Why post-recovery Covid-19 immunity doesn’t last

Prashasti Awasthi | Updated on August 21, 2020

High levels of cytokines to blame, says study

High levels of cytokines — a broad and loose category of small proteins important in cell signalling — associated with coronavirus could prevent long-term response of antibodies, according to a study published in the journal Cell on August 19.

The researchers believe that this is the reason why coronavirus immunity cannot last long after the recovery.

Co-senior author Dr Shiv Pillai, professor at Harvard Medical School, MIT, and a member of the Ragon Institute of Massachusetts General Hospital, said in a statement: “We’ve seen a lot of studies suggesting that immunity to Covid-19 is not durable because the antibodies decline over time. This study provides a mechanism that explains this lower-quality immune response.”

The study was carried out in convalescent Covid-19 patients. It indicated that humoral immunity is often short-lived, and most SARS-CoV-2 antibodies exhibit limited somatic hypermutation — adaptation to new foreign elements.

The scientists noted that the life-long memory of a pathogen allows the body to quickly and effectively identify and attack pathogens in the case of reinfection. This is achieved by the formation of T follicular helper cells found in the secondary lymphoid organs.

However, in the case of SARS-CoV-2, due to the evasion of antiviral aspects of innate immunity, T follicular helper cells get blocked.

The authors suggested that possibly cytokines in Covid-19 lymph nodes block the final step in T follicular helper cell differentiation, which is required for the formation of germinal centres.

Vaccine-induced immunity

“Without the formation of germinal centres, there is unlikely to be long-term memory to this virus developing from natural infections, meaning that while antibodies may protect people for a relatively short time, a single person who recovers from the disease could get infected again, perhaps six months later, or even multiple times with SARS-CoV-2,” added Pillai. “This suggests that developing herd immunity may be difficult,” he speculated.

The study mentioned that developing herd immunity may be difficult in the case of Covid-19 due to impaired infection-induced protective immunity and low durability antibody responses.The authors noted that their findings should not affect vaccine-induced immunity, as vaccines do not induce cytokine storms.

Published on August 21, 2020

Follow us on Telegram, Facebook, Twitter, Instagram, YouTube and Linkedin. You can also download our Android App or IOS App.

This article is closed for comments.
Please Email the Editor

You May Also Like