COVID-19 updates: White House press secretary Jen Psaki tests positive

Moderna announced Tuesday that it will make up to 110 million doses of its COVID-19 vaccine available to African nations at the company's "lowest tiered price."

The Massachusetts-based biotechnology firm said it is prepared to deliver the first 15 million doses by the end of this year, with 35 million doses in the first quarter of 2022 and up to 60 million doses in the second quarter.

"All doses are offered at Moderna’s lowest tiered price," the company said in a press release Tuesday.

Africa, the world's second-largest and second-most populous continent, remains the least-vaccinated region of the world against COVID-19, with just over 5% of its 1.3 billion people fully inoculated.

Moderna CEO Stephane Bancel said the new agreement with the African Union, a continental bloc consisting of the 55 member states that make up the countries of Africa, was facilitated in part by the White House. The deal is separate from the company's agreement with the global vaccine-sharing initiative COVAX to supply up to 500 million doses from late this year through 2022, according to the press release.

"This is the first step in our long-term partnership with the African Union," Bancel said in a statement Tuesday. "We believe our vaccine can play an important role in addressing the needs of low-income countries given its combination of high Phase 3 efficacy against COVID-19, strong durability in the real-world evidence, and superior storage and handling conditions. We recognize that access to COVID-19 vaccines continues to be a challenge in many parts of the world and we remain committed to helping to protect as many people as possible around the globe."

Moderna is also working on plans to allow it to fill doses of its COVID-19 vaccine in Africa as early as 2023, in parallel to building an mRNA vaccine manufacturing facility on the continent with the goal of producing up to 500 million doses each year, according to the press release.

Two South Florida school districts may be changing their polices on mask mandates in schools as COVID-19 cases decline.

A Broward County Public Schools spokesperson told ABC affiliate WPLG that an item could be added at a school board meeting Tuesday "regarding district’s COVID-19 protocols including the use of face coverings.”

The district had said it would revisit the mask mandate when the COVID-19 positivity rate reached 3% or lower for 10 consecutive days. Broward County has reached that threshold, the county's health department data shows.

Miami-Dade County Schools Superintendent Alberto Carvalho also indicated there may be a change to its mask mandate policy.

The school board is looking at several metrics including hospital admissions, community transmission and daily student cases. Carvalho said Friday would be a benchmark day.

Carvalho said last week that a new plan could entail "a mandatory mask policy but with an unrestricted, unrestricted, parent opt-out provision."

The European Medicines Agency on Monday approved the Moderna booster (which is a half dose of the initial booster) for people 18 and older.

The booster "given 6 to 8 months after the second dose led to a rise in antibody levels in adults whose antibody levels were waning," the EMA said.  

-ABC News' Christine Theodorou

The federal government on Monday released more details about how foreign tourists and other non-citizen, non-immigrant people flying to the U.S. can comply with recently-announced rules requiring them to be fully vaccinated.

These rules go into effect on Nov. 8.

People will be able to submit proof of vaccination to airlines electronically or via paper, an official said.

All vaccinated people -- Americans and non-Americans -- need to show proof of a negative test taken within three days before departure.

For unvaccinated people -- both Americans and non-Americans -- you need to show proof of a negative test within one day before. Children ages 2 to 17 must take a test but those under 2 don’t need to test.

Vaccine exemptions include: children under 18; some medical exemptions; and people traveling on non-tourist visas from countries with low availability of vaccines (signified by a country having a vaccination rate less than 10%). The U.S. will follow a list maintained by the WHO and these people will need have a “specific, compelling reason” for coming to the U.S., a senior administration official said.

The exemptions will represent a “very, very small number” of travelers to the U.S., a senior administration official said.

-ABC News' Ben Gittleson