa-derived cells) are crucial cellular components of the adaptive immune response. T cells contribute to cell-mediated immunity, while B cells are primarily responsible for humoral immunity, which relates to antibodies.
Role of Memory B cells (MBCs)
Memory B cells, a subtype of B cells formed within germinal centers following primary infection, can survive for decades and quickly generate a robust antibody-mediated immune response in case of re-infection, also known as a secondary immune response.
Importance of Helper T cells
Helper T cells play a key role in adaptive immunity as they are necessary for almost all adaptive immune responses. They help activate not only B cells that secrete antibodies and macrophages that destroy ingested microbes, but also killer T cells that exterminate infected target cells.
Function of Killer T cells
Killer T cells, a type of T lymphocyte, are responsible for eliminating cancer cells, cells infected with viruses, or any cells damaged in other ways.
