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Coronavirus antibodies dwindled to undetectable levels after just 2 or 3 months for 40% of asymptomatic people and 13% of symptomatic people.
Overall, asymptomatic people showed "a weaker immune response" in the months after they were exposed to the coronavirus.
A poor immune response in people who recover from the virus may not bode well for the development of an effective vaccine.
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Common cold virses can give antibodies to SARS-COV-2 virus
Preexisting and de novo humoral immunity to SARS-CoV-2 in humans
Immunological memory after infection with seasonal human coronaviruses (hCoVs) may potentially contribute to cross-protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Ng et al. report that in a cohort of 350 SARS-CoV-2–uninfected individuals, a small proportion had circulating immunoglobulin G (IgG) antibodies that could cross-react with the S2 subunit of the SARS-CoV-2 spike protein (see the Perspective by Guthmiller and Wilson). By contrast, COVID-19 patients generated IgA, IgG, and IgM antibodies that recognized both the S1 and S2 subunits. The anti-S2 antibodies from SARS-CoV-2–uninfected patients showed specific neutralizing activity against both SARS-CoV-2 and SARS-CoV-2 S pseudotypes. A much higher percentage of SARS-CoV-2–uninfected children and adolescents were positive for these antibodies compared with adults. This pattern may be due to the fact that children and adolescents generally have higher hCoV infection rates and a more diverse antibody repertoire, which may explain the age distribution of COVID-19 susceptibility.
Zoonotic introduction of novel coronaviruses may encounter preexisting immunity in humans. Using diverse assays for antibodies recognizing SARS-CoV-2 proteins, we detected preexisting humoral immunity. SARS-CoV-2 spike glycoprotein (S)–reactive antibodies were detectable using a flow cytometry–based method in SARS-CoV-2–uninfected individuals and were particularly prevalent in children and adolescents. They were predominantly of the immunoglobulin G (IgG) class and targeted the S2 subunit. By contrast, SARS-CoV-2 infection induced higher titers of SARS-CoV-2 S–reactive IgG antibodies targeting both the S1 and S2 subunits, and concomitant IgM and IgA antibodies, lasting throughout the observation period. SARS-CoV-2–uninfected donor sera exhibited specific neutralizing activity against SARS-CoV-2 and SARS-CoV-2 S pseudotypes. Distinguishing preexisting and de novo immunity will be critical for our understanding of susceptibility to and the natural course of SARS-CoV-2 infection.
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Only 5% in Spain developed antibodies to natural infection
Seroprevalence was 5·0% (95% CI 4·7–5·4) by the point-of-care test and 4·6% (4·3–5·0) by immunoassay, with a specificity–sensitivity range of 3·7% (3·3–4·0; both tests positive) to 6·2% (5·8–6·6; either test positive), with no differences by sex and lower seroprevalence in children younger than 10 years (<3·1% by the point-of-care test). There was substantial geographical variability, with higher prevalence around Madrid (>10%) and lower in coastal areas (<3%). Seroprevalence among 195 participants with positive PCR more than 14 days before the study visit ranged from 87·6% (81·1–92·1; both tests positive) to 91·8% (86·3–95·3; either test positive). In 7273 individuals with anosmia or at least three symptoms, seroprevalence ranged from 15·3% (13·8–16·8) to 19·3% (17·7–21·0). Around a third of seropositive participants were asymptomatic, ranging from 21·9% (19·1–24·9) to 35·8% (33·1–38·5). Only 19·5% (16·3–23·2) of symptomatic participants who were seropositive by both the point-of-care test and immunoassay reported a previous PCR test.
The majority of the Spanish population is seronegative to SARS-CoV-2 infection, even in hotspot areas. Most PCR-confirmed cases have detectable antibodies, but a substantial proportion of people with symptoms compatible with COVID-19 did not have a PCR test and at least a third of infections determined by serology were asymptomatic. These results emphasise the need for maintaining public health measures to avoid a new epidemic wave.
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Waning antibody immunity to COVID-19
Discussion
These findings provide evidence of variable waning in antibody positivity over time such
that, at the start of the second wave of infection in England, only 4.4% of adults had
detectable IgG antibodies using an LFIA. Antibody positivity was greater in those who
reported a positive PCR and lower in older people and those with asymptomatic infection.
These data suggest the possibility of decreasing population immunity and increasing risk of
reinfection as detectable antibodies decline in the population.
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Reinfections More Likely With New Coronavirus Variants, Evidence Suggests. No herd immunity.
January 21, 2021
Back in April, COVID-19 hit the city of Manaus, Brazil, extremely hard. In fact, the outbreak there was arguably the worst in the world. One study, published in the journal Science, estimated that so many people were infected that the city could have reached herd immunity — that the outbreak there slowed down because up to 76% of the population had protection against the virus.
Now the city of Manaus is seeing another massive surge in cases. This time around, the outbreak appears even larger than the first one, says Marcus Vinicius Lacerda, an infectious disease doctor at the Fundação de Medicina Tropical Doutor Heitor Vieira Dourado in Manaus. "You have much more people becoming infected and that includes people inside their [newly diagnosed patients'] households," he says.
The surge is so large that hospitals have run out of oxygen, and patients on ventilators, who need extra oxygen to breathe, have literally suffocated in hospital beds. "I'm really afraid. I'm seeing lots of people dying, people that should have had better support in the hospitals," Lacerda says.
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Asymptomatic cases of infection result in zero antibodies developing
Only those with symptoms develop antibodies.
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Concerns persist that COVID-19 vaccines could cause antibody-dependent enhancement, which can potentiate viral entry into host cells and worsen disease.
In late May, CanSino Biologics published the first data for its COVID-19 vaccine expressing spike protein. The vaccine generated neutralizing antibodies in many recipients and appeared safe, but the company, like others in this space, remains on alert for a dangerous phenomenon known as antibody-dependent enhancement (ADE). “It’s important to talk about it [ADE],” says Gregory Glenn, president of R&D at Novavax, which launched its COVID-19 vaccine trial in May. But “we can’t be overly cautious. People are dying. So we need to be aggressive here.”
There are mounting theoretical concerns that vaccines generating antibodies against SARS-CoV-2 may bind to the virus without neutralizing it. Should this happen, the non-neutralizing antibodies could enhance viral entry into cells and viral replication and end up worsening infection instead of offering protection, through the poorly understood phenomenon of ADE. ADE “is a genuine concern,” says virologist Kevin Gilligan, a senior consultant with Biologics Consulting, who advises thorough safety studies. “Because if the gun is jumped, and a vaccine is widely distributed that is disease enhancing, that would be worse than actually not doing any vaccination at all.”
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Covid: Antibodies 'fall rapidly after infection'
The Imperial College London team found the number of people testing positive for antibodies has fallen by 26% between June and September.
They say immunity appears to be fading and there is a risk of catching the virus multiple times.
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Asymptomatic COVID-19 findings dim hopes for vaccines, 'herd immunity' and 'immunity passports'
Antibodies few and short-lived, lung abnormalities found in asymptomatic carriers.
A new study on COVID-19 immunity has found that people who were asymptomatic or mildly symptomatic had their antibodies diminish within two to three months. Though larger studies are needed, the findings cast doubt on antibody testing and herd immunity.
A closer look at people who tested positive for COVID-19 but never developed symptoms has found that such asymptomatic carriers have few to no detectable antibodies just weeks after infection, suggesting they may not develop lasting immunity.
There's growing evidence that a significant proportion of people who test positive for COVID-19 never show symptoms, although it's not clear what percentage of people that is and what role they play in spreading the disease.
A Chinese study published this week in Nature followed 37 people in Wanzhou District in China who did not show any outward signs of the disease, despite testing positive when their respiratory tracts were swabbed and being kept in hospital for observation.
The study also found that despite having no outward symptoms, 70 per cent had lung abnormalities detectable in X-rays at some point during infection — mostly spots called "ground-glass opacities," which can indicate inflammation or other signs of disease.
What was "a little bit surprising," he said, was the fact that 40 per cent of people with asymptomatic infections had no detectable antibodies at all.
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German research suggests infection offers little immunity to coronavirus
A research projected completed in the German state of Bavaria found that people infected with coronavirus lose their antibodies to the virus just months after beating the disease, giving rise to concerns about the effectiveness of vaccinations and herd immunity.
The research project, completed by the Munich Clinic Schwabing, found that the concentration of antibodies in the blood decreases rapidly in the months following an infection.
The findings dampen hope of long-lasting immunity for those who have beaten the virus.
The findings give credence to reports out of South Korea and China that some people had been infected with the virus despite having previously recovered from it.
The project looked at patients who had recovered from the virus from January onwards.
It found that while neutralising antibodies were formed in the blood during the time in which the person was infected, these declined in the following months.
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Here’s what they forgot to tell you about the risks
But moderate or severe harms—defined as being bad enough to interfere with daily life or needing medical care—were common too. Around one-third of people vaccinated with the Covid-19 vaccine without acetaminophen experienced moderate or severe chills, fatigue, headache, malaise, and/or feverishness. Close to 10 percent had a fever of at least 100.4 degrees, and just over one-fourth developed moderate or severe muscle aches. That’s a lot, in a young and healthy group of people—and the acetaminophen didn’t help much for most of those problems. The paper’s authors designated the vaccine as “acceptable” and “tolerated,” but we don’t yet know how acceptable this will be to most people.
On May 18, Moderna put out some patchy, positive findings on interim outcomes from their first-in-human trial. The company followed that up with a stock offering—and company executives sold off nearly $30 million in shares into the feeding frenzy their press release created.
By the time they’d had two doses [of the Moderna vaccine], every single one was showing signs of headaches, chills, or fatigue, and for at least 80 percent, this could have been enough to interfere with their normal activities. A participant who had a severe reaction to a particularly high dose has talked in detail about how bad it was: If reactions even half as bad as this were to be common for some of these vaccines, they will be hard sells once they reach the community—and there could be a lot of people who are reluctant to get the second injection.
This week, a new preprint from Kin On Kwok and colleagues found that even a sizable proportion of nurses in Hong Kong would be hesitant to take one.
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