Even in non-pandemic times, the public health authorities of certain countries, notably Britain, have sometimes deviated from vaccine schedules tested in clinical trials without conducting additional trials.
Take the vaccine for seasonal influenza. The schedule endorsed by the American Academy of Pediatrics calls for two doses to be given four weeks apart to children between six months old and eight years old the first time they are inoculated. But the health authorities in Britain have decided — and without first formally testing this out in a trial — to forgo the booster dose for most two- to nine-year-olds, in order to get available vaccines out to more children.
Similarly with the pneumococcal conjugate vaccine. In the United States, it is administered in three injections during the first year of life followed by a booster at age one; this is the so-called 3+1 schedule. Many European countries have dropped one of the first three doses (that’s the 2+1 schedule) — and with no apparent reduction in protection. The World Health Organization has endorsed administering a total of just three shots (whether 2+1 or 3+0).
There is evidence today that something similar could be true with Covid-19 vaccines. In both the Pfizer-BioNTech and Moderna Phase 3 trials, the first dose achieved at least 89 percent efficacy starting two weeks after immunization. Preliminary data from Israel’s mass inoculation campaign suggest likewise, with significant protection against infection reported in the first 430,000 individuals who received an initial shot.
As the F.D.A. points out, estimates of efficacy rates after the first dose in clinical trials are based on a short period of observation: Most participants receive their second dose just three or four weeks later. In theory, delaying the second doses could mean that whatever immunity individuals acquired after the first shot would wane in the interim. Yet typically — as with the vaccines against meningococcus, influenza or typhoid — if immunity following a single dose wanes at all, it does so over months or years, not in a matter of weeks. Just one dose can buy a lot of time.
The Biden administration’s by-the-book approach to Covid-19 vaccination — two shots and delivered, as much as is possible, according to the schedule set by manufacturers — may be the safest for policymakers, but it isn’t the safest for the public. It’s overly prudent, and at this stage of the pandemic, the excess of caution is killing people.
More lives could be saved if we simply forgot about boosters and more trials for a while and rushed right now to give just one shot to all the people who are most immediately at risk of dying.
Adam Finn (@adamhfinn) is a senior clinician in the pediatric immunology and infectious diseases clinical service at Bristol Royal Hospital for Children and a professor of pediatrics at the University of Bristol. Richard Malley (@rickmalley) is a physician specializing in infectious diseases at Boston Children’s Hospital and a professor of pediatrics at Harvard Medical School.
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