Read the following passage and choose the correct answer to each of the following questions.

In an unexpected sign of hope amid the expanding pandemic, scientists at the University of Oxford said on Tuesday that an inexpensive and commonly available drug reduced deaths in patients critically ill with COVID-19.

If the finding is officially confirmed, the drug, a steroid called dexamethasone would be the first treatment shown to reduce mortality in severely ill patients. Had doctors been using the drug to treat the sickest Covid-19 patients in Britain from the beginning of the pandemic, up to 5,000 deaths could have been prevented, the researchers estimated. In the study, it reduced deaths of patients on ventilators by one-third, and deaths of patients on oxygen by one-fifth.

Until now, hospitals worldwide have had nothing to offer these desperate, dying patients, and the prospect of a lifesaving treatment close at hand - in almost every pharmacy - was met with something like elation by doctors.

Dexamethasone is the first drug to be shown to improve survival in Covid-19, one of the trial's chief investigators, Peter Horby, a professor of emerging infectious diseases at the University of Oxford, said in a statement. The survival benefit is clear and large in those patients who are sick enough to require oxygen treatment.

However, there is still, obviously, a significant amount of scepticism. While hospitals in the United Kingdom were allowed to begin treating severely ill COVID-19 patients with dexamethasone, many experts in the United States demanded to see the data and the study itself, which have not yet been peer reviewed or published.

(Adapted from nytimes.com)

According to paragraph 2, it is estimated by researchers that _____