How long does the so-called natural immunity against coronavirus disease last?
This is a question everyone is asking, especially those who hired Covid-19 and recovered.
It turns out to last at least 6 to 7 months, but between 20% and 30% of those infected lose this immunity after 6 months, according to research from the Institute of Genomics and Integrative Biology (IGIB).
“The key finding of 20-30% of subjects who lost virus-neutralizing activity, despite remaining HIV-positive, at 6 months of follow-up helps to understand why the big second wave has not saved cities like Bombay with high HIV-positivity “, said Dr. Anurag Agarwal of the IGIB said in a tweet.
The research is important because it could explain the timing of the second wave of the disease, such as the one India is witnessing right now.
It is also important because it emphasizes the importance of vaccines. Research is ongoing, but it is believed that most of the vaccines currently in use protect people from serious infection and death for at least a couple of years.
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Researchers say the fines may explain why cities like Mumbai and Delhi are experiencing a sharp rise in cases of viral infection despite having high seropositivity or antibodies. Delhi was found to have an average HIV status of just over 56% in January, which doctors in the city believe was the reason for the slowdown in the pandemic following the November rise.
On Saturday, Delhi registered 7,897 new cases and Bombay, 9,327.
The IGIB study also established that seropositivity was inversely proportional to the positivity rate of the test. This means that a higher prevalence of antibodies leads to a decrease in transmission.
In September, when we conducted a serotest study in the laboratories of the CSIR (Council for Scientific and Industrial Research), it was found that just over 10% of participants had antibodies against the virus. We then monitored a fraction of these participants for three to five to six months and performed a quantitative test to check their antibody levels, ”said Dr. Shantanu Sengupta, senior IGIB scientist. and one of the authors of the study accepted for publication. Saturday at the eLife newspaper.
“At five or six months, almost 20% of the participants had lost their neutralizing activity despite having antibodies; the neutralizing activity of the rest also decreased.” Neutralization is the ability of the antibody to kill the virus or prevent it from completely entering a cell.
Of the 10,427 study participants, 1,058 or 10.14% tested positive for antibodies in September last year. The researchers tracked 175 of the 1058 for five or six months and found that 31 or 17.7% lost neutralizing activity and another eight (4.6%) already had antibodies.
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A shorter three-month follow-up exercise of 607 of the 1058 found that only 5.6% lost their neutralizing activity and that only 2.8% no longer had antibodies.
The study was conducted in the Phenome India cohort which includes permanent staff, their relatives, students and temporary employees who provide support services to CSIR laboratories in 17 states and union territories.
“Widespread asymptomatic SARS-CoV2 infections affected nearly 100 million Indians in September 2020, with a subsequent decline in new cases that can be attributed to increased population immunity, although reduced the neutralization activity at six months may make this respite temporary, ”the study’s impact statement reads.