The first monitoring results of the vaccination campaign confirmed an efficacy of the Covid vaccines equal to about 90%. In almost all cases, therefore, those who had received a vaccine with messenger RNA he had developed antibodies capable of protecting him from the virus (or from more serious infections).
Less than a year after the start of the vaccination campaign, however, things have changed.
Covid vaccine: what antibody studies say
New studies have shed light on a possible decreased effectiveness of Pfizer vaccines after six months, starting from a comparison of the results with those of the patients who received Moderna. After some time – data and research in hand – it seems that today it is possible to confirm an effective decrease in antibody levels with Pfizer’s vaccine, particularly in older and more fragile people. Unlike Moderna which – over time – seems to generate more antibodies.
That the vaccine’s effectiveness does not depend solely on the level of antibodies has been debated. According to several scientists, in fact, the cd plays an important role in the fight against Covid. “Immune memory”, able to recognize the virus and fight it. Measuring the importance of antibodies in this case, however, represents a critical step: researchers are still working to understand on what the efficacy and protection of a vaccine depends and how this differs from one person to another. Getting these questions answered is crucial, as it helps identify who may need the booster and when to administer a possible third dose.
For this reason, many studies have focused on the analysis of antibodies produced and how they are able to block the invading pathogen, label it and allow the immune system to attack.
Pfizer vaccine, how efficacy declines over time
A recent US study, for example, looked at a group of patients (guests and nursing home staff) who received two doses of Pfizer vaccine. What emerged is that i levels of antibodies in both groups they decreased over time. Specifically, of the people observed, those with an average age of 76 years (120 patients residing in the facility) recorded a much lower level of antibodies than the younger staff. Over the months, the number of antibodies still dropped (increasingly drastically) among older adults, while two weeks after the second dose, neutralizing antibodies had fallen below the detection level in about 16% of home residents. care that they had not had Covid before the vaccinations. Six months after vaccination, 70% of these had extremely low levels.
Furthermore, that the efficacy of the vaccine may depend on the age and physical and health condition of people, it could also be confirmed by the data of the US study which reports a decrease in the level of antibodies only in 16% of the youngest health care workers involved (64 in total), six months after inoculation.
Pfizer and Modern to clash
On the different efficacy over time of the Covid messenger RNA vaccinesAlso recently, a second study from the University of Virginia was published which, in fact, confirmed the findings of the research that involved 1,600 health workers in Belgium (here the results of the observation). What the researchers have shown, in focus, is that the people who received the Modern vaccine they produced, on average, twice the levels of antibodies than those who received the Pfizer vaccine. The Belgian study, published in the Journal of the American Medical Association, also found that Moderna produces higher antibody levels in all age groups.
Comparing the data of 167 members of the medical staff employed at the University of Virginia, immunized with the Moderna or Pfizer vaccine, it was found that the levels of antibodies after the second vaccine were about the 50% higher in people who had received the Moderna vaccine.
It must be said, however, that no scientist until now has been able to understand if a lower number of antibodies translates – concretely – into less protection over time. Beyond the level of antibodies, the protection against severe forms of Covid and hospitalization – which is the goal of the large-scale vaccination campaign – remains generally strong in any case. It is a fact that, to date, hospitals continue to fill up with unvaccinated people, the same ones that continue to constitute the largest number of new serious cases.