(ShareCast News) - Shares in Cello Health fell after the company issued a half year profit warning.At 0917 BST shares in the healthcare marketing firm had fallen 3.69% to 97.75p.The company said in its half year update to 30 June 2015 that profits would be lower to its due to lower profits at its consumer division Signal, which had increased its headcount.Cello said it was confident full year expectations would be met.The company had settled a VAT tax issue which meant it did not have to alter its current provisions.N+1 Singer remained bullish on the stock and reiterated a 'buy' rating."Cello has been building a good record of delivery and today's update continues this," N+ 1 Singer said in a note.