I don’t believe there exists any remotely reliable correlation between Ct values and time of infection, especially for a single random patient and over the purported timescale (>4 months, assuming the infection happened outside Taiwan as stated). As in, I’m very skeptical that it’s possible for them to judge with any confidence that the infection happened outside Taiwan from a high Ct value (36, apparently?).
莊人祥說，由於個案次日再驗核酸結果為陰性，血清抗體IgM及IgG皆為陽性，推測感染時間已久，研判於美國期間遭感染的機會較高；已初步掌握個案接觸者10人，1人為同住者，列居家隔離，9人為非同住親友，列自主健康管理；10名接觸者中，7人已採檢核酸及血清抗體，其中4人核酸及血清抗體檢驗皆為陰性、其餘檢驗中，3人待採檢。
Does this mean that after the initial positive PCR test on March 23 he tested negative in a subsequent PCR test (and positive for antibodies)? I’d be more inclined to suspect a testing issue there (i.e., either a false positive, the threshold used is too low, or it took a (very) abnormal amount of time for his body to clear the RNA while he remained fine and asymptomatic)…it seems dubious to me whether this should be considered a “case” at all from this information.
Of course, if they’re just assuming that the infection couldn’t possibly have happened in Taiwan then it follows that they could logically assign this as an “imported case”, subject to the assumption being correct, given that those are the only two options. 