What's the best way to get the best immunity from double-dose Covid-19 vaccine? Three weeks? Twelve weeks? Eight weeks? Scientists aren't sure.
With vaccine manufacturers saying that Covid-19 vaccine effectiveness is wearing off much more quickly than desired, there is a search to figure out how to improve results.
Medical experts have been left on the one hand defending the vaccine program as it stands, stating that the vaccines may not always be very effective in preventing Covid-19 infection, but insisting the medicine is doing a good job of preventing the most serious Covid-19 infections; and on the other hand, actively searching for how to improve upon what is a massive, global medical experiment.
Still, authorities say the vaccination program is limited in its value if it cannot prevent infections and keep them from spreading to others.
The United Kingdom is on its third recommendation for how much spacing there should be between the first and second dose of the Pfizer RNA vaccine, adjusting the advice as more information is learned. Now, some British experts say an eight-week interval between doses is the right amount. Pfizer recommended three weeks. The UK also tried twelve-weeks.
A new British study also finds a longer gap than originally recommended between doses of Pfizer's jabs provides better overall antibody levels and protection.
However, the study finds, the patient is not well protected after the first dose, prior to the second one.
Following two vaccine doses, neutralising antibody levels were twice as high after the longer dosing interval compared with the shorter dosing interval...[but] For the longer dosing interval ... neutralising antibody levels against the Delta variant were poorly induced after a single dose, and not maintained during the interval before the second dose."Study authors
Virologists say antibodies are just a piece of the immunity puzzle.
Scientists say the millions who have been naturally infected with Covid-19, either with or without symptoms, appear to have long-lasting and strong immunity to a repeat infection, including by variants.
Virologists say those who fight off Covid-19 naturally will generally not develop measurable antibodies, or-- if they do-- the antibodies will not remain present in the blood for measurement. Therefore, the presence of antibodies is not the determiner as to whether someone has immunity to Covid-19.