People recovered from COVID get immunity for 8 months, vaccines may extend duration: Study

According to a new study published in the journal Science Immunology, conducted by Australian scientists from Monash Univeristy, it was revealed that people who have recovered from the novel coronavirus infection have an immune memory to protect themselves from the reinfection for as long as 8 months. The study said that there are specific cells in the immune system, called the ‘B’ cells, which when re-exposed to the virus, leads to a protective immune response through rapid production of protective antibodies. 25 COVID-19 patients participated in the study. Also, 36 blood samples were taken from them, beginning from Day 4 of the infection to day 242.

Immunity for 8 months 

It was then concluded that antibodies against the virus started to come off after 20 days of infection. However, this is when memory B cells work as they remember few characteristics of the virus. Using which, the spike protein helps the virus enter host cells. “The antigen-specific B cell response to SARS-CoV-2 was characterized using recombinant forms of the RBD and NCP. Both proteins were generated in Expi293F cells with an AviTag for targeted biotinylation and tetramerization with fluorescently-labeled streptavidins to minimize epitope masking”, said the study. 

Read: COVID-19: Switzerland Approves Pfizer Vaccines, 90 Year Old Woman First To Get Shot

(Construct design and detection of SARS-CoV-2 RBD- and NCP-specific B cells. (A) Recombinant spike receptor binding domain (RBD) and nucleocapsid protein (NCP) constructs of SARS-CoV-2. (B) SDS PAGE of purified, reduced (R) or non-reduced (NR) recombinant RBD and NCP. (C) Flow cytometry stainings of CD19+ B cells from an uninfected control and a recovered COVID-19 patient using double discrimination through inclusion of two fluorescent tetramers for each protein (RBD or NCP) in the same staining tube. Image Credits: immunologysciencemag.org)

(Neutralizing antibodies and RBD-, and NCP- and HA-specific IgG antibody levels. Credits: immunologysciencemag.org)

( RBD- and NCP-specific Bmem cells predominantly express IgM or IgG1. Image Credits: immunologysciencemag.org)

( Composition and kinetics of SARS-CoV-2 RBD- and NCP-specific Bmem in convalescence. Relative composition of the Bmem cell compartment based on Ig isotype and IgG subclass expression within (A) RBD-specific (RBD+) and (B) NCP-specific (NCP+) Bmem subsets. Patients’ data are ordered by days post-symptom onset. Absolute numbers of total, IgM+and IgG+ Bmem cells specific for (C) RBD+ or (D) NCP+. Image Credits: Immunology.science.org)

Read: COVID-19: Dubai To Begin Inoculation With Pfizer-BioNTech Vaccine From Dec 23

Study co-author, Menno van Zelm, from the Monash University Department of Immunology and Pathology, said, “These results are important because they show, definitively, that patients infected with the COVID-19 virus do in fact retain immunity against the virus and the disease. This has been a black cloud hanging over the potential protection that could be provided by any COVID-19 vaccine and gives real hope that, once a vaccine or vaccines are developed, they will provide long-term protection”. It was concluded that these virus-specific memory B cells were present for a period of eight months after infection.

Read: COVID-19: Pfizer Nears Deal With Trump Admin, Will Ship 100 Mn Additional Vaccine Doses

Also Read: Russia Cuts Size Of COVID-19 Vaccine Study, Stops Enrollment

(Image Credits: Pixabay)