Quicksilver did not have a Kryptonian's array of Super Senses, so he had no idea what was happening elsewhere in the police station and naturally had no way to step in and stop it.
Although Henry had a good relationship with the NYPD and had deliberately tried to win them over, he was not at the point of shielding them from disaster unconditionally. Besides, no one had died today. A group of people had merely been bitten by Vampires, with a fairly high chance of being transformed.
Thinking back to the Reaper Vampires chaos in 2002, the police had also been mobilized and given countermeasures. Though he did not know who had supplied them, they should have included UV Bullets and Reaper Serum, though likely not in large quantities.
The new Reaper Vampires were immune to silver, so the bullets the police had received probably did not include Silver Nitrate Bullets, which had a relatively long shelf life. UV Bullets could not be preserved for two years, and even if that batch of bullets had been kept until now, they had probably already failed.
Reaper Serum was different from First Embrace Serum, which was meant for ordinary Vampire bites. Even if that old batch of serum still retained its effectiveness, it could not be injected carelessly into these bitten officers.
More importantly, those Vampires who had once provoked Gwen and the others should have come from Europe. Without samples for reference, Henry could not say for certain that the First Embrace Serum developed earlier could still cure these bitten officers.
From the Vampires' perspective, rather than threatening the rulers of the human camp and forcing them to submit to Vampires, it was better to transform them into their own kind.
Even if those newly born bloodkin hated the Vampire who