In a recent study, scientists have discovered novel immune responses that may explain why some individuals never contracted COVID-19 despite exposure to the virus.
This groundbreaking study was conducted by a consortium of researchers from the Wellcome Sanger Institute, University College London (UCL), Imperial College London, and the Netherlands Cancer Institute.
The findings, published in the journal Nature, offer a comprehensive timeline of how the body responds to SARS-CoV-2, the virus responsible for COVID-19.
A healthcare worker places a test swab into solution for a PCR Covid-19 test at a Reliant Health Services testing site in Hawthorne, California on January 18, 2022. Photo by PATRICK T. FALLON/AFP via Getty Images
How Some People Never Contracted COVID-19
The study was part of the world's first COVID-19 human challenge study, where 36 healthy adult volunteers without any prior history of COVID-19 were deliberately exposed to the virus.
This was done under strict ethical guidelines and medical supervision. Using advanced single-cell sequencing techniques, researchers were able to analyze immune responses in unprecedented detail.
A key finding was that not all exposed participants developed COVID-19, allowing the identification of unique immune responses that seemed to prevent infection. Dr. Rik Lindeboom, co-first author, noted, "This was an unparalleled opportunity to observe immune responses upon encountering a new pathogen in adults without prior COVID-19 exposure."
The study revealed that individuals who did not develop a sustained infection exhibited specific, subtle immune responses. Notably, these individuals showed a high level of activity in a gene called HLA-DQA2 before exposure to the virus.
This gene appeared to play a crucial role in preventing the virus from establishing a prolonged infection. In contrast, those who developed a sustained infection had a rapid immune response in their blood but a slower response in the nasal passages, allowing the virus to establish itself there.
In simple terms, the study provided a clearer picture of how human cells respond in the early stages of COVID infection.
Dr. Marko Nikolić, the senior author of the study at UCL, highlighted the importance of these findings, as they provide new insights into the early events that determine whether the virus takes hold or is cleared before symptoms appear.
"We now have a much greater understanding of the full range of immune responses, which could provide a basis for developing potential treatments and vaccines that mimic these natural protective responses," Dr. Nikolić said.
The researchers also identified common patterns among activated T-cell receptors, which recognize and bind to virus-infected cells. This insight offers the potential for developing targeted T-cell therapies against COVID-19 and other diseases.
This study's insights into the body's early immune responses are crucial for developing better treatments and preventive measures for COVID-19. The detailed dataset generated by the researchers provides a valuable reference for understanding how a normal immune response to a new pathogen compares to a vaccine-induced response.
As of June 2023, over 760 million COVID-19 cases and 6.9 million deaths have been recorded worldwide.
