Harvard Cov Lus Qhia Txog Kev Lag Luam: Kwv yees li 4 lab teev nyob rau ib hnub hauv UK yog siv hauv kev sib tham hauv pab pawg, hauv Tebchaws Meskas, nruab nrab 1,100 pawg rooj sib tham hauv ib hnub, txhua qhov yog 3.5 teev hauv ib hnub, tsis yog 1 teev.