In the same week that an as-yet-peer-reviewed paper found that people infected with Covid-19 may be immune for years or more, the CDC published another study that found it may not Case is.
The CDC study, published in the November 27th issue of the agency’s weekly report on morbidity and mortality (MMWR), found that out of 156 healthcare workers who tested positive for Covid-19 this past spring, 146 (93.6%) had a decrease in coronavirus antibody levels when retested 60 days later.
Another 44 (28.2%) people had no detectable antibody levels. SARS-CoV-2 Antibody Decline After Mild Infection Among Frontline Healthcare Workers In A Tiered Hospital Network – 12 States, April – August 2020 | MMWR (cdc.gov) The CDC study said its results have implications for treatment with Covid-19, particularly those using convalescent plasma.
“These results show that the optimal window for the collection of convalescent plasma with high SARS-CoV-2 antibodies from donors who have recovered from Covid-19 may be short within 60 days due to the significant drop in antibody levels,” it says in the report. “It is unknown whether a decrease in SARS-CoV-2 antibodies increases the risk of re-infection and disease in humans.”
The study notes that while antibodies decrease or go undetectable over time, memory B-cell and T-cell responses may decrease the severity of the condition with repeated exposure or infection.
B cells and T cells are lymphocytes. B cells fight bacteria and viruses. There are two main types of T cells: helper T cells and killer T cells. Helper T cells stimulate B cells to make antibodies and help develop killer cells. Killer T cells eliminate cells that have been infected by a foreign invader. Introduction to T and B Lymphocytes – Autoimmunity – NCBI Bookshelf (nih.gov)
Another, not yet published study, however, showed a more hopeful view of the longevity of Covid-19 antibodies. Published online at bioRxiv, it found that people who have recovered from Covid-19 still have enough immune cells to fight off the virus and prevent re-infection eight months after being infected. Immunological memory against SARS-CoV-2 examined more than six months after infection bioRxiv
The study reported that people who have recovered from Covid-19 have antibodies and neutralizing plasma, as well as virus-specific memory B and T cells that not only linger, but in some cases gain weight over three months after symptoms appeared .
“That amount of memory would likely prevent the vast majority of people from suffering from serious illness in the hospital for years,” said Dr. Shane Crotty, a virologist at the La Jolla Institute of Immunology who led the new study with the New York Times.
The bioRxiv study is in line with reports from other laboratories. A study published a week earlier in the journal Nature Medicine found that people who had recovered from Covid-19 wore protective killer immune cells. Characterization of pre-existing and induced SARS-CoV-2-specific CD8 + T cells Natural medicine researchers at the University of Washington under the direction of immunologist Marion Pepper, PhD, had previously shown that certain “memory cells”, which were infected with the coronavirus According to the New York Times, they will persist for at least three months.
These studies “by and large all paint the same picture – that is, by the time you are through the first few critical weeks the rest of the response looks pretty conventional,” said Dr. Deepta Bhattacharya, an immunologist at the University of Arizona. told the New York Times. Immunity to Coronavirus Last May, New Data Advice – The New York Times (nytimes.com)
The positive response to the unpublished study came from around the world, showing how hungry scientists, doctors, and everyone in general, are for good news about the pandemic.
“This preprint has yet to be examined by experts, but it brings exciting news,” wrote Dr. Deborah Dunn-Walters, Professor of Immunology at the University of Surrey in London and Chair of the British Society for Immunology’s Expert Group on Immunology and Covid-19.
Robert Calandra is an award-winning journalist and author who has written extensively on health and medicine. His work has been published in national and regional magazines and newspapers.