New research has emerged suggesting that Covid-19 antibodies may deplete faster than expected or hoped. Bluntly put, scientific assessments of the life cycle (the ability to provide immunity and for how long) of antibodies produced by an infected person is shorter than anticipated.
Antibodies are a protective protein produced by the immune system in response to the presence of a foreign substance within the body. These substances, also known as, antigens, can be bacteria, viruses, or any element the body does not recognize.
According to a study published in the online journal of Nature Medicine (June 18), Scientists have found that antibodies against Covid-19 begin to decrease within two to three months after the host’s recovery from the initial infection.
The conclusions are derived from studies conducted on both symptomatic and asymptomatic people with Covid-19. Eight weeks after recovery, antibody levels dropped to undetectable levels in 40% of those who did not exhibit symptoms and 13% of people who reported symptoms.
These are disconcerting findings. Covid-19 is a pneumonia-like virus that causes mild to severe respiratory illness. Most people infected with Covid-19 usually experience mild to moderate respiratory illness.
Greater complications arise in the elderly and people with underlying medical conditions. Such cases can develop into serious illness and could prove fatal. The rate of fatality among those living in long term care (LTC) facilities in Canada is a case in point. Of the 8,885 deaths attributable to Covid-19 (July 26), over 80% of fatalities occurred in LTC homes.
The New England Journal of Medicine, July 21, corroborated the conclusions. Its authors, American researchers from L.A. California, noted that while the protective role of antibodies against coronavirus is not known, such antibodies do offer partial anti-viral immunity - for some time.
The report confirms the antibody levels against Covid-19 decrease by about half, 36 days after infection. This is a shorter time frame than the previous study that showed levels began to decrease within two to three months.
Results from the latest studies show findings that people with mild illness may not have long-lasting immunity to Covid-19. Such discoveries further dampen the idea of “immunity passports”. Some governments have considered allowing recovered Covid-19 patients the option of returning to work or to travel under the presumption that they are immune from infection.
Moreover, short-lived levels of antibodies in asymptomatic infections further cast doubts on the effectiveness of “herd immunity”. More studies are needed as there remains no proven effective drug nor therapy to treat covid-19.
As a result, there is increased pressure on vaccine development. According to the World Health Organization, there are over 140 vaccine candidates in preclinical evaluation and 25 candidate vaccines in clinical evaluation and human trials. Antibodies are just part of the equation – a temporary one.
Currently the best protection consists of avoiding the contagion. Hence, be serious about social distancing, proper hygiene, public health directives, widespread testing, and isolation of those infected from those most vulnerable.
Be wise. Stay safe.