Common cold may protect against SARS-CoV-2 infection and lead the way…

The common cold can have some protective benefits against coronavirus infection. Camilo Fuentes Beals / EyeEm / Getty Images
  • Some people are less susceptible to SARS-CoV-2 infection.
  • A new study suggests that T cells from previous coronavirus infection, such as the common cold, may protect against SARS-CoV-2.
  • These T cells target the internal SARS-CoV-2 proteins.
  • T-cell-stimulating vaccines are likely to provide longer-term protection against SARS-CoV-2 and protect against new variants.

One of the mysteries of COVID-19 is why some people appear to be resistant to infection despite exposure to SARS-CoV-2. Scientists from Imperial College London have published a study suggesting that immune cells formed in response to a cold may protect against SARS-CoV-2 infection.

When you catch a cold, your immune system produces antibodies and T cells. These T cells (also called memory T cells) survive much longer than antibodies and help prevent a person from catching a cold again.

Coronaviruses cause around 15-30% of colds. This new study suggests that pre-existing T cells from these previous coronavirus colds may protect against SARS-CoV-2 infection.

Observational study, published in communications in nature, held in the United Kingdom, starting in September 2020. Researchers recruited 52 people who lived with someone who had PCR-confirmed SARS-CoV-2. All participants performed a PCR test on days 1, 4, and 7 of the study.

The study was conducted before any vaccine against COVID-19 was approved.

Some resisted the infection

Half of the participants subsequently tested positive for SARS-CoV-2. The remaining 26 were not infected with the virus.

The researchers did not notice any differences between the two groups. Dr. Rhia Kundu of the Imperial National Heart and Lung Institute and the first author of the study, spoke to Micro B Life. She said: “We looked at age, biological sex and BMI and there was no difference between our household contacts who were PCR positive and those who remained PCR negative. […]

“Crucially, we also looked at the relationship to the index case (i.e., whether there were partners, a child, and a parent or roommate who would have limited exposure) and noticed no difference between PCR + and PCR contacts. This suggests that the exposure was similar between the two groups. ”

All participants provided blood samples between days 1 and 6 of the study. The researchers analyzed those blood samples for T cell levels from previous coronavirus infections.

High number of T cells

The researchers found that those who did not have SARS-CoV-2 had significantly higher levels cross-reactive T cells in their blood. These memory T cells target proteins within the SARS-CoV-2 virus.

Talking to MBL, Dr. Arturo Casadevall, a respected Bloomberg professor and chairman of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, commented: “The study is small, but the findings are interesting and may be affected and COVID-19. ”

He added: “This study reinforces the idea that an individual’s immune history, and especially previous infection with other coronaviruses, is a major factor in determining who will become ill.”

Direction for new vaccines

Current vaccines target spike proteins (antigens) to SARS-CoV-2 and stimulate the production of spike protein-specific antibodies. Cross-reactive T cells target internal proteins in the virus.

Spiky antigens on the surface of the virus often mutate, leading to new variants. Researchers suggest that second-generation vaccines should include vaccines against class antigens, along with spiked vaccines. A vaccine that stimulates T cell production is likely to provide longer-lasting immunity than one that stimulates antibody production alone.

“By developing vaccines that target parts of the virus that cannot be so easily changed (its internal machinery that needs to be replicated), we could better protect an individual’s immune system against new variants. The AT cell vaccine could be the next step in a vaccination strategy to control SARS-CoV-2. ”

–Dr. Rhia Kundu.

Dr. Casadevall supported her view: “It may be possible to make very different types of vaccines from those we currently use to protect against COVID-19 by inducing cellular immunity. ”

The Imperial research team is now collaborating with other research groups on the development and testing of second-generation vaccines.

Do not rely on immunity to the cold

Dr. Simon Clarke, associate professor of cell microbiology at the University of Reading in the UK, told the Science Media Center: “It could be a big mistake to think that anyone who has recently caught a cold is protected from Covid-19, as coronaviruses make up only 10-15% Cold.”

Dr. Kundu reiterated this message: “Cold does not necessarily mean you have these T cells, and vaccination remains the best possible protection against SARS-CoV-2 infection and spread.”

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