The U.S. government announced on Wednesday a whopping $1.95 billion contract with vaccine candidates Pfizer and BioNTech SE. The investment would go towards securing 100 million doses of their vaccine to be provided to Americans for free.

Under the agreement, the United States will receive 100 million doses after regulators clear it. The Department of Health and Human Services may also acquire an additional 500 million doses if needed.

During a press conference at the White House on Wednesday, President Donald Trump touted both companies who are jointly developing four potential coronavirus vaccines. If the vaccine is proven safe and effective, Pfizer, with guidance from the U.S. government, will begin delivering doses to multiple locations across the nation, CNBC reports.

How effective is the vaccine developed by Pfizer and BioNTech?

While dozens of vaccines are currently being studied, not one has been proven to work safely yet. But data released by Pfizer Inc. and BioNTech SE in early July showed very promising results.

Healthy volunteers who received the first dose of the vaccine candidate had higher levels of antibodies after a month. They also had more antibody levels seven days after getting a second dose compared to the levels found in recovered COVID-19 patients. The researchers did not observe any severe side effects, The Wall Street Journal reports.

The Pfizer-BioNTech vaccine candidate uses messenger RNA (mRNA). The innovative gene-based technology is responsible for carrying instructions from DNA to the body's cells to make proteins.

The companies launched its first human study in May. The first phase focused on determining whether the vaccine candidates were safe.

Researchers enrolled 45 subjects who were between the ages of 18 and 55. Some were assigned with the vaccine candidate while others received a placebo. The team used three doses - 10 micrograms, 30 micrograms, and 100 micrograms.

After a month, the average antibody level for patients who received two dosages of 10 micrograms each had 4,813 units per microliter. The average antibody levels found in recovered patients was 602 units per microliter.

What are the other companies developing COVID vaccines?

Moderna had recently received funding from the U.S. government. The $483 million will go towards its vaccine development that also uses the mRNA technology. Phase III of its clinical trials is set to begin on July 27 and involve over 30,000 candidates.

AstraZeneca and the University of Oxford are now conducting the final phase of its vaccine candidate in Brazil and South Africa. The project aims to deliver two billion doses by October.

Europe is also pulling out all stops to develop a vaccine. Germany recently took a 23 percent stake in CureVac. It is the German firm President Trump once tried to lure. It launched the first phase of its trials in June.

Chinese researchers collaborated with the Academy of Military Medical Sciences to develop one of China's leading vaccine candidates. Chinese-firm Sinopharm Group announced in June that it would launch the last phase of trials in the UAE, as reported by The New York Times.

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