New study offers more evidence that immunity to Covid-19 wears off quickly
This is the first article in a three-part series on mitigating immunity against Covid-19 and influenza – the science behind it and its implications for vaccine development and the pandemic in general. . Read the second part here and the final part here.
More and more evidence has emerged that immunity to Covid-19 wears off quickly – in people of all ages, but more for the elderly than the young.
A recent publication British study, currently under peer review, found that the prevalence of Covid-19 antibodies across England fell by more than 26% in three months. The results come from 365,000 home tests that were sent to participants in three rounds, distributed randomly each time.
Antibody tests, which measure proteins your body makes to ward off a specific pathogen rather than a live virus, have been used throughout the pandemic to detect infections that standard PCR tests fail to detect. This is especially useful for detecting so-called silent spreaders – asymptomatic carriers who are not tested because they do not get sick, but can cause up to 80 percent infections.
The fastest drop in antibodies seen in the UK study, in fact, was in people who did not report a history of symptoms of Covid-19, in other words, asymptomatic participants. Antibody levels in this group fell by almost two-thirds between the first round of tests and the last, while those of people who tested positive for the disease fell by just over 20%.
Another notable drop was seen in a population that, while these antibodies are protective, need them the most: participants aged 75 and over. Their antibodies are down by almost 40 percent. Among participants in the youngest age group (18-24), the decline was much smaller, at around 15%. In only one group, health workers, rates remained stable; this may be due to their increased exposure to the virus.
The UK study is the latest to join a group of body Of research which comes to the same conclusion – that the antibodies we make against SARS-CoV-2, the virus that causes Covid-19, are short lived. A to study, Posted in Natural medicine in June, measured antibody levels in a group of 37 Covid-19 patients three to four weeks after the initial infection and then two months thereafter. Surprisingly, around 20 percent tested negative for antibodies in total, indicating either complete disappearance or levels so low that they are undetectable.
These conclusions were repeated in another to study published in JAMA last month on healthcare workers who work directly with Covid-19 patients at Vanderbilt University Medical Center in Nashville, Tennessee. Almost 60% of those who tested positive for anti-SARS-CoV-2 antibodies in April were negative just two months later. Once again, their antibody levels had dropped so much that they were no longer detectable.
Since it is not known whether these antibodies are even protective against the virus in the first place, it is difficult to say for sure whether the rapid dissipation of the antibody response leaves the body vulnerable to reinfection. But it would hardly be surprising if this was the case. In addition to occasionally transforming to become highly transmissible and deadly threats to humanity, seasonal coronaviruses have another hallmark: their ability to re-infect the same person not just once, but two or three times, as evidenced by research of 1970s and 1980s and a much newer 2018 to study conducted in Kenya.
There have been reports that the T cell response against coronavirus infections, including those caused by SARS-CoV-2, lasts longer than the antibody response. T cells are a type of white blood cell that, like antibodies, is essential to our ability to prevent future encounters with a harmful virus. In the case of seasonal cold-inducing coronaviruses, however, T-cell memory has little to no effect in preventing reinfection, which can happen like clockwork every year. The lack of protective antibodies doesn’t bode well for T cell immunity no matter how you spin it.
A handful of Covid-19 re-infections have already been confirmed by genome sequencing in Hong Kong and United States and reported anecdotally in Europe, India, and South Korea. Now that a second wave of infections has engulfed Europe and a third is crashing into the United States, we would be remiss to rule out the possibility that subsequent waves of Dinfection could exacerbate present and future epidemics. Not only does all of this dispel the dangerous fantasy of collective immunity, it also complicates a near-inevitability looming on the horizon: the coincidence of the ongoing Covid-19 pandemic with the arrival of the seasonal flu.
It turns out that antibodies to Covid-19 aren’t the only ones declining rapidly. Those produced by standard influenza vaccines, new studies spectacle, disappear to a similar clip. I will explore the implications of this finding, both in the context of influenza research and the current health crisis, in the next part of this series.