Health Care

Coronavirus immunity could last for years, according to new study

November 20, 2020 15:02·
COVID-19

COVID-19

This research is now present following an announcement that a vaccine being developed by Pfizer is over 90% effective and a second vaccine by Moderna is 94.5% effective.

While the evidence so far on COVID-19 shows a pattern of nine days of infectiousness, researchers did not offer a suggestion as to how long quarantine periods should last, since their study only looked at confirmed cases and not individuals who may have been exposed.

The most cited confirmation came from a July-based King's College Study which found that patients who suffered from COVID experienced a drop in antibody count after 3-4 months time. The researchers said that there was about a 200-fold range in the level of antibody responses among the adults.

These "memory" cells are crucial.

Seventy-nine focused on Sars-CoV-2 (COVID-19), 73 of which only included patients admitted to hospital, eight on SARS, and 11 on MERS.

But that doesn't mean that the body forgets how to make more of them. The researchers said there appeared to be an increase in memory B cells over time.

B cells become specialized factories to pump out antibodies.

They also identified two types of T cells.

The scientists detected B cells in nearly all covid-19 cases.

The La Jolla team followed 185 people - mostly from NY and California - who had been infected with COVID-19, and their various immune cell levels for months after infection.

Delhi reports 98 covid deaths in 24 hours, active cases at 43,221
The death toll due to viral infection in the national capital reached 8,041 after 98 deaths were reported in the last 24 hours. However, infections are rising rapidly in states like Tamil Nadu , Uttar Pradesh and West Bengal.

A Portuguese study found that in the more than the 300 coronavirus patients examined, the antibody response was the strongest in the first three weeks after symptoms.

Most of the group (92 percent) had only mild infections and never needed to be hospitalized.

They found that the longer term form of antibodies, known as immunoglobulin G (IgG) was indeed long-lasting, staying with the survivors and only showing "modest" declines at the six to eight month marks.

Nearly all of the survivors developed memory B cells that were capable of churning out new batches of antibodies if they encountered coronavirus again.

Lead author author Dr. Muge Cevik of the University of St. Andrews, U.K. said in a statement that the new analysis "provides a clear explanation for why SARS-CoV-2 spreads more efficiently than SARS-CoV and MERS-CoV and is so much more hard to contain".

This has even been seen in the handful of rare reinfection cases around the world.

The scientists said that understanding immune memory to SARS-CoV-2 is critical for improving diagnostics and vaccines, and for assessing the likely future course of the pandemic.

The study, which has not yet been peer-reviewed, took into consideration various immune facets, including B cells, antibodies and T cells.

In contrast, the viral loads of SARS and MERS peaked at 10-14 days and seven to 10 days after symptom onset respectively, explaining why transmission of these viruses can be effectively reduced by immediate identification, isolation and quarantine of people who show symptoms.

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