One of the world’s largest-ever one-day vaccination campaigns happened Saturday, March 10, across Puerto Rico.

Thanks to a daylong event conducted by the VOCES Puerto Rico Vaccination Coalition, Puerto Rico’s Department of Health, the CDC Foundation, Direct Relief and others, 9,426 people were vaccinated against influenza at 55 different locations across the island.

“A year-round flu season, combined with the damage inflicted by Hurricane Maria to Puerto Rico’s vaccine inventories, has left the island’s population severely vulnerable to influenza and other conditions,” said Lilliam Rodríguez, President and Founder of VOCES Puerto Rico. “Immediate action through immunization is needed to protect the lives and health of the population. Today’s island-wide vaccination campaign aims to close the immunization gap and promote health for all.”

Free influenza vaccinations were offered Saturday at the 18,500-person capacity Jose Miguel Agrelot Coliseum in San Juan and more than 50 vaccination centers, pharmacies, hospitals and primary health centers throughout the island.

Direct Relief provided 40,000 doses of influenza vaccine donated by pharmaceutical maker Sanofi S.A. for the initiative. Direct Relief is also providing logistics support and funding to rent the Coliseum and hire support staff for the event. With nearly 10,000 people already vaccinated as a result of Saturday’s event, the remaining vaccines can be used for additional immunizations.

“Hurricane Maria dealt a doubly cruel blow to Puerto Rico, devastating countless lives and livelihoods while damaging the health facilities, systems, and infrastructure needed to recover,” said Thomas Tighe, president and CEO, Direct Relief. “That’s why the work of VOCES and others to promote health and wellbeing across Puerto Rico are so critical. It’s a privilege for Direct Relief to support today’s mass immunization campaign and participate in these exceptional efforts to help people in Puerto Rico recover and live healthy lives.”

Puerto Rico’s healthcare system was devastated by Hurricane Maria last September, leaving fewer Puerto Ricans vaccinated this flu season. Dozens of clinics were shut and most lost the electrical power needed to refrigerate vaccines. Many clinics still don’t have electrical grid power.

“Sanofi Cares North America is proud to partner with Direct Relief in supporting this unprecedented flu vaccination campaign for the residents of Puerto Rico,” said Peter Lalli, President of Sanofi Cares North America. “We stand with the people of Puerto Rico as the recovery from the devastation of Hurricane Maria continues.”

Flu has been widespread in Puerto Rico this season. The Centers for Disease Control and Prevention on Friday reported that “34 states plus Puerto Rico continue to report widespread flu activity,” and while activity dropped from this year’s peak, it still matches the height of the 2015-16 season.

“We remain committed to making vaccines accessible to the Puerto Rican community, and to reach any region of the Island that needs it,” said Dr. Rafael Rodríguez Mercado, Secretary of Health, in a Spanish-language statement issued by VOCES.

In the six months since Hurricane Maria made landfall,  Direct Relief has supported 58 health facilities across Puerto Rico with $61.9 million in medications and medical supplies.

“Direct Relief was the first nongovernmental organization to provide vaccines to Puerto Rico after hurricane Maria,” said Dr. Rafael Rodriguez Mercado, Secretary of the Puerto Rico Department of Health. “Their efforts saved lives and prevented epidemic outbreaks, and we are exceedingly grateful to Direct Relief and other organizations for their continued support and partnership.”