- How long does the antibody immunity of "Covid-19" survivors last before they are exposed to a second infection?

How long does the antibody immunity of "Covid-19" survivors last before they are exposed to a second infection?

The Centers for Disease Control and Prevention previously suggested that those recovering from "Covid-19" may have some immunity to the virus.

But updated guidance from the American Health Organization indicates that this protection may not last more than three months.

People who have tested positive for COVID-19 do not need to be quarantined or tested again for up to three months as long as they do not show symptoms again, '' says the Centers for Disease Control (CDC) guidelines, which were recently updated.

However, "people who develop symptoms again within 3 months of the first COVID-19 episode may need to be tested again if there is no other specific cause for their symptoms."

And the instructions indicate that, that recovery provides some protection, but for a limited period, and that re-infection is possible.

And scientists around the world are still trying to find out how much antibody a person develops to fight the Corona virus.

Most estimates ranged from a few weeks to a few months.

A new large American study indicates that convalescent plasma, which is a part of blood rich in antibodies, from Corona virus survivors has improved the survival prospects and recovery times for people who are still fighting "Covid-19", indicating that immune cells are working, At least after a short period of healing.

The levels of antibodies present in recovered "Covid-19" patients fell sharply within 2 to 3 months after infection for each of the asymptomatic or asymptomatic patients, according to a Chinese study published in Nature Medicine last June.

Researchers from Chongqing Medical University said that it has highlighted the dangers of using "immune passports" for "Covid-19" and supports the prolonged use of public health interventions such as social distancing and isolation of at-risk groups.

The results, which studied 37 patients with symptoms and 37 patients without apparent symptoms, found that among those who were found to have IgG antibodies, which is one of the main types of antibodies that are stimulated after infection, more than 90% showed a sharp decrease within 2 Up to 3 months.

The average decrease, in percentage terms, was more than 70% for each of the patients with or without symptoms.

To neutralize the antibodies in the blood, the average percentage decrease for symptomatic individuals was 11.7% while it was 8.3% for asymptomatic individuals.
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Scientists had hoped that the antibodies to SARS-CoV-2 would have similar survival strength to the immunity seen in people with their cousins, such as SARS and MERS.

Antibodies to each last for at least a year, and SARS antibody levels remain stable for up to two years after infection before they start to decline. This has not been proven to be the case in the new study on "Covid-19".

Most of the Covid-19 patients had low levels of antibodies within two months.

Four out of eight patients the researchers followed during the 'recovery' phase (meaning that they have recovered, but may still have signs of the virus inside their bodies) lost most of their antibody protection within six to seven weeks.

The short-term protection offered by the coronavirus antibodies proposed by the new study means that even a person who contracted the coronavirus in March may now be already susceptible to infection again.

Jin Dong Yan, a professor of virology at Hong Kong University who was not part of the research group, said the study does not deny the possibility that other parts of the immune system might provide protection.

He indicated that some cells memorize how to deal with the virus when it is first infected and can obtain effective protection in the event of a second wave of infection.

Scientists are still investigating whether this mechanism works with the new Corona virus.

Dr. Yan urged not to worry, noting that the number of patients studied was small.

It is clear what the level of protective antibodies is, although more antibodies definitely means more protection.
Source: Daily Mail