Long-term humoral immune response in persons with asymptomatic or mild SARS-CoV-2 infection, Vietnam by Mai, HK, Trieu, NB, Long, TH, Thanh, HT, Luong, ND, Huy, LX, Nguyet, LA, Man, DNH, Anderson, DE, Thanh, TT, Chau, NVV, Thwaites, G, Wang, L-F, Van Tan, L, Hung, DT, Furse, R