Can hydroxychloroquine prevent infection after exposure to coronavirus (COVID-19)?

Study looks at using drug to prevent infection from developing

DETROIT – Study into hydroxychloroquine as a treatment for the coronavirus (COVID-19) has constantly evolved throughout the pandemic, and now, researchers are studying whether the drug can prevent the infection from developing in someone who was exposed to the virus.

RECENTLY: New COVID-19 studies raise flags, under audit

Previously published studies have primarily focused on using hydroxychloroquine to treat COVID-19 after someone had already developed the infection, and to date, they have not been conclusive regarding benefit.

A new study moved up the process and examined whether hydroxychloroquine can prevent an infection after someone is exposed.

Study details

The randomized, double blind, placebo-controlled study was published in the New England Journal of Medicine by researchers from the University of Minnesota. It enrolled 821 people with a high or moderate risk of exposure to someone with COVID-19.

A high-risk exposure was defined as being within six feet of someone with COVID-19 for more than 10 minutes without a mask or eye protection.

Two-third of the participants were health care workers, mainly with occupational exposures. The remaining participants were mainly household contacts of COVID-19 patients.

Participants were provided with either hydroxychloroquine or placebo within four days of exposure and before any symptoms developed.


In the end, there was no significant difference in the number of COVID-19 infections after exposure, and it was concluded that hydroxychloroquine was not found to have a benefit in preventing the development of COVID-19 after exposure.

Notably, although no serious adverse reactions were seen, 40% of the people receiving hydroxychloroquine reported side effects, compared to 17% who received placebo.

Henry Ford Hospital is still enrolling for the WHIP COVID-19 study of front line workers. It is a much larger study asking a different question: “Can hydroxychloroquine help if used before exposure?” Dr. Frank McGeorge is involved in the study and took his last pill of the eight-week study on Thursday.

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