I'm seeing (too) many reports of "Infected people who recovered are testing positive again!!" My take as a molecular biologist:

The fact that the world was poorly prepared for a #pandemic of this type doesn't make COV-2 uniquely different from all other viruses. 1/3 #COVID19

Everyone infected will mount an #antibody response, aka various degrees of #immunity. The 2-10% re-infection may be due to: inaccurate tests; insufficient antibody levels for secondary defense; permanent viral reservoirs in recovered individuals (à la Herpes or Hepatitis); 2/3

[ctd] rapid mutation (a well-known attribute of all RNA viruses). What's problematic is the haste of governments to issue "clean health" certificates to clear people for work or travel. It won't work as they (like to) think. A flu-type #vaccine is the only real solution. 3/3