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COVID-19 antibodies vanish fast. That doesn’t mean mass reinfection looms

Experts say disappearing antibodies don’t spell the end of immunity, following seemingly alarming British study

Nathan Jeffay

Nathan Jeffay is The Times of Israel's health and science correspondent

A coronavirus ward at Galilee Medical Center (Ancho Gosh Jini Photo Agency via Galilee Medical Center)
A coronavirus ward at Galilee Medical Center (Ancho Gosh Jini Photo Agency via Galilee Medical Center)

Results of one of the world’s largest COVID studies are generating shockwaves among recovered patients, raising fears of fast-fading immunity. But experts say they shouldn’t jump to conclusions.

English researchers have crunched the numbers from three months of intense antibody testing, and detected a 26.5% drop over time in the proportion of people who had COVID-19 antibodies.

“This very large study has shown that the proportion of people with detectable antibodies is falling over time,” said Helen Ward, an infectious diseases professor who co-authored the study, which ran from June to September, a mostly calm period between the UK’s first and second waves of the pandemic.

The official statements from Imperial College London, which conducted the research, and the British government, which supported it, were cautious about discussing reinfection.

But Ward wrote on Twitter that the results “suggest the possibility of decreasing population immunity, and may indicate increasing risk of reinfection as detectable antibodies decline in the population.”

Hospital workers treat a patient in the coronavirus ward at Shaare Zedek Medical Center in Jerusalem on October 1, 2020. (Nati Shohat/Flash90)

Many recovered patients paid little attention to the tentative nature of her language, and heard alarm bells — especially as the research comes amid a flurry of reports on people getting reinfected. It’s widely assumed that fading antibodies must mean fading immunity, and an inevitable fast-growing spate of reinfections.

Mordechai Gerlic (left) with his colleague Ariel Munitz from Tel Aviv University’s TAU Center for Combatting Pandemics (courtesy of Tel Aviv University)

Tel Aviv University immunologist Mordechai Gerlic said he wasn’t at all surprised that the British researchers found antibodies vanishing.

“This is their nature,” he told The Times of Israel. “Sometimes they last more, but the importance is the memory.”

Commenting on the London results he said: “I don’t really see anything new.”

Gabi Frank, a biophysicist from Ben Gurion University of the Negev, agrees.

“This doesn’t point to the end of immunity,” he told The Times of Israel.

He elaborated: “Antibodies are a response to a challenge, and when there is no longer there, the antibody count will drop, and this is natural and normal, so long as memory remains in the body, which normally happens.”

The leading epidemiologist Michael Edelstein says that had the new research really dropped a bombshell regarding the issue of immunity, there would already be high numbers of people being reinfected — but there aren’t, and reinfection cases are still rare and newsworthy.

He said that the London research, far from suggesting that immunity is vanishing, actually indicates that even when there is a drop in antibodies, recovered COVID patients are being protected from reinfection by various capabilities of their immune system.

Epidemiologist Michael Edelstein (courtesy of Michael Edelstein)

“There were a lot of people infected in March and April, and we’re now months later and there is no mass phenomenon of mass infection,” noted Edelstein, who recently became professor at Bar Ilan University’s medical school after a long stint as a senior official in England’s public health organization. “This would suggest that high levels of this antibody is not sole thing that gives protections, and other means are giving protection beyond the four months during which these levels are high.”

For the study, some 365,000 randomly selected adults tested themselves at home using a finger-prick test between 20 June and 28 September and sent their sample for analysis.

Illustrative: a coronavirus pin-prick test kit. (Tiziana FABI / AFP)

Researchers reported that the first wave of the pandemic in England occurred over a relatively short period in March and April, and that from early April there was a steep decline in the proportion of people who reported having COVID-19 symptoms.

Recovered patients trying to understand the antibody issue are likely to end up confused, particularly as studies on the issue have been contradictory.

While the English researchers stressed a drop in antibodies, a New York medical team just reported, in the peer-reviewed journal Nature, that they are finding that antibodies stay for “many months.”

“While some reports have come out saying antibodies to this virus go away quickly, we have found just the opposite,” said Florian Krammer, professor of vaccinology at the Icahn School of Medicine at Mount Sinai Hospital in New York.

She reported that more than 90 percent of people who were mildly or moderately ill “produce an antibody response strong enough to neutralize the virus, and the response is maintained for many months.”

The New York findings are based on a dataset of 30,082 people who were screened within the Mount Sinai Health System between March and October, 2020.

An Israeli laboratory worker is pictured as she conducts antibody tests for the coronavirus at the Leumit Health Care Services laboratory in Or Yehuda, near Tel Aviv on June 29, 2020. (GIL COHEN-MAGEN / AFP)

Edelstein said the discrepancy between the conclusions highlights that doctors are only just starting to understand immune responses to the disease, and said it is normal to have different results when a new field of research starts.

He commented: “When a new issue arises it’s quite common for different teams to find different results, and that’s why having many people working in the same problem is important.” Details of COVID-19 immunity, he said, are still little-known.

He stressed that while such research has importance for vaccine developers and others who need complex data on the way the body responds to the coronavirus, it’s important to appreciate that neither study actually shows that anyone has been left antibody-less.

“When a virus enters the body, it responds to this by creating different types of antibodies,” he stated. “The immune system will generate antibodies against different parts of the virus, for example the membrane or the spike.”

Illustrative: Red blood cells alongside antibodies in an artery (urfinguss; iStock by Getty Images)

In both studies, researchers only looked at the presence or absence of one particular antibody — the same “spike antibody” in both cases — rather than the whole range of coronavirus antibodies. This means, Edelstein stressed, that even among some people who tested negative, others could well be present.

“It’s like looking at an army in battle, and counting just the foot soldiers and ignoring other parts of the army,” he said. “This doesn’t tell you whether the army is still protecting you, as there are still other parts of the army.”

Edelstein also emphasized that antibody loss is par for the course with diseases. He noted: “For most diseases there is a decline in the level of antibodies that are present. With this virus it seems to happen quite quickly but being able to find that antibodies have reduced does not mean there’s a loss of immunity.”

He said that the extent and duration of COVID-19 immunity simply aren’t known, but in his view it is clear is that neither of the new studies undermines the case for immunity.

Like Gerlic of Tel Aviv University, Edelstein stressed the importance of “memory” arising from antibodies.  “When the body encounters a virus or bacteria it will generate antibodies, and these will slowly disappear,” he said.

“But the body memorizes what the virus looks like using memory cells and these memory cells can protect from future attacks by generating new antibodies when they are needed, or by activating T-cells that are already in the body.”

T-cells are white blood cells which develop in the thymus gland and are increasingly seen by scientists as important in the immune response against the coronavirus.

“The bottom line is that a falling level of antibodies does not necessarily equate with a loss of immunity,” he concluded.

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