Haruto was clearly about to panic. Issei felt like panicking himself, but as the older one, he needed to stay calm and keep his friend from becoming hysterical.

"So if you were home, and I was home, then - virus." Issei took a deep breath and offered Haruto a reassuring smile. "That must be it. I'm sure that the moment we check the community, we'll see tons of post complaining about waking up next to someone else. It's nothing to worry about."

...Still really embarrassing, but nothing to worry about.