Of course there should be concern for those already using these meds, but this is a 70 yr old drug, well off patent, where production can easily be ramped up. We've literally had millions and millions of pills donated for these tests being done. That doesn't happen when a drug is in short supply.

From an email I got the other day from the Lupus Foundation of America:

"Is a shortage of hydroxychloroquine (Plaquenil) expected?
Answer: The Food and Drug Administration (FDA) has posted a notice of a shortage of hydroxychloroquine. It is not possible to predict the full scope and duration of the shortage or the long term impact the coronavirus pandemic will have on the supply of hydroxychloroquine. We are actively working with all relevant stakeholders, including

our medical and scientific advisors,
other patient groups,
federal and state officials,
manufacturers of hydroxychloroquine and chloroquine,
state boards of pharmacy,
health plans,
pharmacies and pharmacists, and
physicians.

All of these groups can play a role in helping to ensure that people with lupus have access to the medications they need. Several manufacturers of hydroxychloroquine and chloroquine that we have reached out to have publicly announced they are increasing drug supplies or committing to donate the medications to the federal government in order to increase their supply and availability."