Cellular immunity to Covid-19 could last for up to six months after infection, a study has found.
Researchers evaluated 100 health care workers who suffered either asymptomatic or mild infections in March and April.
Tests six months later showed that while the antibody levels had dropped for some, their T-cell response, a type of white blood cell that attacks cells infected with the virus, remained robust.
The researchers said the results suggest T-cells could play a more important role than antibodies in combating the infection.
This bodes well for the long term, in terms of both vaccine development and the possibility of long-term protection against re-infection
"These results provide reassurance that, although the titre of antibody to Sars-CoV-2 can fall below detectable levels within a few months of infection, a degree of immunity to the virus may be maintained," said Charles Bangham, chair of immunology at Imperial College London.
Levels of T-cells were 50 per cent higher in those who experienced symptoms at the time of their infection.
The reasons for that are not yet clear, but the researchers said it could either mean people with more severe disease are left with better protection, or asymptomatic Covid-19 patients are able to fight the virus without generating a large immune response.
But experts caution it is still not clear how immunity to Covid-19 works.
"This bodes well for the long term, in terms of both vaccine development and the possibility of long-term protection against re-infection," said Eleanor Riley, an immunology and infectious disease professor at Edinburgh University.
She added, however, that "we don't yet know whether the people in this study are protected from re-infection."
The study, led by the UK coronavirus immunology consortium, has not yet been reviewed.
The immune system is complex, and involves multiple parts.
If the innate immune system does not halt an infection, B-cells and T-cells mount a defense against it. Some T-cells act as slayers against infected cells, while others stimulate B-cells to generate antibodies.
A recent large-scale study, also conducted by Imperial College London, added to mounting evidence suggesting antibodies to Covid-19 wane quickly, dropping by a quarter in three months.
At the time, researchers said the results could point to a decline in the immunity of the population, leading to a heightened risk of reinfection.
But the drop, which many experts have said is expected, would be much less of a concern if T-cells ultimately prove more important in combating a Covid-19 infection.
There have been a handful of cases of reinfection so far.
Of the four cases studied by researchers, symptoms were worse in two patients, suggesting no clear pattern.
But experts have said if SARS-Cov-2, which causes Covid-19, follows the same pattern as other coronaviruses, reinfections will become common.
Research has shown it is possible to catch a cold caused by the same strain months later as immunity fades quickly.
In one study from Kenya in 2018, almost 30 per cent of those who caught one variant of a coronavirus experienced a second reinfection. About 10 per cent caught it a third time and one person was infected four times.
A number of reinfections occurred only three months after the first bout, and in multiple cases the viral load actually increased, “revealing ineffective protective immune responses after initial exposure”.
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Muslim Council of Elders condemns terrorism on religious sites
The Muslim Council of Elders has strongly condemned the criminal attacks on religious sites in Britain.
It firmly rejected “acts of terrorism, which constitute a flagrant violation of the sanctity of houses of worship”.
“Attacking places of worship is a form of terrorism and extremism that threatens peace and stability within societies,” it said.
The council also warned against the rise of hate speech, racism, extremism and Islamophobia. It urged the international community to join efforts to promote tolerance and peaceful coexistence.
The Buckingham Murders
Starring: Kareena Kapoor Khan, Ash Tandon, Prabhleen Sandhu
Director: Hansal Mehta
Rating: 4 / 5
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Position: legal consultant with Al Rowaad Advocates and Legal Consultants.
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What are the main cyber security threats?
Cyber crime - This includes fraud, impersonation, scams and deepfake technology, tactics that are increasingly targeting infrastructure and exploiting human vulnerabilities.
Cyber terrorism - Social media platforms are used to spread radical ideologies, misinformation and disinformation, often with the aim of disrupting critical infrastructure such as power grids.
Cyber warfare - Shaped by geopolitical tension, hostile actors seek to infiltrate and compromise national infrastructure, using one country’s systems as a springboard to launch attacks on others.
FIXTURES
Monday, January 28
Iran v Japan, Hazza bin Zayed Stadium (6pm)
Tuesday, January 29
UAEv Qatar, Mohamed Bin Zayed Stadium (6pm)
Friday, February 1
Final, Zayed Sports City Stadium (6pm)
The Vile
Starring: Bdoor Mohammad, Jasem Alkharraz, Iman Tarik, Sarah Taibah
Director: Majid Al Ansari
Rating: 4/5
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How to watch Ireland v Pakistan in UAE
When: The one-off Test starts on Friday, May 11
What time: Each day’s play is scheduled to start at 2pm UAE time.
TV: The match will be broadcast on OSN Sports Cricket HD. Subscribers to the channel can also stream the action live on OSN Play.
F1 The Movie
Starring: Brad Pitt, Damson Idris, Kerry Condon, Javier Bardem
Director: Joseph Kosinski
Rating: 4/5
Watch live
The National will broadcast live from the IMF on Friday October 13 at 7pm UAE time (3pm GMT) as our Editor-in-Chief Mina Al-Oraibi moderates a panel on how technology can help growth in MENA.
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Some of Darwish's last words
"They see their tomorrows slipping out of their reach. And though it seems to them that everything outside this reality is heaven, yet they do not want to go to that heaven. They stay, because they are afflicted with hope." - Mahmoud Darwish, to attendees of the Palestine Festival of Literature, 2008
His life in brief: Born in a village near Galilee, he lived in exile for most of his life and started writing poetry after high school. He was arrested several times by Israel for what were deemed to be inciteful poems. Most of his work focused on the love and yearning for his homeland, and he was regarded the Palestinian poet of resistance. Over the course of his life, he published more than 30 poetry collections and books of prose, with his work translated into more than 20 languages. Many of his poems were set to music by Arab composers, most significantly Marcel Khalife. Darwish died on August 9, 2008 after undergoing heart surgery in the United States. He was later buried in Ramallah where a shrine was erected in his honour.
Honeymoonish
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UAE currency: the story behind the money in your pockets
