Antibodies suggest that people who already have COVID-19 may be protected from reinfection for at least some time
Researchers tested and tracked 12,541 healthcare workers for up to 31 weeks at Oxford University Hospital in the United Kingdom. Polymerase chain reaction (PCR) tests were performed on healthcare professionals who tested positive and negative, including both symptomatic and asymptomatic cases, to determine the incidence of COVID-19. ..
Of the 12,541 healthcare professionals, 11,364 had no antibody levels and 1,265 tested positive. This includes 88 healthcare professionals who experienced seroconversion during follow-up. 223 spike-negative healthcare workers tested positive for PCR. Up to 100 were asymptomatic and 123 were symptomatic.
Studies published in the journal Scientific immunochemistry Patients were followed from day 4 to day 242 after infection. All of these patients had memory B cells that “remembered” the viral protein and could activate rapid antibody production when re-exposed to the virus until eight months after the initial infection.
By 6 days after infection, all patients showed immunoglobulin (Ig) G antibodies to the viral receptor binding domain, and these IgG levels began to decline 20 days after the onset of symptoms.
In contrast, memory B cell levels continued to rise up to 150 days after infection and remained detectable 240 days after the onset of symptoms. This suggests that the patient’s immune system is ready to respond to reinfection. Long-term presence is a better indicator of a long-term immune response than serum antibodies.
The authors state that cell-mediated immunity may explain why there are few recorded cases of reinfection with SARS-CoV-2.
Dr. Menno van Zelm, Senior Author of Monash University, said: “These results are important because they clearly show that patients infected with the COVID-19 virus actually have immunity to the virus and the disease. This may be provided by COVID. There is a black cloud of potential protection. -19 vaccines, and when one or more vaccines are developed, they give real hope that they will provide long-term protection. “
Studies published in the journal Emerging infectious diseases We investigated the antibody response of 58 COVID-19 patients confirmed in South Korea 8 months after asymptomatic or mild SARS-CoV-2 infection and found a high proportion of serum antibodies.
Researchers used four commercially available immunoassay tests to measure COVID-19-specific antibodies in patients isolated at the Regional Treatment Center at Seoul National University Hospital.
The author said, “We explain the differences in rates between studies because rates vary by immunoassay method and manufacturer. There are concerns about weakened immunity, but with proper immunoassays, most asymptomatic or mild symptoms are present. Antibodies to SARS-CoV-2 can be detected 8 months after infection in humans. “