Full COVID-19 vaccination could ultimately mean three doses

While mRNA vaccines from Moderna (NSDQ:MRNA) and Pfizer (NYSE:PFE) had 95% efficacy in Phase 3 clinical trials, their effectiveness in the real world has dropped with the rise of the Delta variant. 

As a result, breakthrough infections have grown more common in people who have received two doses of mRNA vaccines.

Ultimately, full vaccination may require three doses, concluded Chief Medical Advisor to the President Dr. Anthony Fauci in a press briefing. While acknowledging that the FDA would need to make the final decision, “I must say from my own experience as an immunologist, I would not at all be surprised that the adequate full regimen for vaccination will likely be three doses,” Fauci said. 

In the briefing, Fauci pointed to booster data emerging from Israel recently published in a preprint. The Pfizer-BioNTech vaccine led to a 70% to 84% risk reduction 14 days after administration of a third dose. 

A separate preprint found that a third dose led to an 11.4-fold reduction in risk of confirmed infection and severe disease from COVID-19. “Under a conservative sensitivity analysis, we find ≈5-fold protection against confirmed infection,” the report authors concluded.

Fauci hinted that such “very favorable” data supported a similar approach in the U.S. 

Fauci also said it was likely that the strong immune response from a third dose would be durable. If that proves to be accurate, “then you’re going to have very likely a three-dose regimen being [routine],” Fauci said. “But we’ll just have to wait to make sure that that’s the case when the data get presented to the FDA.”

Booster doses are already available in the U.S. for some immunocompromised individuals. Biden has also predicted that COVID-19 boosters would be available to the broader public in the near future.

Fauci acknowledged that the growing appetite for boosters in wealthy countries might complicate efforts to vaccinate the public in developing countries. “That’s the reason why the United States is setting an example” by donating hundreds of millions of doses to developing countries. 

The U.S. government has also worked with COVID-19 vaccine manufacturers to stimulate production. The U.S. recently pledged to purchase 500 million doses of the Pfizer-BioNTech vaccine for donation in the developing world. 

The U.S. also will provide $3 billion to bolster the supply chain for COVID-19 vaccines, announced ​​White House COVID-19 adviser Jeffrey Zients in the news conference. The funding will provide lipids, bioreactor bags, tubing, syringes, and personal protective equipment such as gloves, Zients said, without commenting on which companies would receive the funding, noting that the contracting process would begin in coming weeks. 

Zients noted that the funding would help the U.S. provide boosters and supply other nations. “We can protect the American people and contribute to the world as we are leading the world in vaccine doses donated,” he said. 

The U.S. has donated 130 million doses of COVID-19 vaccines to 90 countries thus far. “We’ll be giving 200 million before the end of the year and another 300 million by June of 2022,” Fauci said.