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Immunity is the crucial question and understanding it will tell us how the pandemic will end.
Immunity could affect vaccine research
Have people caught it twice?
were early reports
of people appearing to have multiple coronavirus infections in a short space of time.
But the scientific consensus is that testing was the issue, with patients being incorrectly told they were free of the virus.
Nobody has been deliberately reinfected with the virus to test immunity, but a pair of rhesus macaque monkeys have.
They were infected twice, once to build up an immune response and then a second time three weeks later. Those very limited experiments showed they
after such a quick reinfection.
If I have antibodies am I immune?
This is not guaranteed and that is why the World Health Organization is
nervous about countries using immunity passports
as a way out of lockdown.
The idea is if you pass the antibody test then you are safe to go back to work. This would be particularly valuable for staff in care homes or hospitals who come into contact with those at risk of developing severe symptoms.
But while you will find some antibodies in nearly every patient, not all are equal. Neutralising antibodies are the ones that stick to the coronavirus and are able to stop it infecting other cells. A study of 175 recovered patients in China
showed 30% had very low levels
of these neutralising antibodies.
That is why the World Health Organization says”that cellular immunity [the other part of the adaptive response] may also be critical for recovery”.
Another issue is that just because you might be protected by your antibodies, it doesn’t mean you cannot still harbour the virus and pass it onto others.
Why does immunity matter?
It matters for obvious personal health reasons and whether you will get Covid-19 multiple times and how often.
Immunity will also affect how deadly the virus is. If people retain some, even imperfect, protection then it will make the disease less dangerous.
Understanding immunity could help ease lockdown if it is clear who is not at risk of catching or spreading the virus.
If it is very difficult to produce long-term immunity, then it could make a vaccine harder to develop. Or it may change how the vaccine needs to be used – will it be a once a lifetime or once a year like the flu shot.
And the duration of immunity, whether by infection or immunisation, will tell us how likely we are to be able to stop the virus spreading.
These are all big questions we still lack answers to.
For More Details : BBC Health News