. . "815" . . . . . . . . . . . . "1f09630649c6584bb2b34d55e282e31328fe466d" . . "Connecting clusters of COVID-19: an epidemiological and serological investigation" . . . . "20" . "20" . . . . "2020-07"^^ . . . . . . . "10.1016/s1473-3099(20)30273-5" . "10.1016/s1473-3099(20)30273-5" . . . . . . . "10.1016/s1473-3099(20)30273-5" . . "815" . . . . "809" . . . . "Elsevier BV" . . . "809" .