Human seasonal coronavirus neutralization and COVID-19 severity

The virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for the global coronavirus disease-2019 (COVID-19) pandemic, spread rapidly around the world causing high morbidity and mortality. However, there are four known, endemic seasonal coronaviruses in humans (HCoVs), and whether antibodies for these HCoVs play a role in severity of COVID-19 disease has generated a lot of interest. Of these seasonal viruses NL63 is of particular interest as it uses the same cell entry receptor as SARS-CoV-2. We use functional, neutralizing assays to investigate cross-reactive antibodies and their relationship with COVID-19 severity. We analyzed the neutralization of SARS-CoV-2, NL63, HKU1, and 229E in 38 COVID-19 patients and 62 healthcare workers, and a further 182 samples to specifically study the relationship between SARS-CoV-2 and NL63. We found that although HCoV neutralization was very common there was little evidence that these antibodies neutralized SARS-CoV-2. Despite no evidence in cross-neutralization, levels of NL63 neutralizing antibodies become elevated after exposure to SARS-CoV-2 through infection or following vaccination.