Pfizer reported lower third-quarter profits Tuesday as Covid-19 dented demand for some medicines from patients whose regular health care patterns were disrupted.The drug maker, which is working on clinical trials for a coronavirus vaccine, reported a 71 percent drop in profit to $2.2 billion. The year-ago period included a large gain connected to a transaction.Revenues dipped four percent to $12.1 billion, missing analyst estimates.Pfizer estimated a revenue hit of $500 million connected to Covid-19 due to lower pharma demand in China and fewer wellness visits from patients in the US.The company saw an 11 percent drop in its hospital business in emerging markets, primarily due to fewer elective surgeries in China and shorter in-patient hospital stays in the country.This effect was partially offset by increased demand for the Prevnar-13 vaccine for pneumonia “resulting from greater vaccine awareness for respiratory illnesses,” the company said.Pfizer also cited strong performance in its biopharma business due to good sales for cancer drug Ibrance, anticoagulant Eliquis and other medications.Pfizer said its Phase 3 Covid-19 trial had enrolled more than 40,000 participants, with nearly 36,000 having received their second vaccination as of Monday.Shares rose 0.7 percent to $38,20 in pre-market trading.