Lord Coe admits these are "dark days" for athletics but has stressed his determination to lead the sport down the "long road to redemption".
It emerged on Friday that the International Association of Athletics Federations (IAAF) ethics commission had brought disciplinary charges against four men, including the son of former president Lamine Diack and the former head of its anti-doping department, amid the corruption crisis engulfing international athletics.
French police had already revealed Diack, who was succeeded as head of the IAAF by Coe at the end of August, was being investigated over an alleged payment of more than €1 million (£713,800, $1.07m) to cover up doping offences by Russian athletes.
Asked on Sunday for his reaction to those developments, Coe told BBC Radio Five Live's Sportsweek programme: "Clear shock, a great deal of anger and a lot of sadness.
"These are dark days for our sport but I'm more determined than ever to rebuild the trust in our sport. It is not going to be a short journey.
"The day after I got elected, I started a massive review. Understandably, in the light of the allegations that have been made, that review has been accelerated and I am determined to rebuild and repair the sport with my colleagues. But this is a long road to redemption."
Coe, who insisted he was not aware of any allegations against Diack until this week's news, said when asked if he thought the situation would be shown to involve nations other than Russia: "We'll have to wait for the basis of the WADA report tomorrow. It will be interesting to see where they think that scope is.
"We do know we are taking a disproportionate amount of damage from a relatively few number of nations out there. The answer is we will wait - I don't know. It may well."
Richard McLaren, one of the authors of the report, has been quoted as saying that it will be "a real game-changer for sport" and that "a whole different scale of corruption" even compared to the FIFA scandal will be shown.
When it was put to WADA president Sir Craig Reedie on Sportsweek that the report was likely to cause shock, he said: "I think there's been a great deal of speculation.
"I think it will be very robust in terms of what it was set up to do, which was to examine serious breaches of doping rules in Russia, and the anti-doping community and sport should be ready for that."
"I am more determined than ever to rebuild this sport and restore trust"— Seb Coe (@sebcoe) November 8, 2015
There has been talk of the possibility of Russia being thrown out of the sport. And Coe said on that matter on Sunday: "I've never said never, but my instinct here is engagement rather than isolation.
"If we want change, and this is not just about processes and procedure, it is cultural. We need a generation of athletes and coaches who believe it is absolutely possible to reach the pinnacle of our sport and do it with integrity, as clean athletes.
"I believe isolation is not the answer, and that engagement is a much better way to get internal change. But I am not saying, and never have said, never."
He added: "Will we ever have a clean sport? No. The practicality is simple. There will always be people in any walk of life who will step beyond the moral boundaries.
"It is our responsibility to make sure we have the right systems in place -- and the right people in the organisation upholding those systems."
Coe was also asked if he regretted referring to Diack as the sport's "spiritual leader" when he succeeded him. "I'm well aware I'm going to come in for criticism for those remarks," Coe said.
"It does presume I had a list of allegations in front of me at that moment, and I didn't. Should we, in hindsight, have known more? Yes, probably we should have done -- that is why I have accelerated these reforms at breakneck pace this week."