The DR Congo international completed a deadline-day move from Brentford earlier this season but has yet to feature for the Magpies after sustaining the injury on September 9 during a 2026 FIFA World Cup qualifier against Senegal.
Wissa was assessed by a specialist before Newcastle's clash with Nottingham Forest on October 5, and initial hopes of a quick return were soon dismissed. Howe later conceded that the 29-year-old forward would be out for "slightly longer" than first anticipated, having previously been tipped to return in time for the trip to Brighton on October 18, according to Africanfootball.com.
Speaking ahead of Saturday's Premier League fixture against West Ham United, Howe admitted that there remains no clear timeline for Wissa's return to full fitness.
"Definitely not West Ham," Howe said when asked if the forward could feature this weekend.
"He's working very hard and is out on the grass, but he's still not close to training with the group — not because of a new injury, but due to fitness levels.
"I'm not trying to be evasive, but I genuinely don't know when he'll be back with the squad," the Newcastle boss added.
Wissa's absence has left Newcastle short of attacking options, though Howe remains hopeful the former Brentford star will make an impact once fully fit later in the campaign.
Mikel Arteta has admitted Arsenal must remain grounded despite their stunning start to the season, as the Gunners continue to battle on multiple fronts at home and in Europe.
Tottenham manager Thomas Frank has eased fears over injuries to Mohammed Kudus and Djed Spence ahead of Tuesday's crucial Champions League clash with Copenhagen.
Liverpool manager Arne Slot has backed Florian Wirtz to come good despite the German midfielder's difficult start to life at Anfield.
Regis Le Bris has praised Sunderland's determination after they battled back to earn a 1-1 draw with Everton in the Premier League at the Stadium of Light on Monday night.
