Post-Exposure Prophylaxis Is the Missing Piece: Q&A with Florin Draica

While the general public may view the COVID-19 pandemic as a thing of the past, the virus continues to impact a significant number of people each year. Worse yet, many people who get sick with COVID find themselves facing long-term impacts, even after the initial sickness has passed.

Pharmaceutical Executive spoke with Florin Draica, senior vice president of US medical affairs at Shionogi, about the status of the disease and how new treatment methods are still being developed, such as XOCOVA. The FDA-approved medication is designed to be taken after exposure to the virus but before symptoms set in, in order to prevent serious illness.

Dr. Draica spoke about the ongoing impact of COVID, along with the industry’s broader need to start pursuing preventative medicines more often. By doing this, the public health playbook could focus on preventing illness while also treating people who still get sick.

Click here for the video version of this interview!

Pharmaceutical Executive: What is the importance of reframing COVID-19 as a preventable event?
Dr. Florin Draica: Let’s start by talking about where we are with COVID-19 today. We tend to look at the disease in retrospect and compare it to what it was in 2020 or 2021 — and we are well beyond that phase. But it is important to recognize that COVID-19 continues to affect millions of Americans every year.

People are still being hospitalized, and an increasingly important area of emerging evidence involves the lasting impact of COVID-19 beyond the initial infection. Multiple studies have shown that people diagnosed with COVID-19 experience increased rates of new-onset conditions, or worsening of existing conditions, across neurologic, cardiovascular, respiratory, and chronic kidney disease categories — and this persists throughout the year following infection.

COVID-19 activity also continues to rise during predictable periods, including summer and winter. The disease remains highly transmissible: up to approximately half of people living with an infected individual will go on to develop COVID-19 themselves.

While vaccination remains critical for prevention, it does not always prevent infection completely. Vaccine effectiveness is also reduced in people with certain conditions, particularly those with impaired immunity, and protection wanes over time.

This creates an important gap — the window between the moment someone is exposed to an infected person and the point at which they develop symptoms. That post-exposure window is where post-exposure prophylaxis comes in, and it is where XOCOVA can play a role in helping to prevent COVID-19 from developing in the first place.

PE: How do medications like XOCOVA prevent illness after exposure to COVID-19?
Draica: XOCOVA, which contains citalopram, is a protease inhibitor antiviral. After someone is exposed to COVID-19, the virus begins to replicate and multiply very rapidly — often before symptoms appear. That period between exposure and symptom onset, known as the incubation period, is critical. Acting quickly during this window can help reduce the risk of developing symptomatic COVID-19.

XOCOVA offers a new approach to prevention by blocking SARS-CoV-2 replication in that critical window between exposure and symptom onset. It does this regardless of a person’s prior infection history, vaccination status, or individual risk profile. XOCOVA should be taken as soon as possible and within three days of exposure to a person with COVID-19.

A few important points about our clinical evidence. In the SCORPIO-PEP trial, we did exclude participants who had been vaccinated within the prior six months. However, 70% of participants had received a COVID-19 vaccine at some point. We assessed antibody levels against the nucleocapsid and spike proteins of SARS-CoV-2, and found that virtually all participants — 98% — had detectable antibodies, indicating evidence of prior infection, prior vaccination, or both.

This is an important finding: XOCOVA works even in people who have prior immunity from vaccination or previous infection.

In terms of outcomes, even with the majority of participants demonstrating baseline immunity, XOCOVA demonstrated a 67% reduction in the proportion of household contacts who developed symptomatic COVID-19 compared to placebo through day 10.

PE: Should there be more of a focus on developing preventative medications?
Draica: The short answer is a resounding yes. Infectious diseases spread, and the earlier you can intervene — at the onset of an outbreak, immediately following exposure, or even before exposure through pre-exposure prophylaxis — the greater the public health impact.

I would start by saying that testing is foundational. You need to know when an outbreak is occurring in order to respond to it. From there, preventative antivirals become essential — to limit spread, to stop transmission early, and where infection has already occurred, to treat. The role of prevention is critical, and it is something Shionogi has recognized for a long time.

We have a longstanding heritage in anti-infectives. One of the antivirals that set a landmark in how HIV is managed was developed by Shionogi. We also developed an influenza antiviral that is used both for treatment and prevention. We brought that same philosophy to COVID-19 with XOCOVA.

While treatment options exist — and ensitrelvir, the active compound in XOCOVA, is approved for treatment in Japan and other countries — we specifically focused on post-exposure prophylaxis, recognizing that there was an unaddressed gap in that window after someone is exposed to COVID-19 and before symptom onset. That is the space XOCOVA is designed to address.

PE: How might preventative medications impact the lingering impact of COVID-19?
Draica: COVID-19 continues to affect millions of people in the United States and worldwide. One thing worth noting is that we tend to assess its impact by comparing it to the pandemic years — and I think that framing is not entirely accurate.

Even mild to moderate COVID-19 infection can have a genuinely damaging impact on people with chronic underlying conditions. Consider a patient with COPD or asthma: even a mild case of COVID-19 can trigger an exacerbation. The same is true for patients with chronic kidney disease, neurological conditions, or cardiovascular disease. COVID-19 can disrupt the fragile balance of disease management in these populations in ways that extend well beyond the acute phase.

That worsening does not always happen immediately. It does not always show up in the first two weeks, or even the first month. We are seeing a growing body of studies showing detrimental impacts from exacerbation of underlying health conditions at six months, and even up to a year after the acute infection. The damage may be more lasting than acute hospitalization data alone would suggest. Hospitalizations from acute COVID-19 have certainly decreased compared to the pandemic — but we are increasingly recognizing a category of lasting harm that is harder to observe in the short term.

This matters especially because many Americans carry multiple risk conditions simultaneously. Someone with chronic kidney disease who also has diabetes faces a cumulative risk profile. The concern is not just what happens during the acute infection — it is what may be triggered over the longer term.

For all of these reasons, testing and exposure notification remain critically important. When someone tests positive, informing the people they have recently been in contact with — a phone call, a message, a simple heads-up — gives those individuals the opportunity to act. And today, with ensitrelvir and XOCOVA available, exposed individuals have the option to prevent COVID-19 from developing altogether, if they take the antiviral within three days of exposure.