A three-month study suggests antibody response to the coronavirus falls over time, leading to a possible decline in immunity. But it remains unclear how great the chance of a second infection is.
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In tests carried out on 365,104 people in England from June to September, the number of people testing positive for coronavirus antibodies dropped by 26.5%.
The study, known as REACT, was led by Imperial College London. It used a finger-prick test to check for antibodies in the blood. Antibodies show that a person has been previously infected with a virus, and in this case, the virus that causes COVID-19.
Results from the group of randomly selected volunteers showed a "downward trend in all areas of the country and age groups."
In a preprint paper, the scientists said the "data suggest the possibility of decreasing population immunity and increasing risk of reinfection as detectable antibodies decline in the population."
The study has yet to be peer reviewed or verified by other scientists and COVID-19 experts.
The UK has seen a sharp rise in new coronavirus infections, with many areas going into renewed lockdownImage: AFP via Getty Images
Professor Paul Elliott, a co-author of the paper, said the connection between coronavirus antibodies and immunity against reinfection "remains unclear."
The test and its results
Three rounds of tests were carried out at 12, 18 and 24 weeks after the first peak of SARS-CoV-2 infections in England.
Once registered for the study, participants were sent a Lateral Flow Test kit, which they self-administered to provide a blood sample from a finger prick.
They then answered a questionnaire. The scientists say the participants were not "blind" to their results and, as a result, may have added bias to their answers. But the study authors also say that "should not have affected our observation of declining prevalence [of coronavirus antibodies] over time."
Results showed a decline between rounds one and three in all age groups. The highest prevalence of a positive result and smallest overall decline in positivity were in the youngest age group of 18-24 years.
The lowest prevalence and largest decline in antibodies were in the oldest group of 75 years and above. There was no change in antibody positivity between rounds one and three in health care workers.
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"During any antibody response to an acute pathogen, some level of antibody waning in the months following infection is expected as short-lived plasma cells die," the study authors wrote. "Low levels of affinity-matured antibody usually continues to be produced by long-lived plasma cells and may be sufficient to maintain levels of antibody that confer immunity."
The first, REACT1, involves antigen (swab) tests, with the aim of examining how widely the virus has spread and how many people are currently infected with it.
REACT2 is assessing different antibody tests to see how accurate they are and how easily people can use them at home.
Antigens are viruses or bacteria that can cause an immune response in the body. Antibodies are then produced by the body as a response to an infection.
Coronavirus: Politicians who've tested positive
French President Emmanuel Macron is the latest top-tier politician to come down with a case of COVID-19. He's the latest among several, perhaps unsurprisingly given politicians' busy schedules and frequent travel.
Image: Olivier Hoslet/REUTERS
Emmanuel Macron
French President Emmanuel Macron tested positive for the virus on December 17. Following the diagnosis, he canceled all of his upcoming trips, including one to Lebanon, and said he would self-isolate for seven days. French Prime Minsiter Jean Castex was also set to isolate after coming into contact with Macron.
Image: Olivier Hoslet/REUTERS
Andrzej Duda
Polish President Andrzej Duda tested positive for coronavirus in October, as the country was facing surge in new infections. Duda, an ally of the ruling nationalist Law and Justice Party, was "feeling fine" at the time of the diagnosis. The day before officials announced his infection, the number of new cases in the country of 38 million hit a daily record of more than 13,600.
Image: Reuters/A. Szmigiel
Donald Trump
Donald Trump, who once said COVID-19 tests were "beautiful," tested positive for the coronavirus, along with his wife Melania, soon after senior aide Hope Hicks also contracted the virus. The infection came less than a month before November's presidential elections in the US.
Image: Doug Mills/abaca/picture alliance
Ambrose Dlamini
Prime Minister of Eswatini Ambrose Dlamini died at the age of 52 after contracting coronavirus. He was the first sitting leader to succumb to the virus.
Image: RODGER BOSCH/AFP
Valery Giscard d'Estaing
Former French President Valery Giscard d'Estaing died aged 94 on December 2 after contracting COVID-19. During his rule, he legalized abortion and brought the country high-speed trains. He also promoted cooperation among European nations, especially in tandem with the former West Germany, forging a strong rapport with Chancellor Helmut Schmidt.
Image: Stephane De Sakutin/AFP/Getty Images
Silvio Berlusconi
The 83-year-old former Italian premier tested positive for the virus and is believed to be asymptomatic, his party announced on September 2. Two of Berlusconi's children as well as his 30-year-old girlfriend are also COVID-19 positive. The ex-premier tested positive after vacationing along Sardinia's coastline, where Italy's rich and famous have been known to flaunt mask policies.
Image: picture-alliance/dpa/D. Vojinovic
Jair Bolsonaro
Brazil's president, who has repeatedly downplayed the severity of the pandemic, contracted the virus in July. He was criticized for ignoring the safety measures recommended by health experts both before and after his diagnosis, including shaking hands and hugging supporters in crowds. His wife and sons also tested positive.
Image: picture-alliance/dpa/E. Peres
Boris Johnson
In late March, British Prime Minister Boris Johnson came down with a coronavirus infection that landed him in the hospital for several days. Johnson spent a week at a hospital in London and three nights in intensive care where he was given oxygen and observed around the clock. He was released in mid-April and credited hospital staff with saving his life.
Image: picture-alliance/AP Photo/S. Dawson
Michel Barnier
Michel Barnier, the EU's chief Brexit negotiator, tested positive for the virus in March. The top Brussels official sent out a tweet in English as well as French saying he was doing well and "in good spirits." He added: "I am following all the necessary instructions, as is my team."
Image: Reuters/Y. Herman
Alexander Lukashenko
Belarus's embattled President Lukashenko told military officials on July 28 that he had survived an "asymptomatic" COVID-19 infection "on his feet," days before his contentious re-election. The claim met skepticism given its timing. He initially dismissed fears about the pandemic as a "psychosis" and went as far as suggesting cures such as drinking vodka, taking saunas and playing ice hockey.
Image: picture-alliance/Russian Look/V. Listsyn
Jeanine Anez
Bolivia's interim president Jeanine Anez announced on July 10 that she had the virus. "I feel well, I feel strong, I am going to keep working remotely from my isolation, and I want to thank all the Bolivians who are working to help us in this health crisis," the leader tweeted at the time.
Image: AFP
Juan Orlando Hernandez
The president of Honduras spent time being treated at a military hospital after falling ill with coronavirus in June. He received specialized care including receiving medicines via an intravenous drip. His wife and two presidential aids also tested positive. Hernandez left hospital in early July after his symptoms improved.
Image: picture-alliance/AP Photo/J. Martin
Alejandro Giammattei
The Guatemalan president told local radio on September 18 that he had tested positive for the virus. The 64-year-old, who has multiple sclerosis and uses canes to walk, said his symptoms were mild. The government said Giammattei plans on monitoring his health and continuing official duties from isolation.
Image: Johan Ordonez/AFP
Abdelmadjid Tebboune
Algerian President Abdelmadjid Tebboune was flown to Germany hospital for treatment after contracting the virus. The 74-year-old looked haggard and spent in his public appearance 47 days after testing positive.
Image: Ryad Kramdi/AFP
Luis Abinader
Luis Abinader, the newly elected president of the Dominican Republic, tested positive during his election campaign. He recovered before the July election and spent one week in isolation.
Image: Getty Images/AFP/O. Barria
Jens Spahn
German Health Minister Jens Spahn, who has led Germany's fight against the pandemic, tested positive for the coronavirus in October and had "cold-like symptoms." He went into immediate isolation and soon recovered. Despite a couple of self-isolation scares for Angela Merkel and other ministers, Spahn remains Germany's highest-profile political case to date.
Image: Daniel Karmann/dpa/picture alliance
Not an exhaustive list
This gallery does not include all major politicians who have contracted the coronavirus. Others, such as Bulgarian Prime Minister Boyko Borissov, Moldovan Prime Minister Ion Chicu, Armenian Prime Minister Nikol Pashinyan, and Croatian Prime Minister Andrej Plenkovic, are just some of the other top politicians who have contracted the virus.
