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By E.J. Mundell<\/b>
HealthDay Reporter<\/i><\/p>\n
WEDNESDAY, July 22, 2020 (HealthDay News)<\/p>\n
Hopes for robust, long-term antibody protection after a bout of COVID-19<\/a> have been dampened by a new study that finds the protection may only last a few months.<\/p>\n Still, experts noted that the body’s immune system has more than one way to defend against viruses<\/a> it has already encountered, so the findings don’t dash hopes for a vaccine<\/a>.<\/p>\n “Infection with this coronavirus does not necessarily generate lifetime immunity,” Dr. Buddy Creech, an infectious disease specialist at Vanderbilt University in Nashville, told the Associated Press<\/i>.<\/p>\n But antibodies are only part of the immune system’s armamentarium, added Creech, who wasn’t part of the new research.<\/p>\n The study was published July 21 in the New England Journal of Medicine<\/i>. Researchers led by Dr. Otto Yang, of the University of California, Los Angeles, sought to determine the “half-life” of antibodies generated by contact with the new SARS<\/a>-CoV-2 virus. Half-life means the time it takes for half of the antibodies to disappear.<\/p>\n Yang’s group took blood samples from 34 people who had all recovered from a mild case of COVID-19<\/a>. Twenty were women and 14 were men, and they averaged 43 years of age.<\/p>\n Based on blood tests collected up to 119 days after the onset of symptoms, the researchers said the half-life of antibodies linked with SARS<\/a>-CoV-2 infection was just 36 days — just over a month. At that rate, antibodies would disappear completely in about a year.<\/p>\n It’s an “antibody loss [rate] that was quicker than that reported for SARS<\/a>-CoV-1,” the coronavirus responsible for the 2003 SARS<\/a> outbreak, the researchers noted.<\/p>\n “Our findings raise concern that humoral [found in body fluids] immunity against SARS-CoV-2 may not be long lasting in persons with mild illness, who compose the majority of people with COVID-19<\/a>,” they said.<\/p>\n “Like the common cold<\/a>-causing coronaviruses, the new coronavirus does not appear to provide durable antibody-based immunity for a long period of time,” said Dr. Amesh Adalja, a senior scholar with the Johns Hopkins Center for Health Security in Baltimore.<\/p>\n But that doesn’t mean that immunity necessarily is gone, he added, since the human immune system has other tricks up its sleeve.<\/p>\n “It still remains to be seen whether these individuals can be reinfected and, if so, what that clinical course is like, as T-cell immunity is also an important factor to consider,” said Adalja, who wasn’t involved in the new study.<\/p>\n T-cells are a distinct component of what’s known as the adaptive immune system. They help fight infection in many ways, including directly killing infected cells.<\/p>\n For his part, Creech agreed that just because antibodies to SARS-CoV-2 have a relatively short half-life doesn’t mean people lose the ability to fight off recurrent infection.<\/p>\n He explained to the AP<\/i> that antibodies are proteins produced by immune system B cells to help recognize and destroy cells infected with a virus. When a new virus is first encountered, more generalized forms of antibodies are quickly produced, but their specificity against the virus gets increasingly precise as time goes on.<\/p>\n The B cells also develop a kind of memory as to how to generate these precise antibodies if the virus appears in the body again.<\/p>\n “They would get called into action very quickly when there’s a new exposure to the virus. It’s as if they lie dormant, just waiting,” Creech said. T-cells also lie in wait, able to mount a separate battle against infected cells, he said.<\/p>\n And what about hopes for a vaccine<\/a>?<\/p>\n Efforts to find an effective vaccine are still valid, Creech said, because a vaccine’s highly targeted approach against viruses<\/a> actually exceeds that of the natural immune system.<\/p>\n “This shouldn’t dissuade us from pursuing a vaccine,” Creech said. “Antibodies are only a part of the story.”<\/p>\n <\/p><\/div>\n![\"MedicalNews\"](\"https:\/\/images.medicinenet.com\/images\/HealthDay\/healthday.png\")
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