Elsevier established a free COVID-19 resource centre in January 2020, offering information in English and Mandarin. The centre grants permission for free access to its research in PubMed Central and other repositories. The article reviews chloroquine's effects on viral infections, highlighting its antiviral and immunomodulatory properties. Chloroquine, a 9-aminoquinoline, inhibits viral replication by affecting endosomal pH and has been studied for its potential in treating HIV and SARS. It suppresses pro-inflammatory cytokines like TNFα and IL-6, which are involved in viral disease complications. Chloroquine's ability to inhibit viral entry and replication, particularly in enveloped viruses, is discussed, along with its potential in combination therapies with other antiretrovirals. The drug's safety profile is noted, with manageable toxicity and a history of use in malaria and autoimmune diseases. Chloroquine may also help in preventing mother-to-child HIV transmission through breastfeeding. The article suggests that chloroquine could be useful in treating HIV and SARS due to its antiviral and anti-inflammatory effects, though further clinical trials are needed to confirm its efficacy. The study also highlights chloroquine's potential in treating other viral infections involving immune activation. The review concludes that chloroquine, despite being an old drug, may have a role in modern viral disease management.Elsevier established a free COVID-19 resource centre in January 2020, offering information in English and Mandarin. The centre grants permission for free access to its research in PubMed Central and other repositories. The article reviews chloroquine's effects on viral infections, highlighting its antiviral and immunomodulatory properties. Chloroquine, a 9-aminoquinoline, inhibits viral replication by affecting endosomal pH and has been studied for its potential in treating HIV and SARS. It suppresses pro-inflammatory cytokines like TNFα and IL-6, which are involved in viral disease complications. Chloroquine's ability to inhibit viral entry and replication, particularly in enveloped viruses, is discussed, along with its potential in combination therapies with other antiretrovirals. The drug's safety profile is noted, with manageable toxicity and a history of use in malaria and autoimmune diseases. Chloroquine may also help in preventing mother-to-child HIV transmission through breastfeeding. The article suggests that chloroquine could be useful in treating HIV and SARS due to its antiviral and anti-inflammatory effects, though further clinical trials are needed to confirm its efficacy. The study also highlights chloroquine's potential in treating other viral infections involving immune activation. The review concludes that chloroquine, despite being an old drug, may have a role in modern viral disease management.