Immune system of recovered COVID-19 patients may evolve to fight coronavirus variants: Study
New York: People who recover from COVID-19 are protected against the novel coronavirus for at least six months, and likely much longer, according to a study which says the immune system evolves long after the infection and may block even mutant forms of the virus such as the South African variant.
The research, published in the journal Nature, noted that antibodies are produced by immune cells that keep evolving, apparently due to a continued exposure to remnants of the virus hidden in the gut tissue.
According to the scientists, including those from Rockefeller University in the US, the study provides the "strongest evidence yet" that the immune system "remembers" the virus and, remarkably, continues to improve the quality of antibodies even after the infection has waned.
They suspect that when recovered patients next encounters the virus, the response would be both faster and more effective, preventing reinfection.
"This is really exciting news. The type of immune response we see here could potentially provide protection for quite some time, by enabling the body to mount a rapid and effective response to the virus upon re-exposure," says Michel C. Nussenzweig, a co-author of the study from Rockefeller University.
While antibodies against the coronavirus linger in the blood plasma for several weeks or months, earlier studies have shown that their levels significantly drop with time.
However, the researchers showed that instead of producing antibodies all the time, the immune system creates memory B cells that recognise the coronavirus, and quickly unleash a new round of antibodies when they encounter it a second time.
Since the novel coronavirus replicates in the cells of the lungs, upper throat, and small intestine, they suspect that residual viral particles hiding within these tissues could be driving the evolution of memory B cells.
In the current study, the scientists studied the antibody responses of 87 individuals at two timepoints -- one month after infection, and then again six months later.
Although antibodies were still detectable by the six-month point, their numbers had markedly decreased, with lab experiments revealing that the ability of the participants' plasma samples to neutralise the virus was reduced by five-fold.
In contrast, the researchers found that the patients' memory B cells -- specifically those that produce antibodies against the coronavirus -- did not decline in number.
These cells also slightly increased in some cases, the study noted.
The scientists also discovered that the memory B cells had gone through numerous rounds of mutation even after the infection resolved.
As a result, the antibodies they produced were much more effective than the originals, the study noted.
According to the researchers, these antibodies were better able to latch on tightly to the virus, and could recognise even mutated versions of it.
"The overall numbers of memory B cells that produced antibodies attacking the Achilles' heel of the virus, known as the receptor-binding domain, stayed the same," said Christian Gaebler, another co-author of the study.
"That's good news because those are the ones that you need if you encounter the virus again," Gaebler said.
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Bengal awaits May 4 results; TMC looks to retain power, BJP aims historic win after record turnout
Kolkata (PTI): West Bengal heads into verdict day on Monday after over a month of frenzied campaigning, as it waits with bated breath to see whether the TMC manages to hold on to power or the BJP makes a historic breakthrough and claims the state for the first time.
As the EVMs open at 8 am, the CPI(M) and the Congress will be watching with equal keenness, hoping to reclaim a foothold in the state's electoral map after five years in the wilderness, following their wipeout in the 2021 polls.
Counting of votes will take place across 77 centres in the state, with elaborate security arrangements and a charged political atmosphere setting the stage for the declaration of results in 293 of the 294-seat House.
The Election Commission countermanded polls in the entire Falta constituency in South 24 Parganas district, citing “severe electoral offences and subversion of democratic process during polling in a large number of polling stations”.
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The fresh poll in that seat and the counting will take place on May 21 and May 24, respectively.
The two-phase polls in the state ended on April 29, with what the election watchdog said was the state's highest-ever voter turnout of 92.47 per cent since Independence.
Repolling in 15 booths in South 24 Parganas concluded on Saturday, with around 87 per cent turnout recorded, officials said.
The state’s political climate bordered on the vicious, even after the conclusion of polls, leading to fervent anticipation ahead of the announcement of results, with both primary contenders TMC and BJP, claiming they were dead certain about their victory prospects.
Courtesy the tight security arrangements – with over 2.5 lakh central paramilitary personnel on the ground, besides the presence of a thoroughly reshuffled state police force – electoral violence remained at a minimum, and no deaths were reported for the first time in the state’s election history of recent decades.
This was also the first election held in the state in twenty years, conducted after an extensive, albeit controversial, SIR exercise that revised the electoral rolls, removing over 9 million voters.
The jury is out on the impact of the exercise on the electoral fortunes of all parties across the board, prompting pollsters to burn the midnight oil to make sense of the likely choice of voters and keeping the public greatly enthused about what verdict the result day would deliver.
The campaigns recorded the BJP unleashing its full might, with top leaders like Prime Minister Narendra Modi, Union Home Minister Amit Shah and Defence Minister Rajnath Singh launching all-out attacks on the TMC over corruption, law and order, infiltration, women’s safety and unemployment, while promising welfare measures.
The TMC’s retaliation, with the CM and party MP Abhishek Banerjee leading the charge, focused on SIR harassment, Bengali persecution and ‘outsider’ plank, accusing the BJP of failing to deliver on its national commitments and upholding TMC’s development report card.
Polling for the elections was held on April 23 and April 29, with a total electorate of over 3.21 crores.
The poll body has scaled down the number of counting centres this year to 77 from 87 announced earlier, and 108 in 2021, while putting in place a multi-layered security grid.
“Comprehensive security arrangements have been made to ensure that counting is conducted in a peaceful, transparent and orderly manner,” a senior EC official said.
The run-up to counting, however, has been marked by high political drama, with TMC leaders, helmed by CM Mamata Banerjee, rushing to strongrooms in Kolkata, apprehending counting malpractice and alleging attempts to tamper with the sealed EVMs.
The EC rejected those allegations, maintaining that all electronic voting machines are kept under strict surveillance with round-the-clock security and CCTV monitoring.
“Strongrooms are secured under a three-tier security system, and candidates or their representatives are allowed to keep watch as per protocol. There is no scope for any tampering,” another poll panel official said.
Closer to the counting date, security outside strongrooms has been further tightened, with the EC deploying 165 additional counting observers and 77 police observers to oversee the process and ensure adherence to norms.
In Kolkata, counting for 11 assembly constituencies will be conducted across five locations - Ballygunge Government High School, Baba Saheb Ambedkar Education University, Shakhawat Memorial School, Netaji Indoor Stadium and St Thomas Boys’ School.
Counting for the Bhabanipur seat, arguably carrying the highest symbolic weight where Mamata Banerjee is taking on senior BJP leader Suvendu Adhikari in a prestige fight on her home turf, will be held at the Sakhawat Memorial centre.
The EC has introduced stringent access control measures, mandating entry only through QR code-based photo identity cards issued via its ECINet system. Mobile phones have been barred inside counting halls, except for returning officers and observers.
The counting exercise will be conducted under a framework upheld by the Supreme Court, which on Saturday declined to pass further directions on a TMC plea challenging the deployment of central government personnel.
The elections saw the TMC contesting in 291 seats and its ally Bharatiya Gorkha Prajatantrik Morcha (BGPM), led by Anit Thapa, fielding candidates in three seats in the Darjeeling hills.
The BJP, Congress and the Left Front are gunning for all 294 segments, with parties like Humayun Kabir’s AJUP and Asaduddin Owasi’s AIMIM also trying their luck in some crucial pockets.
BJP leaders like Dilip Ghosh, Agnimitra Paul, Roopa Ganguly and Nishit Pramanik are in the fray, while prominent TMC candidates include Firhad Hakim, Kunal Ghosh, Madan Mitra and Udayan Guha.
