. g4 b7 b# O6 y/ r; g6 |Scientists are concerned that measures to combat Covid-19 have weakened the immune systems of young children who have not been able to build up resistance to common bugs, leaving them vulnerable when mask-wearing and social distancing eventually end.. g2 ]% e2 n- a https://www.theguardian.com/soci ... -system-experts-say 7 C7 p: I( x/ D' U. ]Lockdown最受害的是儿童。