The Times
Tom Whipple
Gerry Gajadharsingh writes:
“I have written about T cells before and in my recent articles regarding the new spike protein antibodies one of the pieces of the jigsaw that we still await is a proper validated commercial T-cell test. The good news that this is taking place in research environments and the research below suggest that T-cell responses in those vaccinated or previously infected with coronavirus were largely unaffected by each of the new key variance of the virus, this was expected but it’s great to have it confirmed by some research.
Whilst the vaccine will play an important part in providing what we call an acquired immune response hopefully in many people (infection or vaccination is priming are immune systems hence the term acquired), individuals still have a part to play in reducing their risk profile as much as they can in particular obesity which stands out to be a major risk factor in developing severe COVID-19. I’ve also previously written at the strategies we can take as individuals to boost our own innate immune system which supports this T-cell response.”
A crucial wing of the immune system appears to be just as good at recognising all the new coronavirus variants, a study has found.
In laboratory tests, T-cell responses in those vaccinated or previously infected with coronavirus were largely unaffected by each of the key variants. This included the new Brazilian variant, found in small numbers in the UK last week.
The new findings suggest that even if people are able to be reinfected by the variants, some of which are believed to partially evade our first immune response, the body will have key tools for preventing severe disease.
However, the scientists behind the findings cautioned that the protective abilities of the T-cell response remained to be proven in the field.
“If you have a good T-cell response you may not be able to prevent infection, but you should be able to soften the blow,” Professor Alessandro Sette, from the La Jolla Institute for Immunology in San Diego, California, said. “That is important. The opposite scenario would have been really concerning, if the new variants had been able to evade both the antibody response and the T-cell response.”
After infection or vaccination, people produce antibodies specific to the coronavirus. These recognise and latch on to part of the spike the virus uses to infect cells — effectively blocking it.
“Basically, you create a wall and the virus bounces off that wall,” Sette said. “This is sterilising immunity.”
One of the concerns about new variants, particularly those from South Africa and Brazil, is they contain a mutation that changes the shape of the spike, meaning they evade antibodies built up against the old version.
However, that is only the first line of defence. We know from vaccine trials that even if people do become infected following vaccination, they are still at least 50 per cent less likely to develop severe disease compared with those who were infected without being vaccinated.
The second line of defence that helps them to fight off Covid comes in part from T-cells, which are harder to trick.
“One of the things that T-cells do is kill infected cells or create an antiviral response,” Sette said. “So, if you have T-cells you may not prevent the infection, but you may lessen the severity of the disease. You may also shorten the duration of a disease.”
Unlike antibodies, these T-cells home in on a larger portion of the virus’s spike, meaning it has to change more significantly to elude them.
Because each person’s T-cells choose these larger sections of viral proteins at random, it also means it’s harder for the virus to evolve in a way that it evades them at a population level. Even if it finds a way to trick one person, that does not mean it will trick the person they infect.
Sette’s research, which has been published before being peer reviewed, used blood taken from people who had received the Moderna or Pfizer vaccines or been naturally infected. It showed that while their antibody response might be reduced, their T-cell response held up well.
“Putting two and two together you would imagine that if you have a good T-cell response you would be able to lessen symptoms.”
The findings will be comforting for Britain’s vaccine strategy. However, public health officials cautioned that it was still important to prevent the spread of new variants. No protection is perfect and any vaccine that can infect people better — even only mildly — will risk slowly the raising of lockdown.
Sette said that it would also be key to see what happens in the real world. Some cities in South America that are believed to have had high infection levels are seeing a second spike in hospital admission numbers, apparently caused by the new Brazilian variant.
This includes places like Leticia in Colombia, where studies suggest that about 60 per cent of the population were previously infected with the old variant. This at least suggests that some people are being reinfected and ending up in hospital.