Wissa, who scored 20 goals for Brentford last season, returned from a knee injury to make his Newcastle debut as a late substitute in Saturday's Premier League win over Burnley, becoming the 1000th player to represent the club in a league fixture.
"He is ready to take on minutes. We have limited time between matches for him to get fitness, but in those 20 minutes he showed what he is capable of," Howe said ahead of Wednesday's Champions League clash at Bayer Leverkusen.
"However we get through, the knockout phase is the target. It would be preferable to go through without a playoff, but the teams we have to face are in good form."
Newcastle, who have nine points from five matches in the Champions League, are just a point below the top eight, who will qualify directly for the knockout stage. Teams who finish ninth to 24th in the league stage will enter a knockout playoff round to reach the last 16.
Howe's men are unbeaten in their last three matches, but their last Champions League outing ended in a 2-1 loss at Olympique de Marseille last month.
Leverkusen, who are a point below Newcastle, have triumphed in their last two Champions League matches, including a win at Manchester City.
"Leverkusen are an outstanding team, true to their identity, so this will be a tough game," Howe said.
"Any team that wins at Man City demands your attention... I have watched them in the Bundesliga, they are a very strong team, good at playing flexible systems which makes them difficult to play against."