The pandemic has claimed over seven million lives officially, but the actual death toll is believed to be much higher. Among COVID-19 survivors, a significant number develop long-term health problems. The World Health Organization uses the term Long COVID for individuals experiencing such symptoms for over three months without another explanation.
Unfortunately, measuring chronic illness and disability resulting from COVID-19 has been challenging due to various factors. While binary outcomes like deaths and ICU admissions are easily counted, tracking slow-onset health issues is more difficult. This is further complicated by the fact that new health problems can arise even without SARS-CoV-2 infection. Consequently, studies utilising different methodologies have reported a wide range of Long COVID incidence rates. A recent study in JAMA Network Open has aimed to address this issue by comparing people who had COVID-19 with those who did not.
The researchers utilised the U.S. blood donor data from 2,38,828 individuals, leveraging antibody test results from the pre-Omicron era to identify individuals who had COVID-19. Specifically, they looked for the presence of anti-nucleocapsid (anti-N) antibodies, which indicates past natural infection. The advantage is that it also identifies people who had asymptomatic infection and those who were infected but did not get tested. The two COVID-19 vaccines used in the U.S. do not elicit the anti-N antibody, thus distinguishing natural infection from COVID-19 vaccination.
