Researchers today ruled that the future Covid vaccines must target a different type of virus.
Research suggests that the ability to identify which proteins pathogens use for replication could be a way to stop coronaviruses from spreading.
This same method may eliminate SARS-Cov-2 even before it becomes a problem, which makes jabs more efficient.
Experts fear that another virus of the same family, Covid, could cause the next pandemic.
This is a result of a four-month study that involved more than 700 health care workers.
Ten percent of people who tested positive for the virus had T-cells against its replication proteins.
These findings suggested that being infected by other coronaviruses (such as those that cause common cold) could provide some protection.
The current crop of vaccines — made by firms such as Pfizer and AstraZeneca — mainly target the spike protein on the outside of the virus.
The body then produces antibodies against the virus, and also activates T cells.
They are highly effective in preventing death and severe illnesses, according to real-world data and scientific tests.
Researchers believe that focusing on the proteins pathogens use to reproduce in vaccines in the future could help stop other coronaviruses. Jabs could be even more effective if this approach is used to eliminate SARS Cov-2.
The graph shows the viral load (left), antibody response (grey line) and T cell response (blue line to Covid infection. It shows that antibody levels drop faster, within months, while T cell levels — specifically the CD4+ and CD8+ T cells — can remain high for years
Targeting the protein Covid uses to spread in the body — found in every coronavirus — could stop people from becoming infected and transmitting the virus.
The study, by doctors at St Bartholomew’s Hospital, was carried out during the first wave of the virus last spring.
Seventy-eight percent of those tested for the virus were negative by PCR or antibody testing within the four month period.
The researchers were interested in finding out if this group was ever exposed to the virus and if it had been an “abortive” infection.
This is when cells become infected with a virus but do not replicate.
A sample of blood from 573 of the participants that did not show positive result showed around one-tenth of those tested had more than one of each type of T cell, CD4+ orCD8+.
Once the virus is inside, the T cells detect it and target the replication proteins of Covid to help rid the infection.
The proteins form part of a mechanism called the replication transcription complex (RTC) — they are the first sign of infection that the T cells can sport.
The NHS workers did not avoid infection entirely, but they were exposed to a low-level, abortive infection which could not be detected by testing.
Analysis showed the body also makes these T cells in response to other members of the coronavirus family — such as those that cause common colds every year — because they have a near-identical replication system.
It is possible because replication plays an essential role in the viral life cycle and is therefore less susceptible to mutation.
Dr Leo Swadling stated that the previous common cold may have provided these people with an advantage against the virus. This could tip the scales in favor of the immune system eliminating it before it can replicate.
And while millions of people are getting the common flu every year, over 9 million Britons have become infected since the beginning of the pandemic. Additionally, more than 140,000 Covid deaths have been documented, indicating that the vaccine is inadequate to protect against this deadly disease.
Researchers believe that a vaccine against the RTC could be used to combat all coronaviruses.
Currently, there are no vaccines that target replication proteins.
Leo Swadling, the lead author of the study (left), said that previous common cold exposure could have helped these people to protect themselves against the virus. This may have tipped the scales in favor of the immune system eliminating it before it can replicate. And Professor Mala Maini, a viral immunologist at UCL and senior study author, said the existing Covid vaccines are valuable, but ‘could do better’ at protecting against infection and new variants, as well as offering longer-lasting protection
Swadling stated that he hopes Dr. Swadling’s findings will prompt other vaccine manufacturers to focus on RtC.
He said the T cell response is longer-lasting than an antibody response, so next generation vaccines could provide more durable protection — ‘potentially blocking infection and transmission’.
Professor Mala Maini is a senior author of the study and a UCL viral immunologist.
However, she said that they could be better in protecting against infections and new types of bacteria as well as providing longer-lasting protection.
Dr Alexander Edwards, an associate professor in Biomedical Technology at the University of Reading who was not involved in the study, said T cells ‘can “sniff out” coronavirus proteins even when buried within the virus particle, in contrast to antibodies that “grab hold” of shapes on the surface’.
He stated that the study’s findings could have a significant impact on designing a new type of vaccine.
Current vaccines are ‘very effective at inhibiting viral growth and give excellent protection against severe Covid’, Dr Edwards said.
But their ‘tight focus’ on the spike protein — which vary between coronaviruses — means they only protect against one type of the virus, he said.
‘A vaccine that primes T cell immunity against different viral protein targets that are shared between many different coronaviruses would complement our spike vaccines that induce neutralising antibodies,’ Dr Edwards added.