ROME (AP) — American pharmaceutical company Pfizer and German company BioNTech have pledged to deliver 2 billion doses of their COVID-19 vaccine to middle- and low-income countries over the next 18 months. The companies made the announcement Friday at a global health summit in Rome co-hosted by the European Union’s executive arm and Italy. Pfizer CEO Albert Bourla said they expect to provide a billion of the doses this year and another billion in 2022. It was unclear whether the deliveries would take place through the U.N.-backed COVAX program, which aims to ensure equitable access to COVID-19 shots for low-and middle-income countries, or if countries would get the doses at a reduced price directly from the companies.