Photographer: Gabriela Bhaskar / Bloomberg
Photographer: Gabriela Bhaskar / Bloomberg
US public health advisers are evaluating recommendations for extending the interval between the first and second doses of Covid-19 vaccines, a potential strategy to obtain protection quickly for more people amid the spread of new variants.
A working group of the Advisory Committee on Immunization Practices at the Center for Disease Control and Prevention debated the idea, according to a person familiar with the discussions. It has not yet been decided whether the entire committee will address the issue and provide official guidance, the person said. Jose Romero, chairman of the committee and secretary of health for Arkansas, declined to comment because the deliberations are confidential.
US health officials have rejected a dose extension policy adopted by the UK that allows until 12 weeks between doses of Covid. Most pharmacists agreed, saying that policies should follow the protocols used in testing the injections, in which the intervals were set at three or four weeks. As dangerous variants threaten to increase cases in the U.S. in the coming weeks, however, some states are wondering what they can do to expand protection.
“We know that until we have enough vaccine, there needs to be some kind of prioritization scheme, ”Clay Marsh, czar of Covid-19 West Virginia, said in an interview. “The next question is: is it better to put a single dose in the arms of more people?”
Possible Strategy
President Joe Biden increased orders for vaccines for Moderna Inc. and the partnership of Pfizer Inc. and BioNTech SE, predicting that supplies will be available to vaccinate 300 million Americans by the end of the summer. The strain may decrease further in the coming weeks if a single injection vaccine of Johnson & Johnson is authorized, but immediate delivery should not be large.
States are still trying to speed up immunizations, and West Virginia is among those pushing for the CDC and the Food and Drug Administration to provide further guidance on dose extension, according to the person familiar with the discussions. A possible strategy involves adhering to the existing schedules for high-risk groups, such as health workers and the elderly, allowing flexibility in younger people with less exposure to the virus.
Read more: Why delaying Covid’s second vaccination is a mess: QuickTake
The debate over the pause between doses – three weeks between doses of Pfizer in company studies and four weeks between doses of Moderna – has been heated. Proponents of longer intervals say that a dose provides at least some protection, while detractors say it is unclear how long that protection lasts or even how much is provided.
A notable exception is AstraZeneca Plc, whose injection in Covid-19 was released in the United Kingdom and dozens of other countries, although not in the USA. Cambridge, UK-based Astra says its studies indicate that a 12-week interval increases effectiveness, and the World Health Organization recommended 8 to 12 weeks between doses in allowing the injection last week.
Both the CDC and the FDA have moderated their position on the matter. Shortly after Biden took office, the agencies said they would wait until six weeks between shots is acceptable in special circumstances.
Finding a balance
In Illinois, the demands of giving people second doses are overwhelming the state’s ability to administer the first doses. The number of Second doses in the state are likely to exceed first doses by March, when funds increase, the Department of Public Health said in a statement on Saturday.
“We have reached this balance between promoting the first doses and also the second doses”, Director Ngozi Ezike said on February 2 at a hearing in the US House of Representatives. “And we want to use the maximum doses available as quickly and effectively as possible.”
Photographer: Al Drago / Bloomberg
Anthony Fauci, Biden’s chief medical consultant, said last month that he is concerned about attempts to postpone the second injection.
“I would be concerned, because you don’t get full effectiveness until you get the second dose,” he said on January 25 at World Economic Forum.
‘Push the envelope’
There is also the potential that lower levels of protection afforded by one dose of vaccine compared to two may allow faster spreading variants to gain a higher position, said Jesse Goodman, a former FDA chief scientist, in an interview . A two-dose regimen with reduced efficacy against a mutant may be ineffective against the same strain in a single dose, said Goodman.
A longer interval with a single dose on board means “extending the period during which people are most at risk of being infected,” he said. “I personally saw and heard of several people who already catch Covid after the first dose.”
West Virginia will not make any move without the consent of federal officials, according to Marsh, the Covid czar, but he is looking at countries like the United Kingdom and Israel, where leaders are administering as many doses as possible.
“Our strategy for Covid needs to constantly balance what our national experts say,” he said, “but it is also our responsibility to our citizens to ensure that we are constantly trying to push the envelope.”