COVID-19 antibodies in patients’ blood fade rapidly after symptoms subside, the study found – leaving around a two-week window of opportunity for plasma transfusions
- Immune systems produce antibodies that prevent SARS-CoV-2 from invading cells.
- Preliminary studies suggest that these can be used to help treat severe cases
- Canadian experts study antibody levels in COVID-19 patients’ recovery
- They found these defenses dropped significantly 6-10 weeks after the first symptoms
- Patients can only donate blood plasma two weeks after their symptoms fade
Antibodies produced by the body to fight COVID-19 – this blood transfusion being tested as a treatment for other more severe patients – fade quickly after recovery.
Experts from Canada have studied the blood of coronavirus patients, finding that the extent of immune defenses decreases 6-10 weeks after their initial symptoms.
Blood transfusions have not been proven as a treatment in randomized trials, but small studies have suggested that they may reduce the severity of the disease.
If the so-called ‘convalescent plasma’ is proven to be useful, it means that there is only a small window of opportunity to provide it, researchers warn.
Donors should wait two weeks after symptoms subside before donating blood – to ensure that viral particles are gone – and symptoms usually occur two weeks before this.
As a result, the time frame for plasma donation can be as small as one to two weeks.
Antibodies produced by the body to fight COVID-19 – this blood transfusion being tested as a treatment for other more severe patients – fade quickly after recovery. In the photo, a coronavirus patient donates blood plasma for transfusion to a patient with a severe case
‘We don’t want to catch the virus, just transmit antibodies,’ said paper author and virologist Andrés Finzi of the University of Montreal, Canada.
‘But at the same time, our work shows that plasma’s capacity to neutralize viral grains decreases in those first weeks.’
Key to the way SARS-CoV-2 attacks the body is the so-called spike proteins that cover the virus shell – and allow it to stick to cells and invade them.
However, antibodies produced by the immune system bind to the ends of spike proteins, preventing them from sticking to cells and making the virus ineffective.
Previous studies have suggested that antibodies targeting the coronavirus spike protein peak in the blood around 2-3 weeks after the onset of symptoms – and that the effectiveness of this defense may be lost. a few 4-6 weeks after both.
In their new study, Dr Finzi and colleagues monitored 31 COVID-19 patients – analyzing blood samples taken from each individual at monthly intervals.
For each sample, the researchers measured the levels of antibodies – or ‘immunoglobulins’ – that act against the coronavirus spike protein, in conjunction with testing the ability of these antibodies to neutralize the virus.
Key to the way SARS-CoV-2 attacks the body is the so-called spike proteins that cover the virus shell (pictured) – and allow it to stick to cells and invade them. However, antibodies produced by the immune system bind to the ends of spike proteins, preventing them from sticking to cells and making the virus ineffective.
As the team looked at the differences in patients, they found that in all cases the levels of the three main immunoglobulins targeting the binding site to the spike protein virus fell between 6-10 weeks after symptoms begin.
As the levels of these antibodies fall, so does their ability to neutralize the virus – and, by prolonging it, their potential usefulness within a blood transfusion.
The full findings of the study were published in the journal mBio.