Pre-Exposure Prophylaxis for COVID-19: Lessons From the Past and the Search for New Options

Pre-Exposure Prophylaxis for COVID-19 Lessons From the Past and the Search for New Options

A new pre-publication report, “Pre-Exposure Prophylaxis for COVID-19 Disease,” by Raphael Stricker, MD and Melissa Fesler, FNP-BC, offers a look at a front-end prevention strategy. With over five million people infected worldwide and over 345,000 deaths, economies are at a standstill and, “social isolation based on a palpable fear of death remains the order of the day.” Re-opening the nation would be much safer with a COVID-19 preventative, and this study looks at that prospect.

Past Malaria Treatment Offer Clues to Future Applications 

Traditionally prophylaxis for viruses has relied on vaccines. But this could take two years, and immediate interventions are needed. Pointing out that pre-exposure prophylaxis (PrEP) with anti-virals has been a viable tactic, it is also key to keep in mind the high-risk populations (aged, ill, etc.) who most need protection. Doctors also face exposure, so they could benefit from an interim prophylactic treatment. The most prominent candidate is the politically-loaded hydroxychloroquine (HCQ). The study offers that HCQ has an extremely long half-life of up to 40 days. This property has allowed it to be used weekly for malaria prophylaxis for several decades. They speculate about cross-immunity, “Malaria prophylaxis with HCQ may also contribute in part to the reportedly low rate of COVID-19 disease seen so far in sub-Saharan Africa.”

The authors propose instituting a regimen of 400mg of HCQ weekly in high-risk patients based on past malaria-prevention protocols. The “regimen will allow individuals to resume work with some modicum of protection against COVID-19 disease.” And, although, “a higher-dose regimen might be more effective, higher dosing would also increase the risk of adverse events without clear benefit at this point in the pandemic.” 

Hydroxychloroquine Alternatives

Addressing the ongoing HCQ controversies, Stricker and Fesler note that, “mefloquine 250mg could be used instead. This oral medication has a half-life of about three weeks and appears to be active against SARS-CoV-2 in vitro, which makes it suitable for weekly antiviral prophylaxis.” Mefloquine, unfortunately, has negative neuropsychiatric effects making it “less attractive.” Another option is “the antiparasitic drug ivermectin. This antimicrobial agent with antiviral properties appears to be effective against SARS-CoV-2 in vitro and in vivo.”   

In closing, the authors state that more results for HCQ prophylaxis will be available in coming months. They argue that until a vaccine is found, PrEP “seems a logical and feasible choice for resumption of work activities and social interaction on a worldwide scale.”

TrialSite News will continue to follow the HCQ saga and PrEP applications in the pre-vaccine era.