Immunity to SARS- COV-2 fades quickly after infection as confirmed in medical experiment conducted in 1970’s by two independent teams. Within one or two weeks of infection, a type of antibody called IgM (Immunoglobulin M) appears which mobilize against the virus and gradually starts disappearing even after the infection persist.
After infection has been cleared i.e., within two or three weeks IgG (Immunoglobulin G) antibodies will appear and in many cases, once IgG has appeared will stay for many years within the person a long term immunity against the disease. But SARS-COV-2 IgG antibodies from recovered covid-19 patients decline rapidly. Even in some convalescent covid-19 patients both IgG and IgM are absent.
This disappearance of antibodies may be due to evolving of the corona virus proteins to become as weak immunostimulants or it may have manipulated the human immune response to its own advantage. It is already known that SARS-COV-2 produces more than one protein that actively interfere with host immune function.
Orf-3b (Open Reading Frame -3b) gene product decides in starting or stopping the production of antiviral antibodies and T- Cells. Generally it’s product (protein) down-regulates the production of INF ¥ ( Interferon gamma) and IL-2 (Interleukin) thereby stopping the initiation of antiviral antibodies and T-Cells.
SARS-COV-2 also has similar Orf-3b gene type complement system that shows features of infection like
- Antibody negative convalescents
- Rapidly fading antibody levels
- Re-infection
SARS- COV antibodies peaked at 4 months and persisted for two years in patients who recovered from SARS.
MERS- COV antibodies waned within first six months of illness
SARS-COV-2 antibodies disappeared in a convalescent COV-19 patients within three months. The neutralizing antibodies of SARS- COV -2 and specific antibodies are short lived and does not neutralize the infection. These potent neutralizing antibodies can be identified by high – throughput single – cell RNA and VDJ ( Variability Diversity and Joining) sequencing of antigen-enriched B cells from convalescent patients.
