In light of the previous reports on pre-pandemic flavivirus serum showing cross-reactivity with SARS-CoV-2 S protein [18,19,21] and the predictions of shared epitopes on S-protein RBD and dengue E protein [20], the question was asked whether the detection of N-protein specific IgA or IgG, unrelated to the neutralizing antibodies against the S-protein target, is affected by the anti-dengue IgG present in Bangladeshi patients suffering from COVID-19 disease and having previous dengue infection. Here, PROS1 is linked to dengue disease.