Bad news is piling up for pharmaceutical giant Pfizer. According to a clinical study published by the scientific journal Jama, the immunity provided by the Pfizer vaccine against the Omicron variant would be short-lived.
The fragile immunity provided by the Pfizer/BioNTech vaccine confirmed by a scientific study
The immunity provided by the vaccine is far from being as robust as had been announced, as shown by a clinical study published on May 13, 2022 by the American scientific journal Jama Network. If the vaccine provides a small efficacy for a few weeks, this is greatly reduced after three months after the second dose and after ten weeks after the third, a data corroborated by the rapid decline in neutralizing antibodies specific to Omicron.
The study cohort included 128 vaccinated people who received either two doses (73 people) or three doses (51 people) of vaccine. Those vaccinated with a double dose had a median age of 51, while those who received three doses had a median age of 70. Among those vaccinated, there was also a small category of seven people vaccinated after being infected.
Four weeks after the second dose of the Pfizer/BioNTech vaccine, the results of the study show that the geometric mean titer (GMT) of antibodies against the Omicron variant is 14 times lower than the GMTs against the Wuhan wild-type strain (D614G) (Chart 1A). Going into the detail of this study, it can be seen that the proportion of detectable responses of neutralizing antibodies specific to the Omicron variant decreases rapidly, from 76.2% (16 out of 21 people) at the fourth week to drop to 53, 3% (16 people out of 30) between the eighth and tenth week and 18.9% (3 people out of 16) between weeks 12 and 14 compared to the primary strain, but also compared to the Delta variant (graph 1 HAS).
After the third dose of Pfizer/BioNTech vaccine, TGMs against the Omicron variant increased 20.6-fold at week three and 7.7-fold at week four, a result well above the TGMs that appeared following the second dose. This third dose elicited detectable neutralizing antibody responses in the majority of individuals for at least eight weeks; however, between week three and week eight, neutralizing antibody TGMs decreased 4.9-fold for primary strain D614G, 5.6-fold for Delta, and 5.4-fold for Omicron (Chart 1A) .
When the TGMs of Omicron-specific neutralizing antibodies were analyzed according to age, it was found that the immune response differed significantly between those aged less than 65 years and those aged over 65 after the second dose. This phenomenon is not observed after the third dose, since the difference between the two groups is much less marked (graph 1B). However, for the 5 individuals over the age of 65 studied at week 8 after dose 3, Omicron-specific TGMs were undetectable in 2 individuals and low in 3 individuals (Chart 2 D).
As with a third dose of vaccine after the first two-dose series, vaccination after prior infection significantly increased Omicron-specific TGMs (Graph 1C).
In addition, a very significant drop in neutralizing antibodies is observed in the eighth week for people aged over 65 following the third dose (graph 2 D).
Given these findings, far from discouraging vaccination, the study authors conclude that overall, vaccine-induced protective antibody responses following a second and third dose of Pfizer vaccine / BioNTech are transient. Therefore, additional booster doses may be needed, especially in the elderly. Further, they point out that T-cell retained immunity and non-neutralizing (neutral) antibodies may still provide protection against hospitalization and death.
Conclusions which led them to recommend a fourth dose of vaccine, now called a second booster dose.
Other figures confirm the loss of efficiency
This drop in vaccine effectiveness after a few weeks was also recorded in the clinical report of the Pfizer laboratory on the third dose filed with the Food and Drug Administration (FDA). An efficiency that would be between 39% and 65% for the Delta variant. A problematic figure when no authorization, even conditional, can be issued if it has not been proven that the vaccine has an effectiveness greater than 50%.
For its part, the Walgreens Company, an American company that operates the second largest pharmacy chain in the United States, provides even worse figures. Indeed, when we examine the table which offers an evaluation of people tested between May 6, 2022 and May 12, 2022, we see that the unvaccinated are less likely to contract Sars-CoV-2 and to develop an infection. than people who have received two or three doses of vaccine.
The new epidemiological data show a weak protection of vaccinated people and a failure in the transmission of the virus from one person to another. The potential effectiveness announced by the laboratories and which emanated from the first clinical trials, is not the actual effectiveness. Shouldn’t the new information provided in terms of usefulness, efficacy and harmlessness be elements to be taken into consideration in reorienting public policies?