Pfizer expects revenue from the COVID-19 vaccine, co-developed by BioNTech, will reach $33.5 billion this year — a 29% jump from the previously estimated $26 billion.

Why it matters: This vaccine, which has dramatically slowed the coronavirus pandemic, is on pace to be the world's top-selling drug of all time, by far. And now Pfizer is pushing for people to get a third "booster" shot of its vaccine to combat the growing Delta variant.

By the numbers: Pfizer registered $7.8 billion of COVID-19 vaccine sales in the second quarter, bringing total worldwide sales so far this year to $11.3 billion.

• Pfizer expects to deliver 2.1 billion doses this year and has the capacity to manufacture 4 billion doses next year, CEO Albert Bourla said on a conference call.
• The U.S. previously paid $19.50 per dose for the Pfizer-BioNTech vaccine, but Pfizer recently raised the price to the government to $24 per dose.
• Flashback: Last year, Bourla said the company would not put a "huge price" on the vaccine, "because that's really taking advantage of a situation, and people will not forget if you do that."

Driving the news: Pfizer said it has new data showing a third dose of its vaccine increases antibody levels significantly against the Delta variant.

• Pfizer has a financial interest in people, especially Americans, getting a third dose, as it would grow revenues even more.
• However, epidemiologists have pointed out that higher antibody levels do not mean higher protection, and Pfizer's two-dose schedule is already effective against the coronavirus, including the Delta variant.

The big picture: A majority of the Pfizer-BioNTech vaccine has gone to wealthy countries, whose governments pay higher prices for drugs than lower-income countries.

• Many lower-income countries have started demanding more doses as their coronavirus cases, hospitalizations and deaths rise.
• "Africa was largely spared by the pandemic in 2020, but not this year. We lack vaccines, and we are gasping for air," Mosoka Fallah, former director-general of the National Public Health Institute of Liberia, said this week.

What to watch: Moderna reports vaccine sales and earnings Aug. 5.

• Johnson & Johnson said it expects its COVID-19 vaccine will generate $2.5 billion of sales this year.