- Some people are less susceptible to SARS-CoV-2 infection.
- A new study suggests that T cells from previous infection by other coronaviruses, such as the common cold, may protect against SARS-CoV-2.
- These T cells target internal proteins of SARS-CoV-2.
- Vaccines that stimulate T cells are likely to provide longer-lasting protection against SARS-CoV-2 and protect against new variants.
One of the mysteries of COVID-19 is why some people seem resistant to infection despite exposure to SARS-CoV-2. Scientists of Imperial College London have published
When you catch a cold, your immune system makes antibodies and T cells. These T cells (also called memory T cells) last much longer than antibodies and help prevent someone from catching the same cold again.
Coronaviruses cause about
The observational study, published in
The study took place before any COVID-19 vaccines were approved.
Half of the participants then tested positive for SARS-CoV-2. The other 26 have not contracted the virus.
The researchers noticed no differences between the two groups. dr. Rhia Kundu from Imperial’s National Heart and Lung Institute and lead author of the study, spoke to Medical News Today. She said: “We looked at age, biological sex and BMI, and there were no differences between our household contacts who were PCR positive and those who remained PCR negative. […]
“Critically, we also looked at the relationship with the index case (ie were partners, child and parent, or a housemate where limited exposure would have occurred) and saw no difference between PCR+ and PCR contacts. This suggests that exposure was similar between the two groups.”
All participants provided blood samples between days 1 and 6 of the study. The scientists analyzed these blood samples for levels of T cells from previous coronavirus infections.
The scientists found that those who did not contract SARS-CoV-2 had significantly higher levels of
Speak with MNT, dr. Arturo Casadeval, Bloomberg Distinguished Professor and Chair of Molecular Microbiology and Immunology at the Johns Hopkins Bloomberg School of Public Health, noted: “The study is small, but the findings are interesting and consistent with other data that demonstrates previous experience with other coronavirus infections a person’s susceptibility to COVID -19.”
He added: “This study reinforces the idea that a person’s immunological history, and in particular previous infection with other coronaviruses, is an important factor in determining who gets sick.”
Current vaccines target the spike proteins (antigens) on SARS-CoV-2 and stimulate the production of antibodies specific for the spike proteins. The cross-reactive T cells target internal proteins in the virus.
Spike antigens on the surface of the virus often mutate, creating new variants. The researchers suggest that second-generation vaccines should contain non-spike antigen vaccines along with spike antigens. A vaccine that stimulates the production of T cells is likely to provide longer lasting immunity than a vaccine that only stimulates the production of antibodies.
“By developing vaccines that target the parts of the virus it can’t change as easily (the internal machinery it needs to replicate), we can better future-proof an individual’s immune system against emerging variants. AT cell vaccine could be this next step in the vaccination strategy to control SARS-CoV-2.”
–Dr. Rhia Kundu.
dr. Casadevall supported her view: “It may be possible to create very different types of vaccines than the ones we currently use to protect against COVID-19 by triggering
Imperial’s research team is now working with other research groups to develop and test second-generation vaccines.
dr. Simon Clarke, Associate Professor in Cellular Microbiology, University of Reading in the UK, told the Science Media Center: “It could be a serious mistake to think that anyone who has recently caught a cold is protected from Covid-19, as coronaviruses are only 10 – 15% of colds.”
dr. Kundu echoed this message: “Having a cold does not necessarily mean you have these T cells, and vaccination remains the best possible protection against SARS-CoV-2 infection and spread.”
For live updates on the latest developments regarding the novel coronavirus and COVID-19, click here.