The deputy director-general of the Health Ministry, Prof. Itamar Grotto, proposed on Sunday that the interval between the two doses of the COVID vaccine be increased from 21 days so that more people can be vaccinated sooner and receive at least some level of protection.
Although Pfizer's experimental proctol is for two vaccine doses to be given 21 days apart, documents published by the U.S. Food and Drug Administration (FDA) in early December indicate that the Pfizer vaccine provides "strong protection" against COVID-19 after the first dose.
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With infection rates on the rise, health officials wondered whether it would be preferable for more people to get vaccinated with the first dose, so as to double the number of people who will enjoy at least some protection against the virus. This deviation from Pfizer's experimental protocol is technically and regulatorily possible.
What Grotto suggested was the postponement of the second dose, not doing away with it altogether.
In a short statement published last Thursday entitled “Optimising the COVID-19 vaccination programme for maximum short-term impact,” the Joint Committee on Vaccination and Immunization (JCVI), which advises U.K. health departments, advocated the practice as a means of “maximizing protection in the population.”
They wrote: “Given the high level of protection afforded by the first dose, models suggest that initially vaccinating a greater number of people with a single dose will prevent more deaths and hospitalisations than vaccinating a smaller number of people with two doses. The second dose is still important to provide longer lasting protection and is expected to be as or more effective when delivered at an interval of 12 weeks from the first dose.”
They also wrote that “When considering vaccination schedules, JCVI often considers first principles, and regularly advises schedules which differ from the marketing authorisation. In every case, the advice of JCVI is aimed at maximising protection in the population.”
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On Thursday, Bloomberg reported that Pfizer insisted that the original protocol should be adhered to, adding that "there is no data to demonstrate that protection after the first dose is sustained" after 21 days.
According to the World Health Organization, an effective vaccine is defined as one having an efficacy rate of 50 percent or more. The vaccines produced by Pfizer, Moderna and Astra-Zeneca showed efficacy rates much higher than 50 percent.
“Published efficacy between dose 1 and 2 of the Pfizer vaccine was 52.4 percent," with most vaccine failures in the period between doses occurring shortly after vaccination, the JCVI wrote in their statement.
They also noted that “Using data for those cases observed between day 15 and 21, efficacy against symptomatic COVID-19 was estimated at 89 percent .. suggesting that short term protection from dose 1 is very high from day 14 after vaccination.”
They added that similar findings were found with respect to the Moderna vaccine, “up to 108 days after the first dose."
The Health Ministry has not adopted, and experts have not broadly backed, the proposal to deviate from the companies' formal approval protocol in line with the British plan. However, to the extent that the rate of supply of the vaccine does not keep up with demand, the Health Ministry will be required to seriously consider re-examining its immunization policy and to more fully engage with the question of which plan will maximize protection of the population.
The director-general of the Health Ministry, Prof. Hezi Levy, responded to Grotto’s proposal in a radio interview on Sunday morning. Prof. Levy repudiated the idea floated by his subordinate, reiterating the ministry’s commitment to administering two doses in accordance with the pharmaceutical company’s instructions, “the clinical trials that were conducted and the regulatory approvals that exist.”
He did however open up the possibility that this current policy would be revisited if another trend arises in the global scientific discourse, supported by the evidence.
Levy also expressed grave concern regarding the death toll and the number of patients in serious condition, warning that the “current lockdown will not reduce the infection rate” and emphasized that restrictions need to be tightened.
Although not backed Levy, the idea of postponing the second vaccine dose date is also supported by Prof. Eyal Leshem, an expert in internal medicine and infectious diseases and Director of the Center for Travel Medicine and Tropical Diseases at Sheba Medical Center in Tel Hashomer.
Leshem told Haaretz that postponing the second dose, also known as the booster dose, does not impair a vaccine’s efficacy “and sometimes even improves it.” He noted that “Israel and other countries give vaccines at a delayed date or in a smaller number than recommended if there is no significant efficacy reduction and there are financial savings or an improvement in the level of coverage."
Leshem suggested it would “be reasonable” to ensure full coverage of two vaccine doses for those at-risk, and one vaccine dose for those in lower-risk groups, such as those between the ages of 40 and 50 without background diseases.”