Factors associated with the opposition to COVID-19 vaccination certificates: a multi-country observational study from Asia by Kc, S, Faradiba, D, Sittimart, M, Isaranuwatchai, W, Ananthakrishnan, A, Rachatan, C, Dabak, S, Shafie, AA, Guerrero, AM, Suwantika, A, Kang, G, Ahn, J, Hsu, LY, Mayxay, M, Howard, N, Wattanasri, P, Nakamura, R, George, TK, Teerawattananon, Y