The world has met news of a successful COVID-19 vaccine candidate with guarded optimism, but a number of challenges remain in producing, storing and distributing the treatment – and that’s assuming the vaccine and others in development are successful in preventing COVID.

Pharmaceutical company Pfizer announced Monday that there’s a vaccine efficacy rate above 90 percent, one week after the required second dose, for its mRNA vaccine developed in partnership with BioNTech. The efficacy results are based on a small sample size, though, and reported by Pfizer rather than in a peer-reviewed journal.

That said, it appears to be one of several vaccines, including a Moderna product, with the potential to turn the tide even as another wave of COVID infections arrives in many countries.

“We are reaching this critical milestone in our vaccine development program at a time when the world needs it most with infection rates setting new records, hospitals nearing over-capacity and economies struggling to reopen,” said Pfizer CEO Dr. Albert Bourla. “With today’s news, we are a significant step closer to providing people around the world with a much-needed breakthrough to help bring an end to this global health crisis.”

One of the biggest problems, and one with the potential to affect Africans in developing countries, is the extreme cold temperature at which the Pfizer vaccine must be kept. Even the glass vials may need to be modified to survive minus 70 Celsius storage requirements, which present enormous logistical questions for the developing world when access to even standard refrigeration is never a given, and transportation infrastructure and terrain are critical access and distribution challenges.

There are more than 1.8 million confirmed COVID cases on the continent, according to the latest World Health Organization numbers. At least 45,000 people have died.