AR
UR
Research suggests that catching a common cold could significantly help the body in fighting COVID-19. This will further pave the way for a universal vaccine that will offer necessary protection against the bigger Coronavirus family.
The scientific world has underlined the human body's ability to boost its immune response against the virus, whether through infection or vaccination, can help in the ongoing efforts to ensure recovery from the pandemic.
An abortive infection in which a person is exposed to the virus but does not have enough elements in the system to test positive can also impact the immune system despite Sars-CoV-2, the virus that causes COVID-19, being gradually wiped off from the body.
Evidence have also come to light showing that previous exposure to other coronaviruses, including cold, can give relevant protection to the immune system during infection with Sars-CoV-2.
Why can brief infections boost protection?
It has been known that several COVID-19 infections are asymptomatic, adding that the Omicron variant has a higher rate of such cases than other common variants.
In such cases, a person may have no symptoms but will test positive during a PCR test (which looks for viral genetic material) or a lateral flow test (which looks for viral antigens, which are types of proteins).
While abortive infections are a separate category due to exposure to the virus, it has never developed enough to be detected by PCR or lateral flow tests.
According to Dr Andrew Freedman, an infectious diseases expert at Cardiff University in the UK, such abortive infections are theoretically strengthening the immunity of individuals.
“If they have good T cell immunity, although they’re getting exposed, they’re not developing a full-blown infection,” he said.
Notably, T cells are immune system cells that help other immune system cell such as B cells to produce antibodies. T cells also have the potential to destroy human cells that are infected with a pathogen and are often linked with long-lasting immunity.
Professor Paul Hunter, an infectious diseases specialist and professor in medicine at the University of East Anglia in the UK, has also noted that the idea behind abortive infections strengthening immune protection against Sars-CoV-2 was “plausible”. However, it was yet to be proven.
On the other hand, mild infection, which does not have a substantial impact on effect on a person’s T-cell count, probably have “a small if any” impact on the person's immunity.
“We know with Covid, the more severely ill you get, the stronger the immunity after you’ve recovered, unless you die,” Prof Hunter said.
Could the common cold help fight off the virus?
According to Dr Freedman, the ability to fight off SARS-CoV-2 can enhance. Therefore, being infected with a coronavirus causing common cold can give a person protection against SARS-CoV-2.
“Previous coronaviruses may provide some protection,” Dr Freedman said.
Dr Leo Swadling, who studies T cell immunity at University College London (UCL), has been studying the issue with colleagues, including Professor Mala Maini. Last month, Dr Swadling and Professor Maini along with other researchers published a paper that discussed how some people who may have had a brief exposure to Sars-CoV-2 recovered from the infection without testing positive or developing antibodies.
According to them, “pre-existing memory T cell responses” which developed from previous infections with other coronaviruses could be behind such abortive infections.
They analysed healthcare workers at St Bartholomew’s Hospital in London who tested negative for antibodies against COVID-19. During their research, they found individuals have T cells that recognise the first proteins a coronavirus makes after it enters a cell. It further makes up the virus’s replication-transcription complex (RTC). Researchers found T cells in blood taken in March 2020 as well as in a set of samples taken before the pandemic.
“These T cells likely came from previous exposure to endemic common colds coronavirus infections (Human coronaviruses, HCoV), although some pre-existing T cells also likely came from exposure to totally different infections,” Dr Swadling explained.
Will this facilitate the development of a universal coronavirus vaccine?
According to the studies, the pre-existing T cells target parts of the virus that are the same in HCoV and Sars-CoV-2. While conducting the lab tests, researchers found these pre-existing T cells as well as T cells generated by an abortive infection were able to recognise both Sars-CoV-2 and HCoV.
Furthermore, exposure to Sars-CoV-2 that led to an abortive infection resulted in increasing the numbers of the T cells. It also helped in the strengthening of a person’s immunity against the coronavirus.
However, Dr Swadling affirmed that it is still unclear if immunity is in fact strengthened by abortive infections.
“But we know from many Sars-CoV-2 studies that there is now a strong association between having an early Sars-CoV-2 T cell response and being protected from severe disease, and that these pre-existing T cells are recruited into early immune responses,” he added.
He concluded that T cells are crucial to protection from the disease.
Scientists are therefore looking at the possibility of developing vaccines that can provide protection against multiple coronaviruses.
SOURCE : The National News