#COVID19#immunity#coronavirus
One of the big questions about coronavirus deals with immunity.
How long does immunity last?
Who develops immunity?
And can we use immunity as a “passport”?
Meaning people can work, travel and have the freedom to do anything if they have immunity to the virus.
There are some emerging studies that provide us with some clues.
For example, a study published in the journal nature medicine shows immunity could last for up to 3 months.
Based on a study that was done in China, people who develop antibodies after becoming infected with the coronavirus may not keep them more than a few months.
And this is the case especially if a person did not show symptoms when infected.
We know from previous studies that most people who became infected developed antibodies.
And governments and health organizations around the world use antibody tests to find out if a person has been exposed to the virus.
The study from China looked at 37 people who became infected with the coronavirus and showed symptoms.
For comparison, they also looked at 37 people who became infected and showed no symptoms.
Eight weeks after recovery, antibody levels fell to undetectable levels in 40% of asymptomatic people.
But the antibody fell to 13% in symptomatic people.
Meaning, people who did not show symptoms when infected had lower antibody levels, which is not surprising.
In this study, they only looked at antibody levels.
But the authors also recognize that the body can use other things like T cells to kill the virus.
For antibodies, our body produces both IgM and IgG.
IgM indicates early exposure to the virus while IgG is a better indicator of long-term immunity.
According to the study, after 8 weeks, there is a 71% median drop for IgG levels in the asymptomatic group and a 76% median drop in the symptomatic group.
Long, Q., Tang, X., Shi, Q. et al. Clinical and immunological assessment of asymptomatic SARS-CoV-2 infections. Nat Med (2020).
