Ruminations: COVID and Cold ... Kissing Cousins?

"We found that high levels of pre-existing T cells, created by the body when infected with other human coronaviruses like the common cold, can protect against COVID-19 infection."
"Being exposed to the SARS-CoV-2 virus doesn’t always result in infection, and we’ve been keen to understand why. We found that high levels of pre-existing T cells, created by the body when infected with other human coronaviruses like the common cold, can protect against COVID-19 infection."
"While this is an important discovery, it is only one form of protection, and I would stress that no one should rely on this alone. Instead, the best way to protect yourself against COVID-19 is to be fully vaccinated, including getting your booster dose."
Dr.Rhia Kundu, researcher, National Heart & Lung Institute, Imperial College London

"In contrast, the internal proteins targeted by the protective T cells we identified mutate much less [thus less likely to diminish efficacy of vaccines]."
"Our study provides the clearest evidence to date that T cells induced by common cold coronaviruses play a protective role against SARS-CoV-2 infection. These T cells provide protection by attacking proteins within the virus, rather than the spike protein on its surface."
"The spike protein is under intense immune pressure from vaccine-induced antibody which drives evolution of vaccine escape mutants. In contrast, the internal proteins targeted by the protective T cells we identified mutate much less. Consequently, they are highly conserved between the various SARS-CoV-2 variants, including omicron."

"New vaccines that include these conserved, internal proteins would therefore induce broadly protective T cell responses that should protect against current and future SARS-CoV-2 variants."
Professor Ajit Lalvani, study co-author, Director of the NIHR Respiratory Infections Health Protection Research Unit, Imperial College


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According to a newly published study, high levels of T cells from common cold coronaviruses can provide protection against COVID-19. A finding which may lead to new approaches to target for infection avoidance for second-generation vaccines. While evidence exists of waning antibody levels six months following inoculation, T cells also are believed to play a pivotal role in providing protection.

Initiated in September of 2020, the study looked at cross-reactive T-cell levels generated through previous common colds in 52 household contacts of positive COVID-19 cases emerging soon after exposure to the cold virus, in an effort to determine whether those who were exposed went on to develop infection.

Of the 26 contacts who failed to develop infection, significantly higher levels of T cells wee seen to be present, in comparison to people who were infected. The study did not mention how long T cell protection might last. The study was published in Nature Communications, concluding that the internal proteins of the SARS-CoV-2 virus targeted by the T cells may realize an alternate target for producers of vaccines.

COVID-19 vaccines now in circulation target the spike protein which mutates regularly, in so doing creating variants such as Delta and Omicron, diminishing the efficacy of vaccines against symptomatic infection. "In contrast, the internal proteins targeted by the protective T cells we identified mutate much less", observed Professor Ajit Lalvani.