US, UK Officials Seek to Stretch Vaccine Doses

Ralph Ellis

January 04, 2021

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

With COVID-19 case counts rising daily, health authorities in the United States and the United Kingdom are looking for ways to get more people vaccinated with a limited supply of vaccine.

The US government is considering cutting doses of the two-shot Moderna coronavirus vaccine in half in an attempt to potentially double the number of vaccinations, Moncef Slaoui, PhD, the scientific head of Operation Warp Speed, said Sunday on CBS's Face the Nation.

Slaoui said research shows that two 50-microgram doses of the Moderna vaccine have the same result in people 18-55 years old as two 100-microgram doses.

He said giving the smaller doses "means exactly achieving the objective of immunizing double the number of people with the doses we have. We know it induces identical immune response to the 100-microgram dose, and therefore we are in discussion with Moderna and with the FDA."

The FDA would have to approve such a decision, he said.

The New York Times reported that Moderna spokesman Ray Jordan did not comment on Slaoui's idea. But he said Moderna's clinical trials used two doses of 100 micrograms, 4 weeks apart.

Federal officials in the United States have said the vaccine is not being rolled out as quickly as they'd hoped. More than 13 million doses of the Moderna and the Pfizer vaccines have been distributed, but only 4.2 million had been given as of Saturday morning, according to the CDC.

Meanwhile, the UK is struggling with its own vaccine rollout. Cases are surging, partly because of a COVID variant in the UK, and much of the nation is in lockdown. The UK was the first nation to approve the Pfizer vaccine.

As a remedy, the chief medical officers of the UK government say the second Pfizer shot should be delayed in an attempt to give the first shot to as many people as possible.

"The second vaccine dose is likely to be very important for duration of protection, and at an appropriate dose interval may further increase vaccine efficacy," the chief medical officers for Wales, Northern Ireland, Scotland, and England said in a letter to the public.

"In the short term, the additional increase of vaccine efficacy from the second dose is likely to be modest; the great majority of the initial protection from clinical disease is after the first dose of vaccine."

Under this recommendation, the two shots would be given 12 weeks apart, rather than 2 to 3 weeks apart. The health ministers' letter called the idea "a classic public health approach centered on doing as much good for as many people in the shortest possible timeframe...."

But Pfizer says it has no data to back the UK plan.

"Pfizer and BioNTech's phase III study for the COVID-19 vaccine was designed to evaluate the vaccine's safety and efficacy following a 2-dose schedule, separated by 21 days," Pfizer said in a statement. "There are no data to demonstrate that protection after the first dose is sustained after 21 days."

A group of British doctors said the delay in giving second doses could endanger elderly people.

"This group of very elderly patients is at the highest risk of death if they contract COVID-19, which is why GPs are so concerned for them. It is grossly and patently unfair to tens of thousands of our most at-risk patients to now try to reschedule their appointments," Richard Vautrey, chair of the British Medical Association General Practitioners Committee, said in a statement, according to CNN.

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