Coronavirus disease 2019

COVID-19 is a con­ta­gio­us dise­ase cau­sed by the coro­na­vi­rus SARS-CoV-2. In Janu­ary 2020, the dise­ase spre­ad worl­dwi­de, resul­ting in the COVID-19 pan­de­mic.

The symp­toms of COVID‑19 can vary but often inc­lu­de fever,[7] fati­gue, cough, bre­athing dif­fi­cul­ties, loss of smell, and loss of taste.[8][9][10] Symp­toms may begin one to four­te­en days after expo­su­re to the virus. At least a third of people who are infec­ted do not deve­lop noti­ce­able symptoms.[11][12] Of tho­se who deve­lop symp­toms noti­ce­able eno­ugh to be clas­si­fied as patients, most (81%) deve­lop mild to mode­ra­te symp­toms (up to mild pneu­mo­nia), whi­le 14% deve­lop seve­re symp­toms (dys­p­nea, hypo­xia, or more than 50% lung invo­lve­ment on ima­ging), and 5% deve­lop cri­ti­cal symp­toms (respi­ra­to­ry failu­re, shock, or mul­tior­gan dysfunction).[13] Older people have a higher risk of deve­lo­ping seve­re symp­toms. Some com­pli­ca­tions result in death. Some people con­ti­nue to expe­rien­ce a ran­ge of effects (long COVID) for mon­ths or years after infec­tion, and dama­ge to organs has been observed.[14] Mul­ti-year stu­dies on the long-term effects are ongoing.[15]

COVID‑19 trans­mis­sion occurs when infec­tio­us par­tic­les are bre­athed in or come into con­tact with the eyes, nose, or mouth. The risk is highest when people are in clo­se pro­xi­mi­ty, but small air­bor­ne par­tic­les con­ta­ining the virus can rema­in suspen­ded in the air and tra­vel over lon­ger distan­ces, par­ti­cu­lar­ly indo­ors. Trans­mis­sion can also occur when people touch the­ir eyes, nose, or mouth after touching sur­fa­ces or objects that have been con­ta­mi­na­ted by the virus. People rema­in con­ta­gio­us for up to 20 days and can spre­ad the virus even if they do not deve­lop symptoms.[16]

Testing methods for COVID-19 to detect the virus’s nuc­le­ic acid inc­lu­de real-time rever­se trans­crip­tion poly­me­ra­se cha­in reac­tion (RT‑PCR),[17][18] trans­crip­tion-media­ted amplification,[17][18][19] and rever­se trans­crip­tion loop-media­ted iso­ther­mal ampli­fi­ca­tion (RT‑LAMP)[17][18] from a naso­pha­ryn­ge­al swab.[20]

Seve­ral COVID-19 vac­ci­nes have been appro­ved and distri­bu­ted in vario­us coun­tries, many of which have ini­tia­ted mass vac­ci­na­tion cam­pa­igns. Other pre­ven­ti­ve measu­res inc­lu­de phy­si­cal or social distan­cing, quaran­ti­ning, ven­ti­la­tion of indo­or spa­ces, use of face masks or cove­rings in public, cove­ring coughs and sne­ezes, hand washing, and keeping unwa­shed hands away from the face. Whi­le drugs have been deve­lo­ped to inhi­bit the virus, the pri­ma­ry tre­at­ment is still symp­to­ma­tic, mana­ging the dise­ase thro­ugh sup­por­ti­ve care, iso­la­tion, and expe­ri­men­tal measu­res.