A lot of new information has dropped recently about the efficacy of First Doses First.
First, as I mentioned yesterday, we now have epidemiologists and vaccine researchers saying that for people previously infected with COVID a second dose is not necessary and may be “overkill.” Given how many people have had COVID, this increases the net benefit to First Doses First for everyone significantly.
Second, an important new study verifies that for the AZ vaccine a longer delay for the second dose is better because it generates a more powerful immune response (picture from the FT). This is a common finding for vaccines. The authors write:
ChAdOx1 nCoV-19 vaccination programmes aimed at vaccinating a large proportion of the population with a single dose, with a second dose given after a 3 month period is an effective strategy for reducing disease, and may be the optimal for rollout of a pandemic vaccine when supplies are limited in the short term.
In addition “Analyses of PCR positive swabs in UK population suggests vaccine may have substantial effect on transmission of the virus with 67% reduction in positive swabs among those vaccinated.” In other words, the vaccine cuts transmission risk.
As I have said before “the US failure to authorize the AstraZeneca vaccine in the midst of a pandemic when thousands are dying daily and a factory in Baltimore is warmed up and ready to run is a tragedy and dereliction of duty of epic proportions.”
Third, the New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG), a scientific advisory group to the British government, recently considered the risks of immune escape from the delayed second dose strategy and concluded that although the risk is real it is likely small, especially in comparison to other sources of immune escape such as therapeutics and natural infection. Moreover, the risk is outweighed by the measurable benefits of getting more does out quickly.
It is not currently possible to quantify the probability of emergence of vaccine resistance as a result of the delayed second dose, but it is likely to be small.The UK currently has more than 1,000 COVID-19 related deaths each day and has limited supplies of vaccine. In the current UK circumstances the unquantifiable but likely small probability of the delayed second dose generating a vaccine escape mutant must be weighed against the measurable benefits of doubling the speed with which the most vulnerable can be given vaccine-induced protection.
..a single dose of vaccine does not generate a new/novel risk. Given what we have observed recently with the variants B.1.1.7 and B1.351, it is a realistic possibility that over time immune escape variants will emerge, most likely driven by increasing population immunity following natural infection.
The 4 UK Chief Medical Officers agree with the JCVI that at this stage of the pandemic prioritising the first doses of vaccine for as many people as possible on the priority list will protect the greatest number of at risk people overall in the shortest possible time and will have the greatest impact on reducing mortality, severe disease and hospitalisations and in protecting the NHS and equivalent health services.
Fifth, the US public health experts are beginning to come around to the economic point of view. Consider Experts tout delaying 2nd COVID vaccine dose as US deaths mount which notes:
“The maximum public health benefit would come from giving a single dose to as many people as possible, and following up with a second dose when supply improves,” said Neal Halsey, MD, of Johns Hopkins University, in an interview. Halsey and Stanley Plotkin, MD, co-authored a letter in Clinical Infectious Diseases last week explaining how delaying a second dose of vaccine would accelerate the US vaccine rollout.
Halsey said data from both companies show the first dose of the vaccine offers significant protection against COVID-19 in the short term, for at least 1 to 3 months after injection. He also said he and Plotkin believe this was the most beneficial public health strategy even before the arrival of new variants of the virus was discovered.
“There are a number of examples of changing [vaccination] course because ACIP takes into account public health impact,” Halsey said. “We asked the ACIP to review in depth this strategy to give one dose as rapidly as possible. Such a meeting should be scheduled as soon as possible.”
The University of Minnesota’s Michael Osterholm, PhD, MPH, said yesterday on “Meet the Press” that he believes the United States has to change direction on vaccine strategy in light of the possibility of a surge of new infections coming from variant strains.
I believe that the US will go to First Doses First. The only question is will we go to First Doses First soon, when it can still help, or will we be forced to do it later in an act of desperation and agony.