Scientists from Washoe County, Nevada have just confirmed the first case if coronavirus reinfection in the United States. The 25-year-old patient is the fifth case of Covid-19 reinfection recorded around the world.
For months, researchers have been trying to understand how coronavirus affects the immune system and how the body builds resistance against its pathogens. Triggering antibodies to fight the virus has especially been crucial in vaccine developments.
The rare cases of reinfection raise a lot of questions about the immune system's response to the virus, especially with some vaccine developers promising protection for up to three years. The patient's case study was recently published in The Lancet journal describing reinfection after six weeks of his first infection.
His first nasopharyngeal swab test was taken on April 18, where he tested positive after having initial symptoms. The patient recovered by May and tested negative twice. On June 5, he tested positive again. Genomic analysis from both infections revealed that his second case was more severe than the first time he got infected.
Implications for Reinfection
In another study by Professor Akiko Iwasaki from Yale University School of Medicine, she wrote about what Covid-19 reinfection could mean. "For some viruses, the first infection can provide lifelong immunity; for seasonal coronaviruses, protective immunity is short-lived," she wrote.
Iwasaki also inquired that maybe reinfection occurs because the antibody response after the first infection was not enough. She also noted that this was the second case where the second reinfection was worse than the first. In September, an official case study described the genomic evidence of a patient from Ecuador that had worse reinfection in July compared to their initial infection in May.
Professor Iwasaki said that there are multiple reasons why a person may get sicker the second time. For example, the second time around, they could have been exposed to higher levels of the virus or the immune response from the initial infection made the disease worse.
It remains challenging for researchers to confirm if reinfection is as rare as the five reported cases or may be widespread. Scientists would need to have swab tests results from both times of infection to conduct a proper genomic analysis.
Moreover, only advanced hospitals can conduct genome sequencing. Experts speculate, therefore, that many reinfection cases remain undetected.
Chances of COVID-19 Reinfection
There also remains a lot of questions about asymptomatic cases and why the other three reported cases had milder reinfection. Professor Danny Altmann from Imperial College London said that so far, it seems that 90% of those with symptomatic infections may have sufficient antibodies to resist reinfection for about a year. It means that nearly 10% of symptomatic patients may lack antibodies and may be reinfected.
Professor Iwasaki remains hopeful over the vaccine candidates being developed since vaccines, especially those with adjuvants, "can induce much better immunity, a much longer-lasting immunity, than the natural exposure to the virus."
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